@The Pentacle Queen,
Let me do some mental scribbling: I prefer to "reason" "a reasonable or satisfying answer" to a problem. Problems are usually stated with a sufficient ambiguity to make them "open ended" (I'm not thinking of formal problems as in logic or some mathematics). We may pose a problem that may be no more than an introduction to an evolving problem. As such--and I'm thinking out loud here--a solution or answer may be neither exhaustive nor exclusivee (not an omnicompetent reason or final word). In that sense there might be more than one reason. Now, by that I mean more than one useful answer to a question, not more than one cause for an effect. I see many so-called effects as being "overdetermined", i.e., the result of a complex set of antecedent (necessary and sufficient) conditions.
And we mustn't forget the likelihood that some problem posing and solving includes an unconscious component.
What did Pascal say?: "The heart has its reasons, of which reason is ignorant".
For philosophy Nietzsche claims that "Philosophy is the dressing up in rational argument of moral beliefs, intuitions and desires."
Bradley said that "Metaphysics is the finding of bad reasons for what we believe upon instinct."