The adoption of the hypothetico-deductive model of justification involves the frank abandonment of the goal of "proving" or "verifying" hypothetical laws by induction from particular instances. Instead the HD theorist advocates justifying the acceptance of scientific hypotheses on the basis of a high degree of confirmation by the observation statements which are themselves held to be "directly verified" by observation of the world. Much criticism from outside the empiricist consensus was aimed at this alleged incorrigible foundation of directly verified observation statements. But inside the consensus it was the problem of confirmation of the hypotheses built upon this foundation which tended to bedevil HD advocates.While the move away from "proof" in favor of the much weaker notion
of "confirmation" seems a reasonable strategy for empiricists in
the face of the intractable problem of induction raised first by
Hume, it turns out that even so the ghost of that old problem still comes back to
haunt the advocate of the H-D account of justification.
Out of the torturous and seemingly arcane debate over these problems two famous "paradoxes of confirmation" can be distilled:
The Grue Paradox