UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Causality in science Kampe, Cornelius 1966

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1966_A8 K34.pdf [ 2.39MB ]
Metadata
JSON: 831-1.0104684.json
JSON-LD: 831-1.0104684-ld.json
RDF/XML (Pretty): 831-1.0104684-rdf.xml
RDF/JSON: 831-1.0104684-rdf.json
Turtle: 831-1.0104684-turtle.txt
N-Triples: 831-1.0104684-rdf-ntriples.txt
Original Record: 831-1.0104684-source.json
Full Text
831-1.0104684-fulltext.txt
Citation
831-1.0104684.ris

Full Text

C A U S A L I T Y I N S C I E N C E by C o r n e l i u s Kampe B . S c , U n i v e r s i t y of B r i t i s h Columbia, 196k-A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR TH E DEGREE OF M.A. i n the Department of PHILOSOPHY We accept t h i s t h e s i s as conforming to the re q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1966 i i In p resen t i ng t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r re fe rence and s tudy . I f u r t h e r agree tha t p e r -m iss ion f o r e x t e n s i v e copy ing o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s understood that copy ing o r p u b l i -c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed w i thout my w r i t t e n p e r m i s s i o n . , Department o f PHILOSOPHY The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada Date A p r i l 1?, 1966. i ABSTRACT The concept of c a u s a l i t y understood as l a w - l i k e r e g u l a r i t y , pervades science from the a p p l i e d or p r a c t i c a l to the t h e o r e t i c a l s c i e n c e s , from i t s e a r l y days to the present. But, workers l i k e R u s s e l l and Hanson have c o r r e c t l y observed th a t e x p l i c i t mention of causes tends to disappear i n advanced and s t r i c t l y t h e o r e t i c a l sciences l i k e p h ysics and g r a v i t a t i o n a l astronomy. The concept of p r e d i c t i o n or e x p l a n a t i o n i n accordance w i t h general laws, r e p l a c e s the e a r l i e r , c a u s a l concepts. The l i m i t i n g form of t h i s process i s a science where Hempel-Oppenheim e x p l a n a t i o n i s achieved. Here the c o n t r o v e r s i a l symmetry between explanations and p r e d i c t i o n s , as i m p l i e d by Hempel 1s view, does e x i s t even i f i t does not i n a more p r i m i t i v e s c i e n t i f i c work. Only quantum mechanics casts doubts on t h i s t h e s i s , but co n t r a r y to views advanced by Hanson, the symmetry t h e s i s can be extended i n t o t h a t d i s c i p l i n e . i i i ACKNOWLEDGEMENT A f t e r r e c e i v i n g my Bachelor of Science degree, I went to see Pr o f e s s o r Barnett Savery, the head of the department of philosophy. I was very f o r t u n a t e to f i n d a r e a l philosopher whose guidance i n a genuine p h i l o s o p h i c a l s p i r i t gave me encouragement. In h i s department under the guidance of Dr. Ian Hacking, I have completed the work I present here, on the question of c a u s a l i t y i n sc i e n c e . I t was a pleasure f o r me to be introduced by Dr. Hacking i n t o independent p h i l o s o p h i c a l t h i n k i n g . i v TABLE OF CONTENTS I ON CAUSES IN PRACTICAL SCIENCE page 1 I I ' "WHY QUESTIONS" CORRESPOND TO CAUSES AND "HOW QUESTIONS" CORRESPOND TO LAW-LIKE EXPLANATIONS page 10 I I I CAUSES IN C. G. HEMPEL1S EXPLANATIONS page 16 IV - EXPLANATIONS AND PREDICTIONS IN QUANTUM MECHANICS page 20 CONCLUSION ' • page 33 NOTES page 3*+ BIBLIOGRAPHY page 36 .1 . ON CAUSES IN PRACTICAL SCIENCE In g i v i n g the cause f o r a p a r t i c u l a r occurrence both i n everyday a f f a i r s as. w e l l as i n p r a c t i c a l s c i e n c e , we are making a statement which may be put i n the form: 'whenever X then Y 1. The i n i t i a l c o n d i t i o n X has to be a s u f f i c i e n t c o n d i -t i o n f o r the occurrence of Y. One may d i s t i n g u i s h between two i n t e r p r e t a t i o n s ( i ) X determines Y i n the sense of having the power to b r i n g about Y. (John Locke spoke of the idea of cause as the idea of o p e r a t i o n w i t h something operating which we. c a l l a cause. )^~~^ ( i i ) X and Y are r e l a t e d i n the Humean sense of constant c o n j u n c t i o n . . In a Humean account, any t a l k about Y's occurrence i s incomplete f o r we must determine how X and Y r e l a t e ; how prece-dent occurrences r e l a t e w i t h consequent occurrences according to a law. This i s e x a c t l y what a more, advanced science does. On the other, hand causes 'having power' i s a p r e - c r i t i c a l manner of speaking f o r the 'power' i s a p o s t u l a t e d o c c u l t q u a l i t y . An i n q u i r y i n t o understanding the world which i s r e s t r i c t e d to causes^iri incomplete i n that the form or the func-t i o n a l r e l a t i o n s h i p between antecedent and consequent occurrences i s omited. I w i l l now t u r n to an i n v e s t i g a t i o n of causes i n p r a c t i c a l science to i l l u s t r a t e how causes are used and to i l l u m i n a t e t h i s incomplete or fragmentary d e s c r i p t i o n of nature. (2) In 1910, Bertrand R u s s e l l v ' sha r p l y c r i t i c i z e d the n o t i o n of c a u s a l i t y n o t i n g i n p a r t i c u l a r t h a t causes are excluded from advanced s c i e n c e . However, the word 'cause' continues to be used i n s p i t e of i t s omission from t h e o r e t i c a l , science. The medical doctor w i l l say, " D e p r i v a t i o n of "ascorbic a c i d causes..4 2 s c u r v y " ^ according to t h i s usage i t seems that the cause i s the l a c k of some e s s e n t i a l i n g r e d i e n t . The consequent c o n d i t i o n , of good or had h e a l t h i s r e l a t e d to a set of antecedent co n d i -t i o n s i n a r e l a t i o n s h i p of the type l (1) i f A, B and C then G (good h e a l t h ) (2) i f not A, or not B or not C, then not G (poor h e a l t h ) . U s u a l l y i n t a l k i n g about the cause of some ef f e c t , , we t a l k about the presence or occurrence of some event, or p o s s i b l y body which may act as an agent, i n the prod u c t i o n of the e f f e c t ; t h a t i s , we t a l k i n terms of type 1 above. However, i n p r a c t i c a l s c i e n c e , the no t i o n ' o f cause i s not r e s t r i c t e d to ( 1 ) . This seems to imply that the n o t i o n of agency i s not e s s e n t i a l to the concept of cause i n t h i s usage. I f someone s a i d that cause always i n v o l v e s agency, even i n the case of ' l a c k s ' , he might counter my c l a i m by saying t h a t , '"To say tha t l a c k of A causes B i s to say tha t there i s . an agent C tha t causes B but would not cause B i n the presence of A." I t i s c l e a r l y the case that 'cause' i s used i n sentences of the form 'lack of A causes B'. What i s i n que s t i o n i s : i f such an agent can be found, what i s the s t a t u s of the agent? Can we i d e n t i f y t h i s agent and observe i n an experimental s i t u - , a t i o n whether or not the agent operates i n the presence or absence of A? I f not, i s the agent merely a p o s t u l a t i o n having no inde-pendent grounds f o r i t s existence other than s a t i s f y i n g the need to have an agent always a c t i n g as the cause? The problem becomes e a s i e r by c o n s i d e r i n g the example, " D e p r i v a t i o n of a s c o r b i c a c i d causes scurvy". Modern medical knowledge does not r e v e a l the presence of an agent which causes 3 ; scurvy i n cases where a s c o r b i c a c i d i s l a c k i n g . Such an agent would have only p o s t u l a t i o n a l s t a t u s . Let us t r y to b u i l d as strong a case f o r the 'agency theory' as p o s s i b l e . On being t o l d t h a t t h e l a c k of n u t r i t i o u s food causes d i s e a s e s , the advocates of agent as cause would, p o i n t out t h a t ' i n the 'absence of n u t r i t i o u s food there are agents, b a c t e r i a , which cause i l l h e a l t h ' , ( i n f e c t i o u s b a c t e r i a a t t a c k the . weakened organism). B a c t e r i a can be i d e n t i f i e d more s p e c i f i c a l l y on independent grounds as causes of i l l n e s s e s . The presence or absence of p a r t i c u l a r b a c t e r i a i s r e l a t e d to the presence or absence of some p a r t i c u l a r i l l n e s s . In u s i n g language, we c a l l both ' b a c t e r i a ' and 'lack of n u t r i t i o u s food' causes, choosing one i n preference to the other depending on which i s more a c c e s s i b l e to m a n i p u l a t i o n i n a p a r t i c u l a r experimental s i t u a t i o n , or choosing one i n preference to the other depending on which l e v e l microscopic or macroscopic we wish to make our a n a l y s i s . To m a i n t a i n or even to understand the t h e s i s that 'cause must be an agent', i t i s important f o r us to n o t e , i n p a r t i -c u l a r the s t a t u s of an agent as cause. That i s , i l l h e a l t h can be given a number of causes among them, a cause which i s recognized as an agent.. There are no grounds f o r the statement t h a t only agents