120 PART II. SOME IMPORTANT METHODOLOGICAL TERMS. 



Aristotle's syllogism can neither be identified with the induc- 

 tive nor altogether with the deductive method. This is owing 

 to the fact that not only is the mode of obtaining major pre- 

 mises regarded as alien to the subject, but no provision is made, 

 outside the reasoning process itself, for substantiating the con- 

 clusion reached. Strictly speaking, it represents a mode of 

 testing a statement as to its consistency with a more general 

 proposition, and may be said to be applicable where major and 

 minor premise are already demonstrated. 1 



Generalisation begins with the examination of the data. With 

 deduction the opposite obtains, i.e., examination principally 

 concerns itself with the verification of the deduction. With 

 this stage reached, the main scientific process of investigation 

 is completed on the theoretical side, save in so far as new 

 investigations are suggested. Jevons truly says: "The in- 

 vestigator begins with facts and ends with them. He uses facts 

 to suggest probable hypotheses; deducing other facts which 

 would happen if a particular hypothesis is true, he proceeds 

 to test the truth of his notion by fresh observations." (The 

 Principles of Science, p. 509.)- 



1 For instance, the following would be a correct syllogism: 



All men are immortal; 



My dog Cato is a man; 



Therefore my dog Cato is immortal. 



Or, All multicellular beings are unicellular; 



This mathematical point is a multicellular being; 

 Therefore this mathematical point is unicellular. 



- A knowledge of facts makes a profound difference to the nature of a 

 hypothesis and to the possibility of proving it or disproving it with fair ease. 

 We may illustrate this from Arrhenius' theory of panspermia. Desirous of 

 proving that life may have reached our globe from other spheres, he assumes 

 that life might be transferred from world to world in the form of micro- 

 scopically minute spores. He states that the rate at which such a spore would 

 fall is so small that favourable upward currents of air could waft it upwards 

 a hundred miles, to the limit of our atmosphere. There it might take up 

 negative electricity, and be driven out into interplanetary space by other 

 particles positively charged. Then the radiation pressure of the sun would 

 drive it out into stellar space. Finally, it might find a resting place, aftei^ 

 travelling for some thousands of years, and there it might introduce life or 

 augment the existing life. Each step in this theory of Arrhenius, including 

 the assumption of the existence of microscopic spores, is based not on bare 

 suppositions, but on scientific knowledge of the first order, and in this 

 Arrhenius only follows the common practice among scientists. If the spores 

 and the other circumstances had been merely postulated, we should have 

 had an illustration of the ancient and useless conception of a deduction. 

 Mendelyeffs assumption that the ether is a chemical element incapable of 

 forming combinations, is similarly deduced from recent enquiries which in- 

 dicate that such inert elements exist. 



Here are instances where the basis of the reasoning is of a very hypo- 

 thetical character. "Of supposed structural life units there is a great variety. 

 Besides the gemmules of Darwin, there were the physiological units of 

 Herbert Spencer. Professor Haeckel . . . has structural units of his own which 

 he terms plastidules. . . . Then came Nageli, the great botanist, who spoke 



