In today's epistemic context, questioning the legitimacy of the scientific propositions we produce and teach can often seem an audacious endeavour, and this, despite the fact that a rich western tradition, from Morin to Protagoras and through Vico, Bachelard and Piaget forewarns of the illusion of a universal, divine knowledge. The "end of certitudes", the rooting of knowledge and the inquiry into the wishful based on the feasable are all principles which enable us to ground the knowledge-legitimating work we elaborate; and they represent an alternative to the dominant epistemology.