are causes where the causes of some event are spoken of as l a c k s , agents or s t a t e s . Turning to our previous example, ' b a c t e r i a , cause c a r i e s ' , we may ask, 'how do b a c t e r i a cause c a r i e s ? ' To ask f o r what purpose (why) b a c t e r i a cause c a r i e s i s simply t e l e o l o g i c a l . Such questions are excluded from s c i e n c e . A • complete answer to the 'how' q u e s t i o n w i l l i n v o l v e us i n the metabolism of b a c t e r i a and chemistry of b a c t e r i a l a c t i o n , and the chemistry of the body. No agent here. Then j u s t as 'cause 1 i n the sense of l a c k was found to be incomplete, so a l s o 'cause' as agent i s incomplete i n so f a r as f u r t h e r a n a l y s i s does not r e s t content w i t h bac.teria as agents. In o r d i n a r y d i s c o u r s e , we may ask "Why d i d Mr. X get up and leave the t a b l e before dinner was f i n i s h e d " . Two d i s t i n c t types of answers are o f t e n given. In terms of purpose, Mr. X's a c t i o n could be described as r e s u l t i n g from h i s d e s i r e to hear the news. Then h i s purpose i n l e a v i n g the t a b l e was to t u r n on the r a d i o . A l t e r n a t i v e l y , the same occurrence may be described i n terms of h a b i t and n e u r a l p r e f e r e n t i a l pathways. "Mr. X l e f t the t a b l e because the mantle c l o c k 'struck s i x ' . " The s t r i k i n g of the c l o c k i n i t i a t e d h i s response to go to the r a d i o and ' f l i c k ' on the s w i t c h which he has been doing f o r the past ten years. I n the one case, the a c t i o n r e s u l t e d from the motive to achieve a c e r t a i n end. The other answer i s c a u s a l : a p a r t i c u l a r e x t e r n a l stimulus caused Mr. X. to get up. G i l b e r t Ryle objects to motives being causes saying as f o l l o w s : " to e x p l a i n an a c t i o n as done from a c e r t a i n motive i s not to c o r r e l a t e i t w i t h an o c c u l t cause, but to subsume i t (h) under a p r o p e n s i t y or behaviour t r e n d . " v ' The o c c u l t cause to which Ryle r e f e r s i s the f a c u l t y of v o l i t i o n s which he vehemently r e j e c t s , proposing f o u r types of d i f f i c u l t i e s which v o l i t i o n i s t s have to surmount. He concludes: "Motives are not happenings and are, t h e r e f o r e , not of the r i g h t type to be c a u s e s . " w y The c a u s a l e x p l a n a t i o n (the one which e x p l i c i t l y mentions a cause), i l l u s t r a t e a p r i m i t i v e type of s c i e n t i f i c e x p l a n a t i o n . . 5 The event 'mantel c l o c k s t r i k i n g s i x ' i s r e l a t e d f o r t h i s p a r t i c u l a r man to the response ' f l i c k i n g the r a d i o switch' according to the r e l a t i o n s h i p whenever X then Y. A more complete e x p l a n a t i o n f o r t h i s p a r t i c u l a r occurrence as might he made by a p h y s i o l o g i s t would be i n terms 'of p r e f e r e n t i a l n e u r a l pathways r e l a t i n g stimulus to response without e x p l i c i t mention of cause. States are sa i d to be causes i n sentences of the f o l l o w i n g form: 'What caused him to give up the Church?' d i s i l l u s i o n w i t h the Pope's stand on c o n t r a c e p t i o n ' . To say that a man i s d i s i l l u s i o n e d i s to make a d i s p o s i t i o n a l s t a t e -ment about him i n the Rylean sense. "To possess a d i s p o s i -t i o n a l p r o p e r t y " , according to Ryl e , " i s not to be i n a p a r t i -c u l a r s t a t e , or to undergo a p a r t i c u l a r change; i t i s to be . bound or l i a b l e to be i n a p a r t i c u l a r s t a t e , or to undergo a p a r t i c u l a r change, when a p a r t i c u l a r c o n d i t i o n i s r e a l i z e d " . ^ \ I f A i s d i s i l l u s i o n e d ( d i s p o s i t i o n a l ) , then he i s bound or l i k e l y to do so and so i n such and such circumstances. This i s a l l t h a t i s meant by saying t h a t d i s i l l u s i o n or love are s t a t e s . According to G i l b e r t Ryle's a n a l y s i s , the general f a c t t h a t a person i s disposed to act i n such and such circum-stances does not by i t s e l f account f o r h i s doing a p a r t i c u l a r t h i n g at a p a r t i c u l a r moment, any more than the f a c t t h a t the gl a s s was b r i t t l e accounts f o r i t s f r a c t u r e at 10 p.m. as the impact of the stone at 10 p.m. caused the g l a s s to break. We do, however, use the word'state' i n other contexts than the p r e v i o u s l y considered d i s p o s i t i o n a l manner. In p h y s i c s , we t a l k about energy s t a t e s of atoms. "Bohr suggested t h a t , 6 inasmuch as Planck had already shown tha t the c l a s s i c a l theory d i d not adequately d e s c r i b e the i n t e r a c t i o n between r a d i a t i o n and matter, i t was reasonable to assume that there were c e r t a i n s t a t i o n a r y s t a t e s i n which an atom d i d not r a d i a t e at a l l . Each of these s t a t e s i s c h a r a c t e r i z e d by a d e f i n i t e energy. They are separated by f i n i t e energy. They are separated by f i n i t e energy d i f f e r e n c e s . Emission and a b s o r p t i o n of r a d i a t i o n take place when the atom makes a t r a n s i t i o n from one s t a t e to (7) another". In what sense can the higher energy s t a t e be s a i d to cause the emission of r a d i a t i o n ? By higher energy s t a t e we mean a ' s t a t e ' above the normal s t a t e of lowest energy. To t a l k about atomic s t a t e s i s to_ t a l k i n the hypo-t h e t i c a l language — i f . . . . . t h e n . The s t a t e of an atom cannot be i d e n t i f i e d apart from the a b s o r p t i o n or emission of photons. I f we are t r e a t i n g the emission or a b s o r p t i o n as e f f e c t s , then the cause cannot be i d e n t i f i e d on independent grounds. F u r t h e r -more, although an atom which i s s a i d to be i n a p a r t i c u l a r . e x c i t e d s t a t e ( i . e . the f i r s t e x c i t e d s t a t e above ground s t a t e ) , e v e n t u a l l y decays w i t h the emission of a photon w i t h a unique energy a s s o c i a t e d w i t h that t r a n s i t i o n , the time at which t h i s t r a n s i t i o n occurs i s indeterminate. Only the h a l f l i f e f o r some p a r t i c u l a r . s t a t e i s knowable. C l a s s i c a l l y , i f A i s i n a s t a t e S, then something i s s t i l l r e q u i r e d to i n i t i a t e an a c t i o n ; the s t a t e p r e d i c t s the type of response. I t does not i n i t i a t e the occurrence of the e f f e c t . To say, then, t h a t the s t a t e of an atom i s the cause of the emission of some p a r t i c u l a r photon i s to make two ser i o u s e r r o r s . F i r s t l y , i t i s to introduce an o c c u l t cause. , 7 Secondly, i t i s to say that the cause of some e f f e c t can con-t i n u e to e x i s t f o r some u n s p e c i f i e d time without producing the e f f e c t . I t i s to say something s i m i l a r to 'the cause of the breaking of the g l a s s was i t s b r i t t l e n e s s ' . There i s a f u r t h e r common use of 'cause' as s t a t e . We o f t e n say: 'the warm weather, (a s t a t e ) , caused the snow to m e l t . 1 This i s equi v a l e n t to saying, 'The snow melted because of the warm weather'. We o f t e n a l s o reverse the order and say, 'I know i t i s warm because' the snow i s m e l t i n g ' . The f a c t i s , . to say ' i t i s warm', i s to say the snow i s m e l t i n g , my hands are not f r e e z i n g , e t c . Warm and c o l d , of course, are words whose meaning v a r i e s according to context. In summer, 65 degree's Fahrenheit i s c o l d ; i n w i n t e r , i t i s warm. But as we o r d i n a r i l y use these words, we assume the p e r t i n e n t context. 'On waking one winter day I look out the window and see the snow m e l t i n g . I exclaim, I t ' s warm outside I ' In the r e l e v a n t context, to say ' i t i s warm' i s to. imply t h a t 'the snow i s m e l t i n g ' . The- q u e s t i o n now remains — Do we mean anything more than the above when -we say tha t the warm weather i s causing the snow to melt. The two p o s s i b i l i t i e s are: I. warm weather i s a causal agent i i . warm weather e x p l a i n s the melt i n g of the snow i n the same sense th a t a c i d s i n the mouth e x p l a i n t o o t h decay i n terms of the concepts of physics and chemistry. We can r e j e c t i . o u t r i g h t as a misuse of 'agent 1, i i . c a r r i e s the f o r c e of a law ex p l a n a t i o n . 