4 SCIENTIFIC METHOD 



future, as when we deduce a particular eclipse ; in 

 the past, as when we deduce a particular animal from 

 fossil remains : in the present, as when we deduce that 

 this glass of water contains an innumerable number of 

 molecules of oxygen and hydrogen. 'It is not by in- 

 duction but by deduction that we know definite \ 

 particulars beyond experience in the future, in the 

 past, and even in the present^ 



All inference then begins from, and proceeds beyond, 

 experience. Yet it is common among philosophers to re- 

 duce knowledge to mere experience, and define science as 

 systematic experience. System, yes : the very difference 

 between ordinary and scientific knowledge is that while 

 the former is sporadic, the latter is systematic. As 

 Aristotle said, every science selects a subject, such as 

 number in arithmetic, magnitudes in geometry, investi- 

 gates as many propositions of its subject as possible, 

 and aims at last in bringing the multitude of propositions 



v under a few principles, in order to convert its whole 

 knowledge of the subject into a system. Science, Jtlxen 

 is systematization. But it is not mere systematic ex- 

 perience, but also systematic inference from, and beyond, 

 experience. , The science of the moon, for example, 

 must start from its visible face. But, as the moon 

 rotates only once in a revolution round the earth, it 

 shows us only one face, of which alone we have ex- 

 perience. How then do we know that it has another 



v side always turned from us, and in fact that it is a 

 sphere ? Not by experience, but by inference from 

 \ experience of other spheres. ' Science then is systematic^ 

 | knowledge by experience and inference., 



Now Scientific method is merely the way, or ways, of 



using different orders of inference in investigating any 



subject of science with a view to its system., Sometimes, 



