SCIENCE AND DEMONSTRATION 227 



Aristotle and the Scholastics call Philosophia Prima, first philo 

 sophy, or general metaphysics. Such, for example, are the notions of 

 thing, being, essence, existence, negation, distinction, change, potenti 

 ality, actuality, accident, substance, cause, etc. These notions can 

 not be defined, properly speaking ; though they may be explained, 

 and the mind thus aided to distinguish and compare them. The 

 self-evident judgments which formulate mental relations based 

 upon them are, in the stricter sense, &quot;first principles &quot; ; and in 

 the strictest sense of all we describe as &quot;first&quot; those best 

 known principles of contradiction, identity, and excluded middle, 

 which, in the domain of logic, are seen to be regulative laws to 

 which all demonstrative reasoning and all consistent thinking 

 must conform, rather than principles which like those of the 

 special sciences enter themselves as premisses into our reason 

 ing processes. 



Thirdly, the premisses must give the cause of the conclusion. 

 Not only ought the knowledge of the premisses to produce the know 

 ledge of the conclusion in our minds, in our &quot; logical &quot; order that 

 is true of all reasoning, but the premisses, to be strictly demon 

 strative, ought to reveal to us the real, ontological cause of what 

 is announced in the conclusion: understanding &quot;cause&quot; in the 

 comprehensive sense in which it includes the formal, material, and 

 final causes, as well as the efficient cause. While Aristotle rightly 

 emphasized the importance of formal and final causes in science, 

 modern logicians lay stress on the role of the efficient cause (216- 

 18). The Aristotelean doctrine on causal demonstration is very 

 clearly expressed by Dr. Mellone as follows : 



&quot; Consider the premise if anything is M it is P . Regarded as a logical 

 proposition, in the formal sense, it states that the antecedent is the reason of 

 the consequent : looked at in reference to the real world, it states that M is the 

 cause of P ; it implies that we have discovered a law of causation in Nature, 

 and M is the cause in question. Now when the syllogism is changed from the 

 hypothetical to the categorical form, M becomes the middle term : 



Hypothetical Categorical 



If Anything is M it is /&amp;gt;, All M is P, 



S is M; S is M; 



.-.Sis P. .:S\s P. 



Hence Aristotle says TO /ieV yap alnov TO pto-ov (An. Post., II., ii., 2) : 

 the middle term expresses the cause . We may therefore say with Ueber- 

 weg (Logic, 101) : the worth of the syllogism as a form of knowledge depends 

 on the assumption that general laws of causation hold in nature, and may be 

 known ; and that syllogism has the greatest scientific value in which the 

 mediating concept (the middle term), by which we know the truth of the 



IS* 



