Learn English – What word or phrase describes the quality of an assertion to be inbetween a fact and an opinion

I'm looking for a word or phrase that describes a statement that is neither a scientific fact nor an opinion. Google defines opinion as "a view or judgment formed about something, not necessarily based on fact or knowledge" but I'm looking for something that is based, at least indirectly, on knowledge.

For example, if I believe it is pointless to brush teeth in the morning since no food has been eaten since the previous night, what would this statement be called? I don't think it's a scientific fact since no studies or experiments have been made to prove it, but I don't think it would be called an opinion either, because it is at least logical. Would it be correct to call it a philosophy?

Another example I came across is as follows: one person was arguing that if a person (i.e. a hacker) was trying to guess the password to something, nothing is known about which order or which passwords they would try. Therefore, having minimum requirements for passwords is pointless (e.g. "8h4fhA" may seem like a more complex password than "apple", but technically there's no guarantee a hacker wouldn't test "8h4fhA" first). Would this be an opinion or fact or something else? While the premise seems true and the conclusion logically follows, I personally disagree; for example, it seems much more likely a person would guess "password" (or something easy) than "8h4fhA".

Another good example is deciding which car to buy. It's a matter of opinion which car is better than others but at the same time there are facts and reviews that can back up claims so it's not purely opinion.

A general example is when experts in an area disagree on a subject, for example if eating cheese before going to bed helps sleep. If one scientist claims that it does, should this be referred to as his opinion since there are other scientists and studies done that show that it does not?