5 ideas
When an option is unavailable, people unconsciously downgrade their preference for it so that what they can get comes to seem what they wanted. Because this adjustment is causal and non-autonomous rather than chosen, satisfaction of adapted preferences is not good evidence of welfare, and it differs from deliberate character planning, where one consciously shapes one's wants to fit one's options.
If preferences shape themselves to the feasible set, then a society that restricts options can generate contented citizens and score well on preference satisfaction without being just. Utilitarianism and social choice theory therefore cannot take preferences as given inputs; they must ask how those preferences were formed and discount the ones shaped by constraint.
Some mental and social states, such as sleep, spontaneity, forgetting, humility, belief, and the respect of others, arise only as side effects of actions aimed at something else. This rules out a whole class of goals as targets of instrumental rationality.
The case shows imperfect rationality: a person who cannot trust his later preferences can still act rationally now by removing options in advance. It is the benchmark against which by-product states are defined, since some states cannot be reached even by this kind of indirect self-binding.
Justifying democratic participation by its educational or character-building effects on citizens makes those benefits by-products that disappear once they become the stated aim. Participation yields those goods only when people take part to reach good decisions for their own sake, so a political system has to be justified by the quality of the decisions it produces, with self-development treated as an incidental gain.