by the way i've renamed alplausism to just plausism. and the basic point of the eschumption is that evidence trumps logic:
logic is based on givens, some of which are rules as to whether things are contradictory, and one of which is the principle that contradictions are not allowed. logic is good when you don't or can't have evidence, because most of the time things which appear to be contradictory that are also supported by evidence turn out not to be contradictory. the eschumption is a single given which defines the concept of evidence and its validity.