NOVELTY, SEVERITY, AND HISTORY IN THE TESTING OF HYPOTHESES - THE CASE OF THE TOP-QUARK

It is sometimes held that facts confirm a hypothesis only if they were not used in the construction of that hypothesis. This requirement of ''use novelty'' introduces a historical aspect into the assessment of evidence claims. I examine a methodological principle invoked by physi cists in the experimental search for the top quark that bears a striki ng resemblance to this view. However, this principle is better underst ood, both historically and philosophically, in terms of the need to co nduct a severe test than in terms of use novelty. Nevertheless, a hist orical factor remains in the assessment of some evidence claims.