Excerpted from chronicle.com:
The reasons by which we make our behavior coherent to ourselves changes together with our view of who has reasons coming to them.
It says "the reasons changes", is it a typo of "the reasons change"?
It's most definitely an error. Good catch. I have to add that, even with the grammar corrected, I find the entire sentence incomprehensible. But - I haven't looked at it in context.
IMO, this is not so much a typo as a grammar flub - one sadly common among native speakers.
The writer has matched the verb form to the closest noun, "behavior", rather than to the subject, "reasons".