Rational animal

Rational animal is a classical definition of man.^[1] Though it is often attributed to first appearing as a definition in Aristotle's Metaphysics, Aristotle does not define it here. In the Nicomachean Ethics I.13, Aristotle states that the human being has a rational principle.

The definition of man as a rational animal was common in scholastical philosophy.^[2] Catholic Encyclopedia states that this definition means that "in the system of classification and definition shown in the Arbor Porphyriana, man is a substance, corporeal, living, sentient, and rational".^[2]

Descartes

In Meditation II of Meditations on First Philosophy, Descartes arrives at his famous "I am, I exist" claim. He then goes on to wonder "What am I?" He considers and rejects, "rational animal":

Shall I say 'a rational animal'? No; for then I should have to inquire what an animal is, what rationality is, and in this one question would lead me down the slope to other harder ones.^[3]

Quotes

• Man is a rational animal who always loses his temper when called upon to act in accordance with the dictates of reason. – Oscar Wilde
• It has been said that man is a rational animal. All my life I have been searching for evidence which could support this. – Bertrand Russell

See also

• Genus-differentia definition

References

1. ^ http://plato.stanford.edu/entries/cognition-animal/
2. ^ ^{a b}  One or more of the preceding sentences incorporates text from a publication now in the public domain: Herbermann, Charles, ed (1913). "Man". Catholic Encyclopedia. Robert Appleton Company. 
3. ^ The Philosophical Writings of Descartes Volume II. Translated by John Cottingham, Robert Stoothoff, Dugald Murdoch. Cambridge University Press. 1984.