The best explanation is not necessarily the
truth, though sometimes a best
explanation might be so good that we say it describes what truly
happened. This is a colloquial use of “truth”, different from the
kinds of technical, universal assessments we use in formal logic.
Best explanations are modest. They allow for the possibility that another explanation might eventually supplant our preferred explanation, should new information be found, or should circumstances change. Twice two will always be four, but the current prime minister of New Zealand might not always be male. With respect to reasoning, not all truths are equal.
Here we will not limit ourselves to binary assessments, such as “true” or “false”. Preferring talk of “best explanations” allows for shades of better, not-so-good, unlikely, and so forth. This opens up the possibilities of both exercising judgements and adjusting conclusions as further evidence arises. “True” connotes “unchanging”, but we want our system to capture the dynamics of investigations, plus the simple fact that with the introduction of new evidence we often change our minds. In short, a system open to change is best built on a vocabulary that doesn’t suggest answers that transcend time and context.