8 As we have seen from the previous a n a l y s i s , the question 'What caused i t ? ' , i s o f t e n answered hy an e x p l a n a t i o n of 'how i t occurred'. This appears to be the most complete answer i n so f a r as such explanations take i n t o account a l l f e a t u r e s which appear e s s e n t i a l f o r i t s production. Often, these explanations are given i n terms of laws or r u l e s . But, there i s something strange about'saying t h a t r u l e s cause e f f e c t s (events). Rules are made by men. They are spoken or w r i t t e n . They are not i n the world, f o r they have no temporal or s p a t i a l l o c a t i o n . N e v ertheless, asking f o r a cause turns out very o f t e n to be asking f o r an e x p l a n a t i o n . N. R. Hanson goes as f a r as to say t h a t , "The primary reason f o r r e f e r r i n g to the . cause of X i s to e x p l a i n X. There are as many causes of X as explanations of X." ; Let us suppose that there are n p o s s i b l e explanations of a car a c c i d e n t . Further i n v e s t i g a t i o n r e v e a l s to the magis-t r a t e t h a t according to ' r a t i o n a l ' c o n s i d e r a t i o n s , two of them are u n s a t i s f a c t o r y . Now, having a l l the p e r t i n e n t 'facts.'' before him, he advances a new ex p l a n a t i o n f o r the a c c i d e n t . Are we then to say tha t f i r s t there were n causes, then there were n-2 causes, and now there are n-1 causes f o r the accident?. I t i s c l e a r l y the case that 'causes' and E x p l a n a t i o n s ' do not have a one-to-one correspondence. I b e l i e v e t h a t we w i l l a l l r e a d i l y admit t h a t the explanations f o r the occurrence of some event may be many, may d i f f e r from day to day and may be c o r r e c t or not c o r r e c t . However, causes cannot be t r e a t e d i n t h i s way. The causes f o r yesterday's accident are not d i f f e r e n t today from yesterday. N e i t h e r are causes s a i d to be c o r r e c t .  9 or i n c o r r e c t , although, the cause of some event may or may not be c o r r e c t l y i n d e n t i f i e d . • • What does Hanson mean by 'explain'? We o f t e n ask, 'Explain why ?' and 'E x p l a i n how ?' To ' e x p l a i n why1 i n i t s primary sense Is to give purposes, motives and reasons. To ' e x p l a i n how' i s to give d e s c r i p t i o n s , o r i g i n s or to invoke some theory of o p e r a t i o n or some model. Suppose someone were to say that there i s a one-to-one correspondence between the c o r r e c t explanations and the causes f o r some p a r t i c u l a r , occurrence. To r e f u t e t h i s : a s s e r t -a t i o n , i t i s s u f f i c i e n t to p o i n t out tha t 'why' explanations are made in-terms which, as we have seen, are not causes. 10 "WHY QUESTIONS" CORRESPOND TO CAUSES ' AND "HOW QUESTIONS" CORRESPOND TO LAW-, LIKE EXPLANATIONS Even though questions i n science may be formulated i n terms of 'why', yet these questions are never answered by stating:: purposes or t e l e o l o g i c a l reasons. The answers which science gives to 'why' questions are never i n terms of purposes or reasons but i n terms of how X v a r i e s w i t h Y, how the atmosphere s c a t t e r s white l i g h t , how the p l a n t synthesizes sugars, e t c . I b e l i e v e 'why' remains i n use sin c e p r e - s c i e n t i f i c t h i n k i n g was o f t e n t e l e o l o g i c a l and i n v o l v e d agents as causes w i t h power to b r i n g about t h e i r e f f e c t s . So -in former times 'why questions' were a p p r o p r i a t e . The word has remained w i t h us although we no longer use i t i n i t s t e l e o l o g i c a l sense i n science. I t i s important f o r us to be c l e a r about (the c o n t r a s t between) the 'how' and 'why' type questions because the change from 'why' to 'how1 corresponds to a change from a.system of causes conceived as what Locke c a l l s 'powers' to a system of l a w - l i k e statements about the world. Where causes are thought .to have the power to b r i n g about t h e i r e f f e c t s 'why' questions are ap p r o p r i a t e . 'Why d i d P o c c u r ? 1 Answer: X had the power to produce P and X was present i . e . X caused P. On the other hand the question: 1 'How d i d P occur?' i s ' n o t s a t i s f a c t o r i l y answered by saying 'X caused P'. We can ask how d i d X cause P?' or, 'what i s the exact r e l a t i o n s h i p between X and P? 1 What i s being asked f o r i s the law r e l a t i n g to X and P. We can even begin to date the change between the two conceptions. Ernst Schumacher w r i t i n g on G a l i l e o ' s method f o r 11 conducting i n v e s t i g a t i o n s i n n a t u r a l science says a s - f o l l o w s : " G a l i l e o replaced the u n f r u i t f u l s p e c u l a t i o n s of 'why?' by an a n a l y s i s of 'how?' He recommended that the i n v e s t i g a t i o n of nature should no longer continue to i n q u i r e i n t o i t s substance but r a t h e r i n t o i t s f u n c t i o n ; the i n v e s t i g a t i o n s should concern themselves not w i t h the essences but w i t h the a t t r i b u t e s of nature. G a l i l e o c h a r a c t e r i z e d t h i s new method of viewing nature i n the t h i r d l e t t e r on sunspots to the (9) mayor of Augsburg, Markus Welser, dated 1613." I quote i n p a r t from t h i s l e t t e r : "For i n our s p e c u l a t i n g we e i t h e r seek to penetrate the true arid and i n t e r n a l ' e s s e n c e of n a t u r a l substances, or content'Ourselves w i t h a knowledge of some of t h e i r p r o p e r t i e s . The former I h o l d to be as impossible an undertaking w i t h regard to the .' c l o s e s t elemental substances, as w i t h more remote c e l e s t i a l things...' I know no more about the true essence of e a r t h or f i r e than about those of the moon or s u n . . . " ^ ^ . P. H. Nowell-Smith* w r i t i n g on c a u s a l i t y says much the same t h i n g : "The t r a n s i t i o n from explanations i n terms of e f f i c i e n t causes .to explanations i n terms of Law was l a r g e l y the work of G a l i l e o . . . I n the f i r s t place he undermined A r i s t o t e l i a n e xplanations of why things move as they do... This d i s c r e d i t e d the whole e n t e r p r i s e of e x p l a i n i n g phenomena i n terms of f i n a l causes and thereby opened the way f o r other types of explan-a t i o n . Secondly, the s u b s t i t u t i o n of exact d e s c r i p t i o n f o r e x p l a n a t i o n (or, as i t i s sometimes put, -of the question 'How?' f o r the question 'Why?') l e d e v e n t u a l l y to a conception 12 of science i n which a l l e x p l a n a t i o n j u s t i s description-. . A phenomena i s now s a i d to be explained when the r e g u l a r i t y which i t e x e m p l i f i e s i s able to be i n c o r p o r a t e d i n t o a (11) system of laws...." v ' The a n a l y s i s of 'how' and 'why' questions serves as an e x p l i c a t i o n of the Schumacher and Nowell-Smith views which are of paramount importance f o r understanding the r e l a t i o n s h i p between the two world accounts: ( i ) i n terms of causes, and ( i i ) i n terms of d e s c r i p t i o n s as l a w - l i k e accounts of the world. I wish to make t h i s s e p a r a t i o n of 'why?1 and 'how?' which estab-l i s h e s the method of science c l e a r . Let i t be understood, that the f o l l o w i n g d i s c u s s i o n of 'why?' and 'how?1 does not attempt to be a thorough language a n a l y s i s , but i t i s r a t h e r r e s t r i c t e d to c l a r i f y i n g the concepts of purposes and reasons as a s s o c i a t e d w i t h 'why?1 and 'how?' questions i n so f a r as they have bearing on my'thesis. Anatol Rapoport notes the c o n t r a s t i n the tasks of philosophy and t h a t of s c i e n c e . "Science confines i t s e l f to d e s c r i p t i o n s of how t h i n g s happen and does not pursue the more fundamental question of why t h i n g s happen as they do. I t does remain f o r (12) philosophy to i n v e s t i g a t e t h i s more fundamental q u e s t i o n . " . Whereas, science w i l l answer 'why* questions, i t w i l l do so by s t a t i n g t h a t some p a r t i c u l a r occurrence f a l l s under the form of a general law. In answer to. the q u e s t i o n , 'why d i d the apple f a l l ? ' science w i l l , say, 'because a l l bodies are a t t r a c t e d towards each other i n accordance w i t h the u n i v e r s a l law of g r a v i t a t i o n ' . To the question 'what caused the apple to f a l l ? ' the same answer w i l l be given. E s s e n t i a l l y , science answers only one question and'tha 1 3 i s the 'how' quest i o n , namely, 'How do bodies f a l l ? ' They f a l l i n accordance w i t h the u n i v e r s a l law of g r a v i t a t i o n . I wish to d i s t i n g u i s h between two uses of 'why', l a . Why d i d Brutus stab Caesar? b. Why d i d P r e s i d e n t John Kennedy de c l a r e a war on poverty? Here the answer i s given i n terms of the purposes or motives which the subject i s s a i d to have had. a. His purpose was to conserve the Roman Republic from the imagined usurper Caesar. b. His purpose or motive was to b u i l d a strong and j u s t America. The second use of 'why' i s i l l u s t r a t e d by the f o l l o w i n g two sentences: I l a . Why d i d the wine b o t t l e which one of Caesar^'s s o l d i e r s threw i n t o the Tiber at the l e f t bank end up on the < other side of the r i v e r ? b. Why i s the sky blue? • We note, f