In a previous thread I wrote:

beliefs that are more specific and detailed, having higher information content, are inherently less likely to be true — or conversely put, a belief that is so broad and general that it could not possibly be false accomplishes that by claiming nothing of substance at all, leaving no claims open to falsify — so such unlikely, high-information beliefs that, nevertheless, still have not been falsified, have withstood much more testing than those that put forward nothing to test — Pfhorrest

This notion of the information density of beliefs dovetails into another prominent principle of belief-formation: the principle of parsimony, commonly called Occam's Razor, after William of Occam who coined a well-known formulation of it. This principle states that if given multiple beliefs or theories or abstract models that all concord equally well with the evidence at hand, the simplest of them should be preferred. I agree with this principle in general, and find that it relates in more detail to what Thomas Kuhn described as the structure of scientific revolutions.

Kuhn's account was a sociological description of how he observed scientific revolutions to have actually occurred in practice, which he attributed to non-rational social and personal factors more than to adherence to any kind of rational principles. But I think it can be adapted into a more advanced version of the principle of parsimony and used as a normative epistemological rule for how science, and belief-formation more generally, should rightly be conducted.

Kuhn observed science to advance in phases. The process begins with what he called "pre-science" where there are no prevailing theoretical frameworks or approaches, or "paradigms", uniting the research efforts, but rather many different competing approaches. Then it proceeds into what he called "normal science" once such a paradigm has been established by the widespread success of some theory. And then, as new evidence that cannot successfully be incorporated into that paradigm builds up, a period of what he called "revolutionary science" occurs wherein once again many different approaches compete in the effort to reconcile all those anomalies together with all of the older evidence into a new paradigm, re-establishing a new period of normal science.

I think that this general process can be turned into a normative principle for belief-formation by formulating it in terms of parsimony, or in terms of how complex a theory needs to be to account for the evidence at hand; because the entire point of coming up with theories, abstract models to believe, is to have an easier, simpler representation of reality to work with than just the whole body of raw observational evidence thus far accumulated.

On my normative account, the period of pre-science is one in which no single theory has yet been devised that can account for all of the evidence at hand, and so there is no better, easier, simpler, more parsimonious way of describing all the evidence than many different theories used in a patchwork to account for each of the disjointed areas of evidence. Once a theory is devised that can account for all of that evidence, that then becomes the better, easier, simpler, more parsimonious way of describing it all, and so the patchwork of other theories are rationally, pragmatically discarded in favor of it. There may still be other theories that also account for all of that evidence, and so are equally unfalsified, but unless they are in turn even more parsimonious, there is no reason to use them instead, and pragmatic reason not to.

But as new evidence accumulates that cannot be reconciled with the existing paradigmatic theory, the best way to describe all the evidence at hand begins to grow again into an unwieldy patchwork of the main paradigmatic theory and all of the exceptions and special cases needed to be made and used to handle the anomalous evidence, until at some point that patchwork becomes so complex that other competing theories, previously rejected as less parsimonious than the paradigmatic one, are now more parsimonious than the old paradigm plus all of its exceptions, and it becomes rational to adopt the best of them instead of trying to cling to the old paradigm and its mess of special exceptions.