matter of doubtful credit."[1] Aristotle accepted the popular Empedoclean doctrine of the four elements and the commonly received notions of gravity and levity. In opposition to the true view of Pythagoras he held to the popular belief that the earth was the centre of the universe. He rejected the 'vacuum' of the Atomists.
Aristotle is also greatly influenced by the common use of language. He uses words in their popular acceptation without making any attempt to circumscribe their meaning scientifically. Thus it is the 'nature' of light things to rise, and of heavy things to fall, light things seeking their kindred nature in the heavens, and heavy things their kindred nature in the earth. Popular distinctions are identified with objective truth.
Aristotle's frequent apriorism is reducible to the acceptance on his part of inaccurate popular distinctions and to inaccurate distinctions of his own making. Take, for example, his rejection of the indivisible atom. According to Aristotle, body to be body must be regarded as divisible, therefore the existence of atoms (i.e., small bodies) was impossible. The concept (i.e., body) from which he reasoned deductively (i.e., in a priori fashion) was inaccurate. Reasoning from the same concept, he concluded erroneously that it is impossible for all bodies to fall with equal velocities. The heart is in the centre of the body—Aristotle rushed to the conclusion that it is therefore the seat of sensation. What, then, was the function of the brain? It was supposed to counteract the heat of the heart. And so absurdity follows absurdity.
Aristotle frequently 'rushes to conclusions.' Man, horse, mule do not exhaust the class of bileless animals.[2] For example, the elephant is bileless. Moreover, man is not bileless. Lewes in his Aristotle gives further examples of rash generalisations.[3] There is one rash generalisation in particular which infects his whole philosophy. He concludes that all natural phenomena are interpretable in the light of final causes. Reasoning deductively