i r s t of a l l , t h a t the sentences l a . and b. change t h e i r meaning when 'how' i s s u b s t i t u t e d f o r 'why', or 'how d i d i t occur t h a t ' i s s u b s t i t u t e d f o r 'why'. That i s - "How'did Brutus stab Caesar?" or "'How; d i d i t occur that'' Brutus stabbed Caesar?" asks f o r the h i s t o r i c a l r e c r e a t i o n of the p h y s i c a l event, or i t asks f o r the preceding events which l e d to the stabbing. S i m i l a r l y l b . w i t h the s u b s t i t u t i o n of 'how' f o r 'why' now asks f o r an observer's account f o r what went on at that h i s t o r i c a l o ccasion. . ' I w i l l r e f e r to the use of 'why' which does not a l l o w a 'how' s u b s t i t u t i o n as the unique use. There i s a l s o a unique Ik use, i n the same sense, f o r 'how1, as we s h a l l see, where 'how' cannot be replaced by 'why'. Namely, the q u e s t i o n , "How does that mechanism work?", i s answered by e x p l a i n i n g how i t s v a r i o u s p a r t s i n t e r a c t . The qu e s t i o n , "Why does the mechanism work ( l i k e t h a t ) ? " , i s answered not 'how' the mechanism works ( s i n c e the i m p l i c i t ' l i k e t h a t ' a l r e a d y i m p l i e s knowledge of 'how'), but r a t h e r , "What d i d the maker of the machine or mechanism have i n mind f o r i t ? " P o s s i b l y , we can make t h i s even c l e a r e r . ; J Consider the sentence, "How f a r i s the moon?" O p e r a t i o n a l l y , what i s being asked here i s , "How many measuring s t i c k s have to be l a i d out to coyer the d i s t a n c e separating the moon and the earth?", or f o r some more advanced v a r i a n t of t h i s . I t i s c l e a r l y n o n s e n s i c a l to rephrase the que s t i o n to "'Why1 f a r i s the moon?" In I l a . s u b s t i t u t i n g 'how1 or 'how does i t occur t h a t ' f o r 'why' does not change the meaning of that sentence. I n l i b . "Why i s the sky blue?" or "How does i t - occur t h a t the sky i s blue?" are sentences which are not commonly used i n the E n g l i s h language. One i s not e x a c t l y c l e a r what i s being asked. The f o r c e of l i b . appears to be: "In v i r t u e of what process i s the sky blue?" Let us assume that we are asking a s c i e n t i f i c a l l y o r i e n t a t e d person why the sky i s blue. Then we would presumably be t o l d something l i k e : The - l i g h t from the sun, white l i g h t , i s a mixture of the v a r i o u s s p e c t r a l c o l o u r s , but the atmosphere s c a t t e r s the sho r t e r wave l e n g t h (blue) more than the longer wave le n g t h s . Consequently, we observe the sky as blue. Now, i f we consider t h i s answer apart from.the question which we asked, we. see i t as an e x p l a n a t i o n f o r the blueness of the sky. In p a r t i c -u l a r , we see that the e x p l a n a t i o n d e s c r i b e s how white l i g h t 15 o r i g i n a t i n g ' i n the sun i s s c a t t e r e d 'by the earth's atmosphere. We are not t o l d why any of t h i s happens. That i s , . t h e e x p l a n a t i o n i s an answer'to a 'how' q u e s t i o n ; although the q u e s t i o n which asks "How does i t occur t h a t the sky i s blue?" i s not commonly used. The 'why' question i s a remnant of a t e l e o l o g i c a l p r e - s c i e n t i f i c conception of the world. To conclude: The unique, use of 'why' which does not a l l o w an a l t e r n a t i v e 'how' question to do i t s work i s i n terms of • purpose, motives, reasons and p o s s i b l y f i n a l causes, i n v o l v i n g agents. S i m i l a r l y , 'how1 has.a proper use which.does not overlap w i t h the.'why' question. In u s i n g language, we o f t e n ask 'why?' but do not d i s t i n g u i s h t h i s 'why' question from the same question w i t h 'how' s u b s t i t u t e d f o r 'why'. Where 'why' questions are asked i h science the answer i s always i n terms of 'how', whether or not, as the i l l u s t r a t i o n which we have considered shows a d i r e c t 'how' s u b s t i t u t i o n i s i n common acceptable use. 16 CAUSES IN C. G. HEMPEL'S EXPLANATIONS C a r l Hempel and Paul Oppenheim w r i t i n g about explanations d i v i d e the b a s i c p a t t e r n of s c i e n t i f i c e xplanations i n t o two c o n s t i t u e n t statements, explanandum and explanans. . The explanandum de s c r i b e s the" phenomenon to be explained and the explanans accounts f o r the phenomenon. "The explanans f a l l s i n t o two c l a s s e s , one of these contains the sentences C^, Cg.-.C^ which s t a t e antecedent c o n d i t i o n s (l ^ V and a^ , a ^ . i.a.^ which represents general laws." -J/ Four l o g i c a l c o n d i t i o n s of adequacy are y given as f o l l o w s : (1) The explanandum must be l o g i c a l l y deducible from the i n f o r m a t i o n contained i n the explanans. . (2) The explanans must c o n t a i n general laws, and those must a c t u a l l y be r e q u i r e d f o r the d e r i v a t i o n of the explanandum. (3) The explanans must have e m p i r i c a l content i . e . i t must be capable, at l e a s t i n p r i n c i p l e of t e s t by experiment or .• o b s e r v a t i o n . (h) The explanans has to' be h i g h l y confirmed by a l l r e l e v a n t evidence a v a i l a b l e . "An e x p l a n a t i o n i s not f u l l y adequate unless I t s explanans, i f taken account of i n time, could have served as a b a s i s • (Ik) f o r p r e d i c t i n g the phenomena under c o n s i d e r a t i o n . " The" Hempel-Oppenheim view of the r e l a t i o n of explanations to causes are c l e a r l y brought to l i g h t i n ; che f o l l o w i n g q u o t a t i o n : " I f E d e s c r i b e s a p a r t i c u l a r event, then the antecedent circumstances described i n the sentences C^ > Cg.-.C^. may be s a i d j o i n t l y to 'cause 1 t h a t event... Statements such as 17 a|, a 2 . . . a r which_assert general and une x c e p t i o n a l connections . between;specified c h a r a c t e r i s t i c s of events are customarily-c a l l e d c a u s a l or d e t e r m i n i s t i c laws." v J J The c a u s a l i t y , which has been described- i n n a t u r a l s c i e n c e , i s not' o c c u l t or unknowable. This c a u s a l i t y i s founded upon answers to 'how q u e s t i o n s ' , . i n the p r e v i o u s l y considered sense, not'why questions'. ;,How questions'', are answered i . e . . ~ explanations are given i n science by showing t h a t the p a r t i c u l a r occurrence of some event i s p r e d i c t e d or i t s occurrence f o l l o w s i n accordance w i t h general laws from some e a r l i e r ( e a r l i e r i n the d e r i v a t i o n ) s i t u a t i o n . . From the preceding d i s c u s s i o n i t should be c l e a r t h a t i t i s not the aim of t h e o r e t i c a l science to di s c o v e r causes. The causes f o r some p a r t i c u l a r occurrence are the s i t u a t i o n s C p (^...C^ from which by means of the laws a^ , a 2 * * ' a r ^ e c 0 1 1 3 8 1 ! 1 1 8 1 1 0 9 5 o r e f f e c t s can be l o g i c a l l y deduced. In t h i s connection i t i s of i n t e r e s t to note the 19th century p h y s i c i s t K i r c h h o f f ' s views: •."In h i s work on mechanics he de c l a r e s t h a t i t ' s o b j e c t i v e i s not to d i s c o v e r the causes of motion; i t i s to desc r i b e completely and i n the simples t manner the motions which occur in" nature under s p e c i f i c conditions.»^^) As we have seen ;Hempel claims a symmetry between explanations and p r e d i c t i o n s . I wish b r i e f l y to i n q u i r e here, 'what are exp l a n a t i o n s ? ' The f u n c t i o n of e x p l a n a t i o n i s c l e a r l y " (in) as M i c h a e l S c r i v e n says to provide understanding. IJ Yet, understanding i s not always a consequence of an explanation.(we say I j u s t don't understand h i s e x p l a n a t i o n f o r the occurrence of X). Nor i s i t r e q u i r e d that explanations always be given f o r 1 8 understanding to. r e s u l t . I f I was t o l d that a wet a i r f r o n t was moving i n from the sea I would understand why i t i s r a i n i n g . That i s , given c e r t a i n f a c t s p e r t i n e n t to X we can o f t e n under-stand 'the occurrence of X. An e x p l a n a t i o n i s not given. Yet, i n a sense an e x p l a n a t i o n i s made. In order f o r an e x p l a n a t i o n t o be given i t would be r e q u i r e d t h a t a d e r i v a t i o n be made i n accordance w i t h general laws, from some given s i t u a t i o n , t h i s c o n s t i t u t e s the explanans statement. Given the f a c t t h a t moist a i r i s moving i n from the ocean and knowing the law t h a t : Whenever moist a i r moves i n from the ocean i t i s f o r c e d to r i s e over the mountains thus c o o l i n g the a i r and forming p r e c i p i t a t i o n , we can understand why i t i s r a i n i n g i n t h i s p a r t i c u l a r s i t u a t i o n . (We can understand what processes have taken place or are t a k i n g place.) Such understanding r e q u i r e d a knowledge of how r a i n i s brought-about and a knowledge that the r e q u i s i t e c o n d i t i o n s are here and now r e a l i z e d . Do we i n general r e q u i r e that laws should be invoked f o r an e x p l a n a t i o n ' o r i s i t s u f f i c i e n t f o r an e x p l a n a t i o n to be given when a p a r t i c u l a r i s subsumed under an e m p i r i c a l g e n e r a l -i z a t i o n ? Is i t an e x p l a n a t i o n to answer the q u e s t i o n , "Why d i d t h i s pen f a l l down?" by saying t h a t under a set of boundary c o n d i t i o n s a l l m a t e r i a l bodies f a l l ? The g e n e r a l i z a t i o n " a l l bodies f a l l " 'requires us to know that the p a r t i c u l a r object under c o n s i d e r a t i o n does so a l s o i . e . t h a t t h i s pen does so a l s o . I f •the p a r t i c u l a r body under c o n s i d e r a t i o n i s i n c l u d e d then the premise already assumes that which i s to be deduced. 