Well, acting without reason is unreasonable, for sure. But since I don't think knowledge is (mostly) hierarchical, I don't think chains of reasoning are the main part of how we arrive at preferences. To the extent that knowledge does have foundations, the foundations are beliefs, and they're built in no particular order, and survive by merit of seeming to chime with other beliefs, fitting together in a paradigm. That effect where they seem to chime is an impression, a hunch, which is a feeling.
What reasoning can do is tell you "these two beliefs definitely can't go together, because they're logically incompatible", and then you have to jettison one of them (or attack the argument), even if it feels like they both belong. Somewhat disconcerting.