According to the "hypothetico-deductive model of justification"
which came to be an accepted element of the empiricist consensus, when
observation reveals that the predicted phenomenon occurs as predicted,
the law from which it is predicted is "confirmed," or "corroborated," when
observation reveals that phenomena do not occur as predicted, the law is
"refuted" or "falsified." Prior to any successful predictions, a theoretical
statement is purely "hypothetical." Only direct observation statements
may be regarded as "verified." Positivists came to accept that all hypotheses
are only "confirmed" by the evidence. Falsificationists emphasized
that attempts to refute the hypothesis have failed and spoke of the hypothesis
as "corroborated." After it has been confirmed by a wide range of
successful predictions, and in the absence of any falsifying failed predictions,
theoretical statements move from being of a purely "hypothetical" status
to being rationally justified and are often called "laws of nature." The
difference between a "law" and a "theoretical hypothesis" (or "conjecture")
is thus merely the degree of confirmation or corroboration.