19 The previous c o n s i d e r a t i o n s suggest t h a t an e x p l a n a t i o n i n terms of a p a r t i c u l a r occurrence f a l l i n g under a u n i v e r s a l i s f a u l t y . But, o f t e n , j u s t such explanations are u s e f u l and are i n f a c t accepted as s u f f i c i e n t e x p l a n a t i o n s . The a s s e r t i o n t h a t : "His 1953 Chevrolet 'broke down' when the recorded mileage was i n excess of e i g h t y .thousand m i l e s . " may be considered as being explained by showing t h a t ' a l l known automobiles of t h i s make do i n f a c t 'break down' a f t e r being d r i v e n i n excess of ei g h t y thousand m i l e s . Regarding the A r i s t o t e l i a n s y l l o g i s m J.S. M i l l w r i t e s : "The i n f e r e n c e i s f i n i s h e d when we have asserted that a l l men • are m o r t a l . "^"^ I t appears t h a t M i l l i s c o r r e c t i n saying we p e r p e t u a l l y reason from p a r t i c u l a r s to p a r t i c u l a r s . The p a r t i c u l a r men we know to have died serves as a reason or b a s i s f o r saying that some p a r t i c u l a r l i v i n g man i s m o r t a l . The intermediate general p r o p o s i t i o n may be construed as s e r v i n g or f u n c t i o n i n g as a statement f o r some f i n i t e sampling of i n d i v i d u a l s from which, i n f a c t , the reasoning to some other p a r t i c u l a r i s made. '• A l t e r n a t i v e l y , we can view the premise, " A l l men are m o r t a l " as being asserted w i t h a h i g h degree of p r o b a b i l i t y c o n d i t i o n a l l y upon the sta t e d premises. This l a t t e r i n t e r p r e t -a t i o n i s c o n s i s t e n t w i t h the Hempel t h e s i s i n that, a general p r o p o s i t i o n i s used i n the explanans. 2 0 EXPLANATIONS AND PREDICTIONS•IN QUANTUM MECHANICS In the realm of t h e o r e t i c a l science Hempel's symmetry .between explanations and p r e d i c t i o n s does seem to e x i s t . Only quantum mechanics casts s e r i o u s doubt on t h i s t h e s i s , but c o n t r a r y to views advanced by N. R. Hanson, even quantum mechanics d i s p l a y s t h i s symmetry. > N. R. Hanson i n an a r t i c l e ON THE SYMMETRY BETWEEN EXPLANATIONS AND PREDICTIONS a t t a c k s the Hempel t h e s i s t h a t , "the j u s t i f i c a t i o n of a p r e d i c t i o n of P i s symmetrical w i t h the e x p l a n a t i o n of P." He says "Only i n Newton's PRINCIPIA MATHEMATICA PHILOSOPHIAE NATURALIS does the f i n a l i d e a l which Hempel o u t l i n e s (19) seem f u l l y to -be r e a l i z e d . " v / y Hanson looks to quantum physics to f i n d a counter example or a realm of exception to Hempel's conception of e x p l a n a t i o n i n s c i e n c e . He w r i t e s , "The s i t u a t i o n i s , , however, t o t a l l y d i f f e r e n t i n quantum p h y s i c s . . . given any single-quantum phenomena P ( f o r example, the emission of a ^ - p a r t i c l e from a r a d i o a c t i v e substance or the s c a t t e r i n g of a ^-ray photon by an e l e c t r o n ) , P can be completely explained, ex post f a c t o ; one can understand f u l l y j u s t what happened, i n terms of w e l l e s t a b l i s h e d laws of the composite quantum theory...' These laws give the. meaning of e x p l a i n i n g s i n g l e micro-events... But i t i s , of course,' the most fundamental f e a t u r e of these laws that the p r e d i c t i o n of such a phenomenon P. i s , as a matter of t h e o r e t i c a l p r i n c i p l e , q u i t e i m p o s s i b l e . " Hanson repeats t h i s same c l a i m i n the a r t i c l e THE COPENHAGEN INTERPRETATION OF THE QUANTUM THE0RY ( 2 1 ) again without o f f e r i n g any argument f o r the c l a i m that quantum p h y s i c s ' e x p l a i n s ' 21 i n d i v i d u a l micro-events. To meet Hanson's o b j e c t i o n s we may f o l l o w two route s . We may w i t h E i n s t e i n , D e B roglie, Schrodinger and more r e c e n t l y (22) (1957) w i t h Bohmv ' argue that quantum mechancis i s not complete i . e . t h a t f u r t h e r study w i l l r e v e a l hidden parameters which w i l l a l l o w p r e d i c t i o n s to be made of the behaviour of i n d i v i d u a l fundamental p a r t i c l e s . A l t e r n a t i v e l y we may question whether or not i n f a c t quantum physics does e x p l a i n i n d i v i d u a l phenomena i n a sense i n which i t does not p r e d i c t these phenomena. I wish t o . pursue.the second l i n e of o b j e c t i o n , t h a t i s , to i n q u i r e i n what sense quantum physics e x p l a i n s and to i n q u i r e i f there i s not a corresponding sense of p r e d i c t i o n . N. R. Hanson w r i t e s , c o n t i n u i n g h i s c r i t i c i s m of the hidden parameter view, "There i s no i n t e l l i g i b l e way i n t h i s ' -— system (wave mechanics) of speaking of the p o s i t i o n of a h i g h speed e l e c t r o n and there i s no way i n t h i s system of forming p r e d i c t i o n s of c e r t a i n types of events ( f o r example, neutron emission from unstable carbon)." v J J This view or understanding of quantum mechanics does-not d i f f e r i n essence to Linus'.Pauling 1 conception. P a u l i n g w r i t e s , "Schrodinger' s system of dynamics d i f f ers:'from that of Newton, Lagrange and Hamilton i n i t s aim as w e l l as i t s . method. Instead of attempting to f i n d equations which enable a p r e d i c t i o n to be made of the exact p o s i t i o n s and v e l o c i t i e s of the p a r t i c l e s of a system i n a given s t a t e of motion, he devised a method of c a l c u l a t i n g a f u n c t i o n of the coordinates of the system and the time (and not the momenta' or v e l o c i t i e s ) , w i t h the a i d of which, i n accordance w i t h 2 2 the i n t e r p r e t a t i o n developed by Born, probable values the coordinates and other dynamical quantities can be (.2k) predicted f o r the system." x ' I wish to consider the physical (Born) i n t e r p r e t a t i o n of the Schrodinger wave function"\|r. In the one dimensional case ij/" i s a'function of x and t, i . e . \|/ (x,t) .. For a given value of the time t, l j / * ( x , t ) ( x , t ) , i . e . , the product of and i t s complex conjugate, i s a function defined f o r a l l values of x between - oo and + 0 0 ; that i s , throughout the con-f i g u r a t i o n of space of t h i s one dimensional system. I t i s the Born postulate that: r,The quantity \j/"*(x,t) 1 ^ (x,t)dx i s the p r o b a b i l i t y that the system i n the physical s i t u a t i o n repre-sented by the wave function \|/(x,t) have at the time t the configuration represented by a point i n the region dx of the configuration space.>'^25) "\|r * ( x ? t ) (x,t)dx i s the probabi-l i t y that the p a r t i c l e l i e s i n the region between x and x+dx at the time t . But i n talking about p a r t i c l e s or waves we are tal k i n g about macroscopic concepts. The solution to Schrodinger^ equation f o r a free p a r t i c l e i s of a sinusoidal character. Wave functions as obtained by a so l u t i o n of Schrodinger»s equation "give r i s e to experimental phenomena which are c l o s e l y similar to those associated in'macroscopic f i e l d s with wave functions. Neither view ( p a r t i c l e or wave) i s without l o g i c a l d i f f i c u l t i e s , i n as much as waves and p a r t i c l e s are macroscopic concepts which are d i f f i c u l t to apply to microscopic phenomena."^ ' The reason for adhering to the p a r t i c l e concept i n wave mechanical c a l c u l -ations i s simply to give a good i n t u i t i v e f e e l i n g f o r the mathematical r e s u l t s . 