One of the early medieval scholars to emphasize the use of Reason was Adelard of Bath (d. 1152). Mike Flynn read an amusing quote from him during our medieval science panel at Boskone two weeks ago, and it's worth quoting in full:
[from Adelard's Quaestiones naturales] “[T]he natural order does not exist confusedly and without rational arrangement, and human reason should be listened to concerning those things it treats of. But when it completely fails, then the matter should be referred to God. Therefore, since we have not yet completely lost the use of our minds, let us return to reason.”Now, what's funny about this quote (in addition to the way Mike delivered it--and it got a big laugh from the audience) is that it conveys that inimitable sense of British impatience with the obtuse that one so often sees (ironically) on display in the writings of Richard Dawkins and Christopher Hitchens. In fact, if you removed Adelard's reference to God quoted above, you could fool people into thinking the entire quote was something written by Dawkins in the past year or so.
The myth of the Middle Ages being an age of 'blind faith' however, continues to be...a matter of blind faith.