That's kinda weird thing really. In science the probability for a given theory to be true is usually not very important. Usually you operate with the best guess that you have, or best guesses that you have. Until shit gets proven. You could argue that "probability" is name for this best guess, but scientific probability is mathematical term, that requires you are able to calculate some sort of numerical value for your probability. You usually can't do that to "most viable alternative". For science this is not a problem, because science only cares about "truth" and there are no time dead lines for finding it or necessary decisions that you have to make before 2030. Allocating probabilities would serve no purpose other than bias researchers.
In politics "probable" is fuzzier concept and often just a cop out. You can justify anything with that idea, but you have no responsibility afterwards (damn, we went to the 5% range after all, sorry!). And you don't need any kind of real sources, just authority or lack of imagination suits just fine.
When we wander into personal world views or some casual conversations, assigning probabilities become really good idea. But then it's often about who's authority you trust most, than what data you can actually consider.
And end of the day most people still gravitate towards either "extremely likely" or "incredibly unlikely" most of the time. You just use likelihood as a way to show that you actually considered that your statement might be false, but you don't actually consider it to be.
This psychological tendency for people to make up their minds, and then not change their minds is actually at the heart of the problem. These "critics" could not have mass following to their bullshit ideas without it. But currently lots of people fail to understand that just providing half decent criticism against an idea does not prove the opposing idea true. Because human beings are naturally bad at not making their minds.