23 The f a c t i s that quantum mechanics, (the mathematical s t r u c t u r e ) does not e x p l a i n i n d i v i d u a l events any more than i t p r e d i c t s i n d i v i d u a l events, not because of some l i m i t a t i o n s i n ' the theory but because t h e . p a r t i c l e s aren't t h e r e . Both p a r t i c l e s .and waves are macroscopic concepts. We can f o r c e Hanson i n t o a dilemma. E i t h e r ( i ) the phenomena of experience-are explained by quantum mechanics or ( i i ) the phenomena of experience are explained i n terms of the concepts of c l a s s i c a l physics .in which meaning i s given s p e c i f i c a l l y to the concept of a p a r t i c l e at a p o i n t i . e . space at a given time i . e . P ( x , y , z , t ) . I f ( i ) i s adopted then i n d i v i d u a l events ( c l i c k s on.a Geiger counter) cannot be explained i n terms of quantum mechanics. I n d i v i d u a l events s a i d to be o c c u r r i n g at P ( x , y , z , t ) are not quantum mechanical concepts. A l t e r n a t i v e l y i f we adopt ( i i ) then meaning i s attached to the concept of a p a r t i c l e at ( x , y , z , t ) . But, c l a s s i c a l mechanics i s not competent to d e a l w i t h microphysics. Attempts at . e x p l a i n i n g black-body r a d i a t i o n and the p h o t o - e l e c t r i c e f f e c t showed the l i m i t a t i o n s of c l a s s i c a l mechanics. The quantum mechanical d e s c r i p t i o n of a p a r t i c u l a r p a r t i c l e according to the Born i n t e r p r e t a t i o n i s j u s t the | " \ | / ~ ^ p r o b a b i l i t y f u n c t i o n solved w i t h some s p e c i f i e d i n i t i a l c o n d i t i o n s . Suppose we are asked to e x p l a i n the. d i f f r a c t i o n of e l e c t r o n s by a c r y s t a l . A d e t e c t o r placed at a c e r t a i n angle i n d i c a t e s t h a t e l e c t r o n s are being r e c e i v e d - what i s the explan-a t i o n f o r t h i s observation? To account f o r the o b s e r v a t i o n we assume that what i s . . c a l l e d beam of e l e c t r o n s v i z . a wave of r E frequency y = r- f a l l s on the c r y s t a l , and we c a l c u l a t e the 2h i n t e n s i t y of" the waves s c a t t e r e d i n the d i r e c t i o n s p e c i f i e d . The r e s u l t of such a c a l c u l a t i o n i n d i c a t e s w i t h i n l i m i t s what the detector i s expected. ; to r e c o r d . ' I t i n d i c a t e s angles of hig h p r o b a b i l i t y and.low p r o b a b i l i t y f o r f i n d i n g e l e c t r o n s . I t i s the case, as Hanson says, that p r e d i c t i o n s of i n d i v i d u a l quantum phenomena.are q u i t e i m p o s s i b l e , but so are a l s o e x p l a n a t i o n s . Hanson .says' t h a t the . symmetry t h e s i s i s v i o l a t e d , since "...a Geiger counter i n t e r c e p t i n g ^ p a r t i c l e s from an unstable i s o t o p i c source, w i l l c l i c k i n a wholly u n p r e d i c t a b l e way. Once a p a r t i c l e has been emitted the counter's c l i c k i s determined c l a s s i c a l l y . But it . r e m a i n s c o n c e p t u a l l y untenable .to p r e d i c t when.a p a r t i c l e w i l l be emitted, and hence when the counter w i l l . n e x t c l i c k . . . I t s macrophysical c l i c k s (27) must be i n p r i n c i p l e u n p r e d i c t a b l e . " I J Hanson's mam e f f o r t . i s d i r e c t e d to denying the hidden parameter'view. My t h e s i s does not r e q u i r e a defence of the hidden parameter view. Whereas i t i s q u i t e c l e a r what quantum mechanics does not p r e d i c t i t i s not c l e a r what quantum mechanics i s s a i d by Hanson to e x p l a i n and what i n f a c t i t does e x p l a i n . On page 31, .' CONCEPT OF THE POSITRON, he says: . "A quantum t h e o r e t i c account of.these phenomena ( s i n g l e ' neutron emission from unstable carbon) does e x p l a i n , to a' considerable extent, what k i n d of p h y s i c a l events they are." From the preceding two quotations i t appears t h a t quantum mechanics i s r e q u i r e d to e x p l a i n ( i ) the u n p r e d i c t a b l e c l i c k s on a Geiger counter ( i i ) the emission of neutrons ( p a r t i c l e s ) from r a d i o a c t i v e m a t e r i a l . 25 To maintain h i s t h e s i s , then, Hanson must c l a i m t h a t b o t h . ( i ) and ( i i ) are explained by quantum mechanics. I t i s c l e a r l y not s u f f i c i e n t to say as Hanson does i n the preceding q u o t a t i o n "explained to a considerable extent" f o r then to main t a i n the symmetry, t h e s i s we would only have to say " p r e d i c t e d to a considerable extent." Hempel suggests only t h a t the symmetry i s between complete explanations and p r e d i c t i o n s . Let us t u r n to Hempel's own answer to Hanson's c r i t i c i s m : " I f the i n f o r m a t i o n that P has occurred were in c l u d e d i n the explanans', the r e s u l t i n g " account would be u n i l l u m i n a t i n g l y c i r c u l a r . . . And i f the explanans contains only statements about antecedent c o n d i t i o n s , plus a s t a t i s t i c a l law of r a d i o a c t i v e decay, then i t can show at best that the occurrence of P was h i g h l y probable; but t h i s a f f o r d s only an i n d u c t i v e - s t a t i s t i c a l e x p l a n a t i o n , which has the same l o g i c a l form as the p r o b a b i l i s t i c i . e . i n d u c t i v e , p r e d i c t i o n of P . " ( 2 8 ) Hanson does not, a p a r e n t l y , want to r e s t r i c t h i m s e l f to a s p e c i f i c statement of what he means by. 1 e x p l a i n ' . The •fo l l o w i n g he does say about e x p l a n a t i o n . A r i s t o t l e ' s cosmology made the cosmos "more i n t e l l i g i b l e to h i s contemporaries and, i n (29) some sense t h i s must count as ' e x p l a n a t i o n ' . " v / J Hanson i s p a r t i c u l a r l y i n t e r e s t e d i n what have counted as explanations i n the past, f o r example, L e i b n i z d i d not t h i n k the PRINCIPIA offered-explanations but served only as a mathematical p r e d i c t i n g device. To ' e x p l a i n ' i n the past, suggests Hanson, has been used as meaning: to r e l a t e to the i n t u i t i v e l y evident.' 'Post d i c t i o n ' does not always s a t i s f y these c o n d i t i o n s . 26 On page .1 i n the i n t r o d u c t i o n to the CONCEPT OF THE POSITRON Hanson w r i t e s , "The 'hole-theory' of the p o s i t i v e e l e c t r o n i s an e x p l a n a t i o n of t h i n g s l i k e p a i r c r e a t i o n and a n n i h i l a t i o n ; none the l e s s , as a matter of p r i n c i p l e , t h i s theory cannot p r e d i c t when any given p a i r w i l l he created." U n f o r t u n a t e l y Hanson does not f u r t h e r e l a b o r a t e , i n h i s w r i t i n g , e x a c t l y how t h i s theory ' e x p l a i n s ' . The few words devoted to the subject present an analogy w i t h a concrete s i t u a t i o n . I t i s not at a l l clear- what c o n s t i t u t e s the e x p l a n a t i o n . Continuous j?, emission spectrum i s s a i d to be explained by p o s t u l a t i n g n e u t r i n o s . Neutrinos are given the p r o p e r t i e s charge = .0, r e s t mass = 0, l i n e a r momentum = P, r e l a t i v i s t i c energy = PC, and angular momentum - ~k \ which are r e q u i r e d to e x p l a i n the continuous j% spectrum. On page-12+ Fermi i s quoted as saying: "The whole s t o r y about fundamental p a r t i c l e s i s th a t they show themselves to have j u s t those p r o p e r t i e s they must • have i n order to e x p l a i n the l a r g e - s c a l e phenomena which r e q u i r e e x p l a n a t i o n . . . The existence of the neutrino has been suggested as an a l t e r n a t i v e to the apparent l a c k of co n s e r v a t i o n of energy i n ^ d i s i n t e g r a t i o n . " ."What i s to be explained here i s the observed continuous ^ > spectrum. This i s done by p o s t u l a t i n g a new p a r t i c l e which c a r r i e s o f f the energy which has •to be accounted f o r i n order to s a t i s f y the co n s e r v a t i o n of charge, mass angular momentum and energy. Given t h i s .microphysical s t r u c t u r e i t seems c l e a r that an e x p l a n a t i o n f o r the observed continuous emission spectrum i s found -in micro p h y s i c s . I b e l i e v e , however, th a t one can p r e d i c t a continuous 27 . ^ spectrum where, we know tha t the energy l o s t i n the atomic d i s i n t e g r a t i o n would be shared between two p a r t i c l e s (the p o s t u l a t e d n e u t r i n o and the e l e c t r o n ) according to some s t a t i s t i c a l law. P o s t u l a t e s are o f t e n made in- science to a i d i n the e x p l a n a t i o n of phenomena i . e . the p o s t u l a t e d n e u t r i n o allowed an e x p l a n a t i o n to.be made of the continuous ^ emission spectrum. Yet, i t i s Important to. note the s t a t u s of p o s t u l a t e d . e n t i t i e s . Let us consider another p o s t u l a t e . I t was observed e a r l y i n the physical'work on heat t h a t 'heat energy' t r a n s f e r could be e a s i l y , understood by p o s t u l a t i n g that heat was a f l u i d ( c a l o r i c ) . Such phenomena as temperature e q u i l i b r i u m of two bodies i n contact could w i t h t h i s p o s t u l a t e be r e a d i l y understood i n terms of the more f a m i l i a r p r o p e r t i e s of f l u i d s . Then to e x p l a i n why two metal bars, one at a higher temperature T-g, the other at a lower temperature T^ ,. reached an e q u i l i b r i u m at some intermediate temperature