Chapter 4 endnote 39, from Lisa Feldman Barrett.
Some context is:
People believe interoception is “for” feeling because feelings are important to people, and scientists, as people, create causal hypotheses to explain what is important to them.
Scientists often create hypotheses that are causal. They say that some phenomenon X is "for" some purpose Y, as an explanation for Y, because Y is important to them.
For example, "affect is important, and interoception contributes to affect, therefore interoception must be 'for' affect." This is called a teleological explanation.