  Pascal's analysis of arguments that originate from hypotheses seems to have been borrowed from mathematics. He argued that there are three types of hypothesis. The negation of some hypotheses implies an absurd consequence, and they must therefore be true. The affirmation of others implies an absurdity, and these must be false. In a third category, if no absurd conclusion results from either the affirmation or negation of an hypothesis, one cannot draw any valid conclusion about its truth. Logically, different assumptions may “lead to the same conclusion, for everyone knows that truth is often concluded from falsehood” (Entretien: II, 90). When applied to experimental situations, it meant that one could get apparently confirming results from a poorly executed experiment or one that is based on a mistaken hypothesis. Accordingly, even the phenomenal success of the puy-de-Dôme experiment did not show conclusively that Pascal was correct about the vacuum. On the other hand, Pascal implicitly assumed that a negative experimental result would have disconfirmed the hypothesis that his experiment was designed to test because, by analogy with the claim that ‘absurd’ consequences disconfirm mathematical hypotheses, he failed to realize that scientific experiments test clusters of interconnected hypotheses rather than individual hypotheses. The Duhem-Quine thesis, as it is known today, shows that negative experimental results may be attributed to any of the many hypotheses that are assumed in observations or experiments, and that the certainty to which Pascal aspired cannot be realized even when experimental results are inconsistent with expectations.