400 THE SCIENCE OF LOGIC 



It would be superfluous to show how far this abstract symbolism falls 

 short of picturing the complexity of the concrete facts and processes it is 

 supposed to represent. Nor is it of sufficient importance to call for any ela 

 borate attempt at improvement. Logicians have, however, improved it in 

 various ways, while pointing out its many shortcomings. 



The separation of the elements into antecedents and consequents has to 

 be effected by the investigator ; and he must bear in mind that the actual 

 influence of the cause is not prior in time to, but is simultaneous with, the 

 actual production of the effect. To illustrate these points, we may instance Dr. 

 Venn s manner of symbolizing the Joint Method : l 



&quot; Surely what we want is something of the following kind. Let x be 

 some phenomenon in regard to which eleven antecedents, viz. A to K are to 

 be taken account of, and suppose that we have collected the following sets of 

 affirmative and negative instances : 



Affirmative Negative 



ABCDE BCFG 



ADEFG DEHI 



AFGH I FG J K 



A H I J K HIDE 



&quot; It is clear that A is the only element, of the given lot of eleven, which is 

 always present in the former set of instances, and the only one which is always 

 absent in the latter set. If we knew for certain that there could be only one cause, 

 then clearly A is that one. So much indeed is established by the affirmative 

 instances. What the negative instances do is to disprove one after another 

 of the alternative causes other than A. It might be that A was not a cause 

 at all, but that B, D, F, and H had respectively been at work in producing x 

 in the four cases in question. The negative instances disprove this, however ; 

 and since they take account of every one of the ten letters, or cause symbols, 

 B to K, and show that no one of these is operative, we are led to conclude 

 that A alone is the cause which we are seeking.&quot; 



A theoretical knowledge of the method of inductive analysis, 

 by way of observation, experiment, and hypothesis, will help the 

 scientific investigator in his work ; but it will not determine for 

 him which, or how many, of the rules of elimination he must em 

 ploy in any given subject-matter, or in what order. This can be 

 determined only by his own insight, prudence, and knowledge of 

 the facts with which he is dealing. The progress of scientific dis 

 covery involves the use of all of them. 



We may give here the following final example, which will illustrate the 

 combination of three of the &quot; methods &quot; to form a series of positive and negative 

 experiments for the purpose of verifying the hypothesis that life proceeds only 

 from life, and never appears by spontaneous generation : 2 Let us assume that 

 the reputed &quot; spontaneous &quot; production of minute living organisms is really due 



1 Empirical Logic, pp. 430-1. 



2 They are the experiments actually performed by Pasteur. Cf. JANET, Traite 

 de philosophie, n. 146. Paris, Delgrave, 1879. 



