You may ask, what do I mean by this? expecting a reasonable answer from me, when the idea I'm presenting is concerned with reason being not entirely "reasonable".
I was thinking along the lines of reason being in the eye of the beholder. For example, suppose I reason things through perfectly and conclude that I should kill myself? (sorry to sound harsh, but just for the sake of this conversation).
I suppose I'm also concerned with morality, in that not all things can be reasoned through, and therefore not all things that must be done are reasonable. If not all things that are neccesary are reasonable, then reason isn't always neccesary. (Here I am trying to provide a reasonable argument against reason, when I don't think it's possible)
I do think that an unreasonable argument can be made against reason, and that it can be necessary, it may not make sense, but thats the point, it can't if it's trying to argue against reason.