Of course Zen recognizes there are valid reasons to doubt sensation, perception, conception, etc. (e.g. illness, injury, wrong views, etc.), but it does insist on acknowledging the fact that there is no valid reason for accepting the purely hypothetical notion that reality is ‘other than’ it appears to be. It is intrinsically irrational to posit the existence of a reality we cannot experience; if such a reality existed it would, by definition, be inherently unverifiable. Recognizing unverifiable notions as they are – unverifiable – Zen recognizes them as not simply irrelevant but, in that they can only add unnecessary complications to our understanding, in the spirit of Ockham’s Razor, are contrary to sound reason.
Excerpt from, Zen Cosmology: Dogen’s Contribution to the Search for a New Worldview p.98