Complex sentence: Aside from the initial appeal to plausibility of desires that do not directly contribute to one's life going well, Parfit contrived situations where S is indirectly self-defeating--that is, it makes demands that it initially posits as irrational.
Split into simpler sentences: Aside from the initial appeal to plausibility of desires that do not directly contribute to one's life going well, Parfit contrived situations where S is indirectly self-defeating. That is, it makes demands that it initially posits as irrational.