T^ -, one would say that t h i s was a consequence of the behaviour of f l u i d s (they seek t h e i r own l e v e l ) . We, however, have learned from the t r i a l s of the past what i s to c o n s t i t u t e a f r u i t f u l or s i g n i f i c a n t p o s t u l a t e i n science. I t i s r e q u i r e d that such p o s t u l a t e s f u n c t i o n i n f u t u r e p r e d i c t i o n s , that f u t u r e experimental r e s u l t s can be p r e d i c t e d i n terms of the e a r l i e r p o s t u l a t e s . P o s t u l a t e s must not o n l y f a c i l i t a t e i n the making of explanations but must a l s o f u n c t i o n i n p r e d i c t i o n s . Furthermore we r e q u i r e that coherence should be maintained i n the d i s c i p l i n e . I n t r o d u c t i n g the f l u i d or c a l o r i c theory of heat i s to introduce i n c o n s i s t e n c i e s i n the sense i n which we introduce a f l u i d , c a l o r i c , which i s i n v a r i a n c e w i t h a l l known f l u i d s i n being without weight. (This" 28 i s a se r i o u s i n c o n s i s t e n c y i n so f a r as i t i s no longer under-standable how a wei g h t l e s s f l u i d can seek i t s own l e v e l . ) As I understand Hanson's o b j e c t i o n to the symmetry t h e s i s i t i s simply t h i s : We understand what happens when h i g h energy p a r t i c l e s emitted 'randomly 1 by r a d i o a c t i v e matter i n t e r a c t w i t h the measuring device producing a f l a s h which i s . a m p l i f i e d and recorded. I t i s q u i t e true t h a t the c o l l i s i o n of an e l e c t r o n w i t h an atom which brings the atom to a higher energy l e v e l and : -the eventual emission of a photon i s a quantum phenomena which i n f a c t c o n s t i t u t e s an "e x p l a n a t i o n of what goes on i n the counter." I b e l i e v e that t h i s i s what Hanson means when he says th a t quantum mechanics e x p l a i n s i n d i v i d u a l events. Yet, c l e a r l y , t h i s i s not the problem w i t h which we are g r a p p l i n g . Consider the analogy; one may understand p e r f e c t l y w e l l the mechanism or the process t h a t i s o c c u r r i n g when i t i s r a i n i n g without being i n the l e a s t aware why i t i s r a i n i n g at t h i s p a r t i c u l a r time and p l a c e . This understanding r e q u i r e s p r i o r knowledge of p a r t i c u l a r a i r c u r r e n t s , a i r moistures and temperatures, know-l e d g e which o f t e n enough i s n o t . a v a i l a b l e even to the meteorol-o g i s t . I t i s p o s s i b l e to know and to e x p l a i n what i s happening when i t i s r a i n i n g without being able to e x p l a i n why i t I s r a i n i n g here now. In quantum mechanics i t i s p r e c i s e l y the'here now"which i s not e x p l i c a b l e . Hanson claims t h a t there-are two consequences of accepting quantum mechanics, n e i t h e r of which I have any reason to r e j e c t and n e i t h e r of,which serves as a c r i t i c i s m of the Hempel-Oppenheim t h e s i s . They are ( i ) there i s no i n t e l l i g i b l e way i n t h i s system of speaking. 29 of the exact p o s i t i o n of an e l e c t r o n of p r e c i s e l y known energy. ( i i ) there i s no way i n t h i s system of forming p r e d i c t i o n s of c e r t a i n types of events ( i n d i v i d u a l quantum events). I f there i s no i n t e l l i g i b l e way i n t h i s system of speaking of' the exact p o s i t i o n "how then can i t make sense to say there i s an i n t e l l i g i b l e way to e x p l a i n p r e c i s e l y that which we cannot speak about?" • . . I wish to t u r n to some arguments i n Ern s t C a s s i r e r ' s DETERMINISM AND INDETERMINISM IN MODERN PHYSICS to make my case stronger. The e s s e n t i a l case f o r indeterminism i n C a s s i r e r ' s account centers on the f a c t t h a t knowledge of the i j / " f u n c t i o n at some time t , as t^"(x,t^) allows "v|r ( x , t ^ ) to be p r e d i c t e d f o r some l a t e r time t . The Schrodinger equation can only y i e l d a s i n g l e - v a l u e d , f i n i t e and continuous s o l u t i o n . There i s nothing indeterminant about the wave f u n c t i o n . C a s s i r e r w r i t e s : "When the theory of r a d i o a c t i v e decay d e c l a r e s that f o r every substance there e x i s t s a c e r t a i n p r o b a b i l i t y that an atom chosen at random will•decompose w i t h i n a randomly, chosen i n t e r v a l of time; when i t i s shown th a t there i s a d e f i n i t e e x p o n e n t i a l law governing the decay; when accor-d i n g l y the 'decay s e r i e s ' of v a r i o u s r a d i o a c t i v e f a m i l i e s are e s t a b l i s h e d - then these are a l l extremely p r e c i s e c o n c l u s i o n s , even though they say nothing about the f a t e of the i n d i v i d u a l atom and the p r e c i s e i n s t a n t of i t s d e c o m p o s i t i o n . " ^ ^ 30 The f a c t t h a t i n d i v i d u a l p r e d i c t i o n i s not p o s s i b l e i n quantum mechanics, does not e s t a b l i s h a counter example to the symmetry t h e s i s . P r e d i c t i o n s are p o s s i b l e i n quantum mechanics; f o r example, decay w i l l occur according to a d e f i n i t e exponen-t i a l law. To ask f o r a p r e d i c t i o n of an i n d i v i d u a l neutron v i z . p a r t i c l e i s to ask f o r something which i s not even a quantum mechanical concept. The Born i n t e r p r e t a t i o n speaks about the p r o b a b i l i t y of there being a p a r t i c l e i n a d e f i n i t e volume. The concept of a p a r t i c l e at a p o i n t i n space at some time P ( x , y , z , t ) has no counterpart i n quantum mechanics. C a s s i r e r i s i n agreement w i t h Planck's statement to the e f f e c t t h a t the problem "whether a c e r t a i n q u e s t i o n i s meaningful i n p h y s i c s , can never be a r r i v e d at a p r i o r i but always and s o l e l y from the p o i n t of view of a given theory, the d i f f e r e n c e between the d i f f e r e n t t h e o r i e s c o n s i s t i n g p r e c i s e l y i n the f a c t t h a t according to one theory a c e r t a i n q u a n t i t y i s observable i n p r i n c i p l e , or a c e r t a i n question i s p h y s i c a l l y ni) meaningful w h i l e according to the other i s n o t . " w ' Hanson h i m s e l f has s a i d t h a t p a r t i c u l a r C ^ atoms are i n d i s t i n g u i s h -able ( w i t h i n .a given theory i . e . quantum mechanics). So a l s o are the fundamental p a r t i c l e s . ( I t h i n k Hanson's reasoning i s c o r r e c t on t h i s p o i n t ) . W i t h i n quantum mechanics, i n d i v i d u a l C 1 ! + atoms are i n d i s t i n g u i s h a b l e . This i s granted by Hanson. I t f o l l o w s i n accordance w i t h the P l a n c k - C a s s i r e r view that w i t h respect to the theory, the question which atom emitted the ^ p a r t i c l e i s meaningless. Then, quantum theory does not e x p l a i n t h e . s i t u a t i o n of a p a r t i c u l a r atom e m i t t i n g a p a r t i c u l a r e l e c t r o n . , 31 An o b s e r v a t i o n may be made i n a 'bubble-chamber 1.of a t r a c k ; the t r a c k i s spoken of as having i t s o r i g i n i n the r a d i o a c t i v e m a t e r i a l which i s contained w i t h i n the chamber. A person possessing other i n f o r m a t i o n f a c t u a l and t h e o r e t i c a l i . e . knowledge what the p a r t i c u l a r r a d i o a c t i v e m a t e r i a l i s and presupposing a model .or theory of r a d i o a c t i v e decay may make the statement: - "A ^ - p a r t i c l e was emitted at 12:22, as measured on my watch from the' C'-^ sample." :He might f u r t h e r add that some p a r t i c u l a r C-^ atom underwent a decay r e a c t i o n w i t h the consequent l o s s of an e l e c t r o n . But the preceding statement cannot be t r a n s l a t e d i n t o quantum mechanical terms wh i l e p r e s e r v i n g the macroscopic concept " p a r t i c l e here now." In the quantum mechanical case the best we can do i s a s s e r t ' p a r t i c l e ' i s i n the volume element /XV . Only a value of the "Ap"function i s d e f i n e d . This means (Born i n t e r p r e t a t i o n ) that the explanandum i s a p r o b a b i l i t y i . e . the p r o b a b i l i t y that a We know the p r e d i c t i o n s of p r o b a b i l i t i e s are adequately handled by quantum mechanics. For t h i s reason i t i s c l e a r t h a t Hanson has not constructed a counter example or a realm of exception to the Hempel-Oppenheim conception of e x p l a n a t i o n i n scienc e . e s s e n t i a l f e a t u r e s of the concept of ex p l a n a t i o n . We e x p l a i n the presence of a gas by r e f e r r i n g to the behaviour of very small unobservable e l a s t i c p a r t i c l e s i n c o n t i n u a l motion. We e x p l a i n the formation of a p r e c i p i t a t e i n a t e s t tube by that dv - p r o b a b i l i t y that a p a r t i c l e ' i s i n the volume element A N / . Perhaps the foregoing d i s c u s s i o n has missed some 32 r e f e r r i n g to t h e ' i n t e r a c t i o n s of i o n s . I t i s M. Scriven's c l a i m t h a t : ,J,We are committed to e x p l a i n i n g macro-phenomena i n terms of micro-phenomena and thus must b e l i e v e t h a t the t r u t h s of the macro-level (whether o b s e r v a t i o n a l or statements about t h e o r e t i c a l e n t i t i e s ) can be accounted f o r i n .micro terms."