Stoney — Natural Science and Ontology. 513 



thesis that will help the inquirer forward, and which may then 

 become susceptible of revision and correction. Numberless in- 

 stances can be given in which this process has led to valuable 

 results. In fact, most of man's scientific knowledge of Nature 

 is owing to it. But such a method is repugnant to the philo- 

 sophical sceptic, whose attitude damps all advance unless it can be 

 carried on from the beginning under conditions of perfection — in 

 other words, under conditions which are impossible in the early- 

 stages of almost every inquiry. 1 



Accordingly I shall venture to adopt as a postulate in the rest 

 of this essay, the premiss that every event that occurs in the 

 autic universe is caused — since this fertile postulate is eminently 

 fitted to enable us to push forward in our inquiry, since also its 

 truth is already probable, and since the evidence for it will receive 

 great (I had almost said abundant) confirmation as we advance. 

 If, however, anyone prefers, he need go no further than admit 



1 This statement may be carried farther. I know of no justification (of the kind 

 demanded by the philosophical sceptic) for my relying on memory as showing that past 

 states of my mind existed. "What the sceptic permits himself to believe should accord- 

 ingly, if he is consistent, go on shrinking till nothing is left but the present phase of 

 his own ego — if even that remains. 



The philosophical sceptic begins by refusing to venture in company with any of his 

 beliefs in reference to which he does not at once see justification for his mind being in 

 the attitude called philosophical certitude. He then attempts to make such petty ex- 

 cursions as he can within the narrow limits thus laid down. 



The scientific method of investigating the validity of our beliefs is entirely different. 

 In it our existing beliefs are taken as our starting point, or a careful selection from them 

 is made with a view to our employing only those that involve the least onerous assump- 

 tions, and which at the same time are fitted to enable us to advance. After the legitimate 

 consequences of these have been worked out, the inquirer finds himself in a better 

 position to return and test the validity of the bases on which he had proceeded. After 

 this revision, and such corrections as he finds possible, he makes a step of a like kind 

 farther forward ; after which another revision and another advance. Thus real progress 

 is accomplished. Probabilities acquire strength and accumulate ; and in the end a state 

 of mind is attained replete with knowledge of the realities within and around us. 



The sea of knowledge on which man makes his brief voyage is for the most part 

 unfathomable. He cannot hope except near shore to measure the whole depth, and 

 thus attain philosophical certainty. But the scientific student may diligently use such 

 a sounding line as he possesses — that of probability — and with it explore wide ex- 

 panses under which there are no rocks or shoals within the utmost depth that he can 

 plumb, and over which he may securely sail. 



Compare this with the situation of the philosophical sceptic, groping among rocks 

 along the shore, and not venturing beyond the shallow margin which he can probe with 

 his little pole. 



