Routledge Encyclopedia of Philosophy

Immortality in ancient philosophy

New article December 10, 2002

1 Before Plato
2 Plato
3 Aristotle
4 After Aristotle


3 Aristotle

Aristotle did not take up the Platonic project of proving the soul’s immortality or of providing eternal rewards for virtuous conduct. Indeed, by defining the soul as the ‘first actuality of an organic living body’ (On the Soul II 1), he seems to have precluded the possibility that any soul can survive the dissolution of the body whose actuality it is. Two lines of thought complicate this story and seem to make room for some immortal element in the soul. The first is the caveat, stated twice (On the Soul I 1, II 1), that the continued existence of any part of the soul in separation from the body is impossible, unless there is some activity of the soul that is not a complex activity of the soul and body: thinking is explicitly offered as a possible example of this, in contrast to such activities as feeling fear or anger, which clearly involve psycho-physical cooperation. The second and related complication is that in his analysis of intellect and intellectual thought (On the Soul III 4–5), Aristotle refers to a mind that is ‘immortal and eternal’ and is somehow involved in human thought. If we connect these two strands together, we may conclude that we have found something like the rational part of an individual human being’s soul and that we are being assured of its immortality. However, another line of interpretation will make this immortal and eternal mind (what later tradition calls the ‘active intellect’) a force external to the individual, whether a divinity that may be personal in its own right or a reservoir of impersonal thinking power. On views of this sort, what Aristotle is offering us falls far short of anything that might be considered personal survival (see Aristotle §§16, 19).

Nor does Aristotle make use of the arguments we found in Plato that a certain form of life is to be preferred because of its consequences in the hereafter. It is true that he argues for the superiority of the life of philosophical contemplation on the grounds that the philosopher will most resemble the gods, be dearest to them and be most likely to earn their favour (Nicomachean Ethics X 8). But these benefits belong to this life, not the next. So too when his advocacy of contemplation culminates in the call to ‘be immortal, to the extent possible’ by employing our reason, the divine element in us (Nicomachean Ethics X 7). There is nothing about the afterlife in this appeal, only a striking shift of meaning. Immortality has here come unmoored from survival after death or eternal existence and now simply denotes a kind of activity that a participant may share in for finite, even fleeting, periods of time.

On the other hand, Aristotle’s commitment to the literal immortality of the gods is unequivocal (see Aristotle §16). The heavens and earth are eternal in past and future, and the eternal movements of the heavens are the result of the eternal activity of gods who keep them in motion (Physics VIII 6; Metaphysics XII 7–8; On the Heavens I 3)

How to cite this article:
BRENNAN, TAD (2002). Immortality in ancient philosophy. In E. Craig (Ed.), Routledge Encyclopedia of Philosophy. London: Routledge. Retrieved January 16, 2022, from

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