^ He reasons that chemical r e a c t i o n s must be explained i n atomic terms since the l e v e l to which we t u r n f o r an e x p l a n a t i o n of• what we accept' 'as b a s i c data' i s p r e c i s e l y t h i s l e v e l . Suppose we wish to e x p l a i n the emission of a neutron, from some piece of r a d i o a c t i v e m a t e r i a l as recorded on a s c i n t i l l a t i o n counter at some time t . The explanandum i s a • macrophysical observable phenomenon. The explanans invokes the realm of m i c r o p h y s i c s . In order t o . s a t i s f y . t h e Hempel-Oppenheim c r i t e r i a f o r e x p l a n a t i o n , the e x p l a n a t i o n must s a t i s f y f o u r c o n d i t i o n s of adequacy. The f i r s t c o n d i t i o n s t a t e s t h a t the explanandum must be l o g i c a l l y deducihle from the i n f o r m a t i o n contained i n the explanans. The 'here now presence 1 of the neutron cannot be explained by quantum mechanics. On the other hand, i f the explanandum i s s t a t e d as the p r o b a b i l i t y of X then the f i r s t . c o n d i t i o n of adequacy i s s a t i s f i e d . Whereas i t may the the case that we e x p l a i n macro-phenomena i n terms of micro-phenomena i t does not f o l l o w that there i s or can be complete e x p l a n a t i o n s , i n Hempel's sense, f o r a l l macro-phenomena. In f a c t there does not e x i s t an e x p l a n a t i o n , i n terms of quantum mechanics, f o r i n d i v i d u a l events as ' p a r t i c l e here now'. The Hempel-Oppenheim t h e s i s remains i n t a c t . 33 CONCLUSION Although causes are e x p l i c i t l y mentioned i n s c i e n c e , t h e i r use i s r e s t r i c t e d to the p r a c t i c a l s c i e n c e s . They o n l y give a fragmentary account of the r e l a t i o n between occurrences or events i n the world. Science i n general serves to answer 'how questions',-as contrasted w i t h 'why questions'. Our knowledge of the world as given by a t h e o r e t i c a l science i s expressed by what . we c a l l p h y s i c a l laws. These laws are not f u n c t i o n s of the time, although, of course the laws describe the behaviour of phenomena i n time i . e . they a l l o w p r e d i c t i o n s and r e t r o -d i c t i o n s of f u t u r e and past occurrences. Hempel has l a b e l l e d these laws c a u s a l . Quantum mechanics maintains s t r i c t c a u s a l i t y i n the sense that l a t t e r s t a t e s of the f u n c t i o n are d e t e r -minable from i t s e a r l i e r s t a t e s . I t i s not s u r p r i s i n g t h a t accounts d e s c r i b i n g i n d i v i d u a l fundamental p a r t i c l e behaviour are not p o s s i b l e since such e n t i t i e s construed as i n d i v i d u a l mass p o i n t s having exact s p a c i a l coordinates at an i n s t a n t are f i c t i o n s . The i m p l i c a t i o n drawn from" t h i s I s that c a u s a l i t y as understood above, (present s t a t e s a l l o w knowledge of f u t u r e s t a t e s ) , i s preserved. 3>+ NOTES CD John Locke, ESSAY CONCERNING HUMAN UNDERSTANDING, (Dover P u b l i c a t i o n s , New Y o r k ) , Volume 1, Chapter XXVI, page 43^ (2) Bertrand R u s s e l l , MYSTICISM AND LOGIC, (Unwin Books, London, 1963), Chapter IX, page 132 . (3) ' A. Wilson and H. 0 . S c h i l d , APPLIED PHARMACOLOGY, (Ninth E d i t i o n , C h u r c h i l l L t d . , London, 1 9 5 9 ) , page l 8 l (4) . G i l b e r t R y l e , THE CONCEPT OF MIND, (Barnes and Noble, • • New York, 1964 e d i t i o n ) , . Chapter IV, page 110 . (5) ;'• I b i d , page 113 (6) I b i d , Chapter I I , page 43 (7) R. W. Ditchburn, LIGHT,- ( B l a c k i e and Son L t d . , London, 1 9 6 1 ) , Chapter' 17 , S e c t i o n 6, The Rutherford-Bohr Atom, page J?VM-(8) N. R. Hanson, PATTERNS OF DISCOVERY, (Cambridge, Eng., U n i v e r s i t y P r e s s , 1958) , page 5^ (9) Ernst Schumacher, DER-FALL GALILEI, ( /The Case of G a l i l e i / , B e r l i n , 1964, my t r a n s l a t i o n ) , page 31 (10) G a l i l e i G a l i l e o , DISCOVERIES AND OPINIONS OF GALILEO, (Doubleday e d i t i o n , 1957? T r a n s l a t e d by Stilman Drake), pages 123-4-(11) P. H. Nowell-Smith, ENCYCLOPAEDIA BRITANNICA, ( 1 9 6 5 ' e d i t i o n ) , page 106 (12) Anatol Rapoport, OPERATIONAL PHILOSOPHY, (Wiley and Sons, New York, 1 9 6 5 ) , Chapter 5 , page 51 (13) C. G. Hempel and P. Oppenheim, THE LOGIC OF EXPLANATION, (Reprinted from the Philosophy of Science, 19^8, i n F. F e i g l and M. Brodebeck READINGS IN THE PHILOSOPHY OF SCIENCE, New York, Appleton-Century-Crofts, I nc., 1953), page 321 (14) I b i d , page 323 (15) I b i d , page 324 (16) V. F. Lenzen, CAUSALITY IN NATURAL .SCIENCE, (C. Thomas, S p r i n g f i e l d , I l l i n o i s , 1 9 , page 12 (17) M. S c r i v e n , NEW ISSUES IN THE LOGIC OF EXPLANATION, (PHILOSOPHY AND • HISTORY, S. Hook e d i t o r , New York, U n i v e r s i t y P r e s s , 1 9 6 3 ) , page 340 35 . 0 8 ) J . S. M i l l , A SYSTEM OF LOGIC, (Longmans, Green and Co., London, 1900), Book I I , Chapter. I l l 0 9) N. R. Hanson, ON THE SYMMETRY BETWEEN 'EXPLANATIONS AND PREDICTIONS^ (The P h i l o s o p h i c a l Review, 1959, 68), page 351 (20) ' I b i d , page 351 (21) • N. R. Hanson, THE COPENHAGEN INTERPRETATION OF THE • QUANTUM THEORY, (Reprinted in"PHILOSOPHY OF SCIENCE, S. Morgenbesser". and E. N a g e l ) 5 page h-63 (22) D. Bohm, A PROPOSED EXPLANATION OF QUANTUM THEORY ' IN TERMS OF HIDDEN VARIABLES AT A SUB-QUANTUM-MECHANICAL LEVEL (OBSERVATION AND INTERPRETATION, e d i t e d by S. Kdrner, London, 1957)? pages 33-^ +1 (23) N. R. Hanson, ON THE SYMMETRY BETWEEN "EXPLANATIONS AND PREDICTIONS, (The p h i l o s o p h i c a l Review, 1959), • page (2*f) Linus C a r l P a u l i n g , INTRODUCTION TO QUANTUM MECH ANICS, (McGraw-Hill, New York, 1935), page 51 ^ (25) I b i d , pages 6*f-5 (26) I b i d , page 93 (27) N..R. Hanson, THE CONCEPT OF THE POSITRON, (Cambridge, Eng., U n i v e r s i t y P r e s s , 1963), page 55 (28) C. G. Hempel, ASPECTS OF SCIENTIFIC EXPLANATION, (Free Press, 1956), page 0^7 (29) N. R. Hanson, THE CONCEPT OF THE POSITRON, (Cambridge, Eng., U n i v e r s i t y P r e s s , 1963), page 26 (30) Ernst C a s s i r e r , DETERMINISM AND INDETERMINISM IN MODERN PHYSICS, (Oxford U n i v e r s i t y P ^ s s , 1956 e d i t i o n ) , page 118 . . (3D I b i d , page 126 (32) M. S c r i v e n , DEFINITIONS, EXPLANATIONS AND THEORIES, (Volume I I , MINNESOTA STUDIES IN THE PHILOSOPHY OF SCIENCE, 1958, H. F e i g l , M. S c r i v e n and G. Maxwell), pages 99-195 36 BIBLIOGRAPHY Bohm, D 1957 A PROPOSED EXPLANATION OF QUANTUM THEORY IN TERMS •'. OF HIDDEN VARIABLES AT A SUB-QUANTUM-MECHANICAL . LEVEL, p r i n t e d i n Observation and I n t e r p r e t a t i o n , London, Butterworth's S c i e n t i f i c P u b l i c a t i o n s -C a s s i r e r , E. 1956 DETERMINISM AND INDETERMINISM IN MODERN PHYSICS, Oxford U n i v e r s i t y Press ; • . Ditchburn, R. W. 1961 LIGHT, London, B l a c k i e and. Son L t d . G a l i l e i , G a l i e l e o 1957 DISCOVERIES AND OPINIONS OF GALILEO, t r a n s l a t e d by S. Drake, Doubleday e d i t i o n . Hanson, N. R. 1963 THE CONCEPT OF TH"E POSITRON, Cambridge U n i v e r s i t y Press 1960 THE COPENHAGEN INTERPRETATION OF THE QUANTUM THEORY, Reprinted- i n S. Morgenbesser and E. Nagel, PHILOSOPHY OF SCIENCE 1959 ON,THE SYMMETRY BETWEEN EXPLANATIONS AND PREDICTIONS, The P h i l o s o p h i c a l Review, 1959 1958 PATTERNS OF DISCOVERY, Cambridge U n i v e r s i t y Press Hempel, C. G. 1958 THE LOGIC OF EXPLANATION, Philosophy of Science, 1958 1956 ASPECTS OF SCIENTIFIC EXPLANATIONS, Free Press Lenzen, V. F. 195*+ CAUSALITY IN NATURAL SCIENCE, C. Thomas, S p r i n g f i e l d , I l l i n o i s ^ Locke, John ESSAY CONCERNING HUMAN UNDERSTANDING, Dover P u b l i c a t i o n , New York 37 M i l l , J . S. 1900 A SYSTEM OF LOGIC, Longmans, Green and Co. L t d . , London Nowell-Smith, P. H. 1965 CAUSALITY, Encyclopaedia B r i t a n n i c a P a u l i n g , L i n u s , C a r l 1935 INTRODUCTION'TO QUANTUM.MECHANICS, McGraw-Hill, New York R u s s e l l , B. 1963 MYSTICISM AND LOGIC, Unwin Books, London Ryle, G i l b e r t 196U- THE CONCEPT OF MIND, Barnes and Noble, New-York Rapoport, A. 1965 OPERATIONAL PHILOSOPHY, Wiley and Sons, New York Schumacher, E. 196^ DER-FALL GALILEO, B e r l i n S c r i v e n , M. 1963 NEW ISSUES IN TH E=LOGIC OF EXPLANATION, i n Philosophy • and H i s t o r y , S. H o o k , e d i t o r , New York, U n i v e r s i t y Press 1958 DEFINITIONS, EXPLANATIONS AND THEORIES, Volume I I , Minnesota Studies i n the Philosophy of Science. W i l s o n , A. 1959 APPLIED PHARMACOLOGY, C h u r c h i l l L t d . , London 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0104684/manifest

Comment

Related Items