Abstract
Franklin and Pickering agree that scientists in an experimental sequence, like the one to be discussed here, choose to accept certain experiments and their results as crucial, but disagree as to whether such choice can be justified in terms of an on-line estimate of evidential reliability. This paper suggests that it is possible to define a position between Franklin 's Bayesian objectivism and Pickering's social constructivism. This position depends on considering the sequence of improvement in material technique and instrumentation as more important than any measure of reliability determined merely from such factors as evidential spread in relevant sequences, a factor that neither Franklin nor Pickering takes sufficiently into account