Bombs and coconuts, or rational irrationality

Abstract

The claim that it is rational to act against one’s own interests if doing so follows from an advantageous disposition rests on a revision of the Self-interest Theory, where rationality is situated in dispositions rather than individual acts. In this framework, an act is considered rational if it results from a disposition that is expectably-best for the agent to possess. However, this account falters in scenarios where a disposition, once beneficial, becomes transparently self-destructive or suboptimal. Thought experiments involving threat-ignoring behaviors and temporary insanity illustrate that while it may be rational to acquire a specific disposition, it can be simultaneously irrational to act upon it when the resulting costs are known to be disastrous. Furthermore, the argument that believing in this dispositional account is practically beneficial does not demonstrate the theory’s truth. There is a fundamental distinction between practical reasons for adopting a belief and epistemic reasons for its validity; a useful belief remains false if it contradicts the basic requirement that rational agents should not intentionally frustrate their own aims. Ultimately, the rationality of acquiring a disposition does not entail the rationality of its subsequent acts. – AI-generated abstract.