but it's not a matter of what we believe ought be so vs ought not be so -- that is, it's not a matter of what we want to be true. It's a matter of the strength

but it's not a matter of what we believe ought be so vs ought not be so -- that is, it's not a matter of what we want to be true. It's a matter of the strength of evidence we ought to have in order to draw conclusions, given other sets of evidence. It's a normative position, but it's not the specific normative position (based on confirmation bias) you described above. Think of it as a spectrum. On one end is the pure flake -- always giving too much weight to the newest evidence, no matter how weak, and therefore swinging wildly between different beliefs (I've heard this called "regressive bias"). On the other end is the pure dogmatist -- always giving too much weight to prior evidence, and therefore holding fast to a prior conclusion, ignoring or dismissing even strong contrary evidence ("confirmation bias"). Somewhere in the middle is the proper level of evidential weighting -- giving both old and new evidence the appropriate level of consideration, and therefore changing beliefs exactly as much as is warranted.