F. GONSETH discussed the validity of KANT's (1724-1804) a priori, when viewed as an absolute and unquestionable beginning for philosophy. He did not accept that "the debate is closed even before starting" when it is admitted that a priori are the "sine qua non of all ARCHETYPE 39 knowledge and judgements" as they set the very forms under which experience must unavoidedly manifest to us"( 1955a, p. 6)
In fact "compare a priori with the results of experience ( of whatever kind) is simply compare them with themselves. Nothing can emerge of this, if not that they must be as they are"(lbid)
Indeed, the a priori is established by the observer ( supposedly being the infallible philosopher) within his own frame of references and we are led to the autopoietic critique of the ways we observe reality and of what observation amounts to in these bio-psychological terms.
In short, no a priori can establish an absolute starting block, being out of reach of falsifiable research of any kind.