CAUSALITY 



CAUSTICS 



29 



the effect is produced. Thus it is noticeable that 

 while the former or more complete definition 

 <-i)iTt>spondri with that expressly given in J. S. 

 Mill's l.oific, hi inductive methods are entirely 

 devoted to explaining modes of discovering causes 

 in the narrower or popular signification. 



It is in this meaning of the term that science 

 investigates causes. In doing so, it goes on the 

 I in -supposition that every event or change has a 

 cause. This has been called the Law of Uni- 

 versal Causation, and may be expressed by 

 saying that the explanation of every event is 

 to be found in antecedent conditions. Scientific 

 investigation also presupposes the Law of the 

 Uniformity of Nature, that the same conditions 

 or cause will be followed (at all times and places) 

 by the same effects. The grounds and mutual j 

 relation of these two assumptions form the chief 

 subject of controversy in the philosophical theory 

 of causality. It is to Hume that the credit is due 

 of having drawn attention to the difficulties in- 

 volved in the principle of causation, in such a way 

 as to determine the whole course of subsequent 

 philosophy. All reasoning about matters of fact, 

 he shows all physical science, therefore depends 

 on the relation between cause and effect. Yet, 

 between the cause and the eflect there is no dis- 

 coverable connection. ' There appears not, through 

 all nature, any one instance of connection which is 

 conceivable by us. All events seem entirely loose 

 and separate. One event follows another ; but we 

 never can observe any tie between them. They 

 seem conjoined, but never connected. 1 Hume's own 

 solution of the difficulty is found in the law of 

 mental association. 'The mind,' he says, 'is 

 carried by habit upon the appearance of one event 

 to expect its usual attendant, and to believe that 

 it will exist. This connection, therefore, which we 

 feel in the mind, or customary transition of the 

 imagination from one object to its usual attendant, 

 is the sentiment or impression from which we form 

 the idea of power or necessary connection. Nothing 

 further is in the case. . . . When we say, there- 

 fore, that one object is connected with another, we 

 mean only that they have acquired a connection in 

 our thoughts, and give rise to this inference by 

 which they became proofs of one another's exist- 

 ence : a conclusion which is somewhat extra- 

 ordinary, but which seems founded on sufficient 

 evidence.' The conclusion to which Hume is 

 driven is thus that, while all reasoning about 

 matters of fact is founded on the principle of 

 causality, this principle has itself no other basis 

 than the mental tendency to pass from one impres- 

 sion to the idea of another impression previously 

 experienced in conjunction with the former. 

 Hume's solution is thus not sceptical (except as 

 regards the application of causality or any other 

 principle beyond experience), but it is subjective : 

 the connection of things is resolved into a customary 

 succession of ideas. Of the numerous theories of 

 causation put forward since the question was thus 

 opened, the two most important are J. S. Mill's 

 rehabilitation of Hume's doctrine to suit the re- 

 quirements of scientific investigation, and the 

 opposed doctrine of Kant and his philosophical 

 successors. 



It is characteristic of Mill's doctrine that the 

 principle of causality is made a consequence of the 

 Law of the Uniformity of Nature : ' the familiar 

 truth that invariability of succession is found by 

 observation to obtain l>etween every fact in nature 

 and some other fact which has preceded it. ' This 

 principle, which is assumed in every scientific in- 

 duction, is itself held to be the generalisation of a 

 wide and uncontradicted experience. 



A different position is given to the causal prin- 

 ciple in Kant's philosophy. The Scottish philoso- 



phers and others, as well an Kant, had attempted 

 replies to Hume, contending that causality JM an 

 intuitive judgment antecedent to experience. But 

 such a reply remains an arbitrary assertion until it 

 is shown how the causal judgment in connected 

 with experience. In Kant's Critiqtie of Pure 

 Reason this connection is thoroughly investigated ; 

 the refutation of Hume is only part or consequence 

 of a complete inquiry into the relation of reason 

 to experience. It was, however, largely Hume's 

 doctrine of causality that led to Kants new point 

 of view, and to the doctrine that experience IH the 

 product of the understanding, the realisation of it - 

 a priori forms. It is not the sequence of events in 

 time, Kant holds, that gives rise to the principle of 

 causality ; but the pure notion of causality finds 

 its realisation in this time-sequence, in which each 

 event is determined by its antecedent. Kant's 

 doctrine, as thus stated, is in full harmony with 

 the principles and methods of modern science ; 

 asserting the principle that every change i.e. each 

 successive state of the universe is the result of its 

 preceding state, and at the same time leaving to 

 empirical investigation the connection in experi- 

 ence of any one definite thing with any other. 



The most important discussions of causality are 

 those of Hume, Treatise of Human Nature, book L 

 part iii., and Essay Of the Idea of Necessary 

 Connection ; Kant, Critique of Pure Reason ; and 

 J. S. Mill, System of Logic, book iii. chaps, iii.-v. 

 There is also elaborate treatment of the subject in 

 the works of Reid, Stewart, and Hamilton. Dr 

 Thomas Brown's Inquiry into the Relation of 

 Cause and Effect contains much acute analytical 

 thinking. 



Cause Celebre, a convenient French term for 

 a specially interesting and important legal trial, 

 criminal or civil, such as the Douglas Cause 

 (1769-71), the Dred Scott case in the United 

 States as to the possession of a negro (1856), the 

 Tichborne case ( 1871-74). There is a great French 

 collection of Causes Celebres et interessantes (22 vols. 

 1737-45 ), by Gayot de Pitaval, with modern con- 

 tinuations. See TRIAL. 



Causerie, a name applied to a somewhat short 

 and informal essay on any subject in a newspaper 

 or magazine. More familiar in manner and slighter 

 in structure than the formal essay as usually under- 

 stood, it is an excellent medium for a writer whose 

 personality interests the reader as much as the 

 value of his thoughts. The name owes its literary 

 currency mainly to the famous Catiseries du Lundi 

 of Sainte-Beuve ; hardly less valuable examples 

 were many of Matthew Arnold's occasional essays. 



Causses, LES. See FRANCE (p. 770), and Bar- 

 ing-Gould's Deserts of Southern France ( 1894). 



Caustic (Gr., ' burning'), a term for substances 

 that exert a corroding action on the skin and flesh. 

 Lunar caustic (so called because silver was called 

 luna, ' the moon,' in the alchemists' mystical 

 jargon) is nitrate of silver, and common caustic is 

 potash. When used as a caustic in medicine, 

 the substance is fused and cast into moulds, 

 which yield the caustic in small sticks the thick- 

 ness of an ordinary lead pencil, or rather less-. 

 Caustic is also used in chemistry in an adjective 

 sense thus caustic lime, or pure lime, CaO, as 

 distinguished from mild lime, or the carbonate of 

 lime, CaCO,, caustic magnesia, MgO, and mild 

 magnesia, MgCO 3 , caustic potash, caustic soda (for 

 these, see POTASH, SODA, &c.). See CAUTERY. 



Caustics. When the incident rays are parallel 

 to the principal axis of a reflecting concave mirror, 

 they converge, after reflection, to a single point, 

 called the principal focus. In the case of parabolic 

 mirrors this is rigorously true. For, as is easily 

 seen from the fundamental property of the para- 



