Officer Pupp examines a brick.
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Thomists generally accept the so-called “convertibility principle,” according to which being and goodness are one and the same thing. One way of explicating this doctrine is in terms of tendencies and dispositions: concrete objects have an innate tendency to persist in being,1 the satisfaction of innate tendencies is intrinsically good,2 and hence it is intrinsically good for a concrete object to persist in being.
It occurs to me that this view allows us to construct a natural law argument against the permissibility of suicide. According to standard natural law theory (NLT), it is always wrong to intentionally suppress or pervert an innate tendency or faculty. If we have an innate tendency to persist in being, then suicide becomes a clear case of deliberate tendency-suppression: we have a disposition towards persistence, the fulfillment of this disposition is intrinsically good for us, and the suicidal person is deliberately frustrating this disposition. If this is right, then it follows that suicide is always seriously immoral.3
It is worth noting that this is entirely compatible with the permissibility of refusing disproportionate or extraordinary end-of-life care. This is because declining unwanted care does not involve taking a positive act to inhibit the tendency to persist: rather, it is simply refraining from taking action to actualize the tendency. But failing to act in furtherance of a certain good is not the same as deliberately acting against that good. Just as NLT forbids contraception but permits natural family planning, so too will it prohibit suicide but allow for the refusal of disproportionate treatments.
This is essentially just bog-standard perfectionism about well-being. For a defense of a specifically-Thomistic variant of perfectionism, see Shea and Kintz (2022).
Some might object that given Christian theism, death doesn’t involve our ceasing to exist. However, this is not the traditional view among Thomists (including Aquinas himself): rather, the Thomistic position has traditionally been that human persons are animals, which cease to exist at their deaths, and then come back into existence at the resurrection. Our souls persist when we are dead, but we ourselves (being composites of body and soul) do not. For a good discussion of this topic, see Hewitt (2023).
But this seems to be a reductio to the view, implying that it would be wrong to commit suicide to avert infinite suffering, when one would already die one second later.