Friday, May 2, 2025

Aquinas' argument for the immortality of the soul

Aquinas argues that because the human soul has a proper operation—abstract thought—that does not depend on the body, the soul would survive the destruction of the body.

I’ve never quite understood this argument. It seems to show that there could be a point to the soul surviving the destruction of the body, but that doesn’t show that it will.

It seems that by the same token one could say that because my fingers have an operation independent of my toes, my fingers would survive the destruction of the toes. But that need not be true. I could simultaneously have my toes and fingers crushed, and the fingers’ having an operation independent of the toes would do nothing to save them. In fact, in most cases, fingers perish at the same time as toes do. For in most, though not all, human lives, fingers perish when a person dies, and the toes do so as well. So the argument can’t be that strong.

Still, on reflection, there may be something we can learn from the fingers and toes analogy. We shouldn’t expect the fingers to perish simply as a metaphysical consequence of my toes perishing. By analogy, then, we shouldn’t expect the soul to perish simply as a metaphysical consequence of the body perishing. That’s not the immortality of the soul, but it’s some progress in that direction. After all, the main reason for thinking the soul to perish at death is precisely because one thinks this is a metaphysical consequence of the body perishing.

And I am not denying that there are good arguments for the immortality of the human soul. I think there may be an argument from proper operation that makes even more progress towards immortality, but I’ll leave that for another occasion. Moreover, I think the immortality of the human soul follows from the existence of God and the structure of human flourishing.

4 comments:

Lars said...

Could you not use that argument—that the soul has a proper operation (abstract thought) apart from the body and that, therefore, the soul will survive—to also argue that the soul has pre-existed the body? And that's exactly what Plato also argued. And, yet, only the possibility of pre-existence is established. So, too, is only the possibility for postmortem survival established.

Stephen said...

Is human flourishing compatible with the immortal soul when *eternal conscious punishment/eternal suffering* is added to the mix?

If you were personally convinced on scriptural grounds of the *mortality* of the soul (e.g. 'God alone possesses immortality' 'the soul is in the blood ' 'the soul that sins it shall die ') would you still think there's a place for philosophical arguments for its immortality'?

Daryl said...

Alex,
Besides the flourishing argument for the soul, do you think any other arguments work?

Alexander R Pruss said...

Stephen:

The assumption in the flourishing argument is something like this: every kind of living thing is such as to be capable of flourishing. That does not require that every individual actually flourish--just that flourishing is possible for it. But you are putting good pressure on the argument. I now wonder if it only shows that the soul is the kind of thing that can survive death.

As a general matter of fact, arguments for false views are often worth considering.

Daryl:

Gabriel Marcel argued something like this: once we realize what kind of a tragedy the complete destruction of a *person* is, a universe so indifferent to value that it allows persons to perish is one where we can't trust our moral intuitions, and hence moral skepticism follows. But, I take it, moral skepticism is false. So persons aren't completely destroyed.