OPINION AND PROBABILITY 263 



with the verdict. Yet cases have occasionally occurred in which 

 it was afterwards proved beyond all shadow of doubt that the con 

 demned man was innocent of the crime. What do such facts 

 prove? That the human mind is incapable of attaining to genuine 

 certitude ? No ; but only that it is not infallible in the weighing 

 and testing of evidence; that even when men have exercised 

 what is commonly considered to be sufficient care, caution, and 

 prudence, they may embrace what is erroneous. And such oc 

 casional failures will teach prudent men to be still more cautious 

 in deciding grave issues on &quot; practical &quot; certitude. 



263. PROBABLE ARGUMENTS : THE ARISTOTELEAN ENTHY- 

 MEME. Among the many kinds of judgments which call for a 

 probable assent, the following are the more important classes : 

 (i) some of our interpretations of the immediate data of our sense 

 experience ; (2) some judgments whether universal, singular, or 

 particular based on the motive of human testimony ; (3) induc 

 tive generalizations from sense-experience, by way of enumerative 

 induction, analogy, or unverified hypothesis ; (4) conclusions de 

 rived by deductive inference from probable premisses ; (5) to which 

 may be added judgments reached by the application of the calculus 

 of probability (266-8). 



These various sources of probability do not reveal any new 

 forms of inference. When probability is reached by inference, the 

 obstacles to a certain assent lie not in the form but in the matter 

 of the inferential process. With many of those sources of prob 

 ability, as, for instance, those of the third class just mentioned, we 

 are already familiar. Indeed, the main sphere of probability is to 

 be found in induction. Before reaching a certain, scientific know 

 ledge of the inductively established general law, we have to pass 

 through many stages where our knowledge of it amounts to a 

 greater or smaller probability. All those various steps we have 

 already examined : the rough empirical generalizations from enu 

 merative induction, the arguments from example and analogy, 

 suggestions of more or less probable hypotheses, and, finally, 

 the processes of analysis, and the methods of experiment, by 

 which we seek to verify those probabilities and transfer them 

 into the sphere of certainties. 



Judgments derived from the first source mentioned above do 

 not seem at first sight to involve any inference at all. But sense 

 experience is, as a matter of fact, invariably accompanied not only 

 by judgment or interpretation, but also by inference (238). This 



