"Not knowing", or changing one's mind.

[ReneZ]

History is not an exact science in the sense of chemistry or computing the ballistics or whatever you call it of satellites (sorry, Rene).

I have no problem with that

In fact, I think it is important to be able to accept that something is 'not known'. At least 'at the present time' and based on the available evidence.  That also happens all the time in the so-called exact sciences.

While it may seem unsatisfactory not to be able to answer something, this may simply be the reality. The way forward is either to find more evidence, or accept that there is no way out of the situation.

It is tempting to just 'decide' one way or the other what one prefers. This helps to get out of the unpleasant situation of not knowing. However, then one has to be able to change one's opinion whenever new or better information arises.

The capability to reject one's own ideas when better ones arrive is what matters.

This may be easier in exact sciences than in the humanities, because usually the evidence is much stronger and much more quantitative, and the mindset is therefore a different one. It is expected to happen a lot.
Entrenching oneself with one's hypothesis against unpleasant evidence, and tactics like sweeping it under the carpet or discrediting their source are just not going to work for very long.