The fact that you can't know anything for sure, should not stop you from inquiring about and comparing the possibilities and likelihoods of different things to be correct.
I agree, it certainly doesn't. It just means that when I arrive at a conclusion, I keep this fundamental core belief, my only actual belief, in mind and don't hold the conclusion so tightly that it can't change in the face of more accurate evidence.
Thomas Kuhn's history of scientific revolutions maps the fact that science repeatedly rejects new worldviews due to biases until finally a dam wall breaks and a new paradigm comes through. I just don't want to be one of the people obstinantly holding back a new way of looking at things whose time has come... if that time comes.
Keeping an open mind is important and I agree that we should strive to do that. It's very important not to view things getting disproven as a personal failure or a failure at all, but as progress and enlighment.
It's also important to note that jumping on the bandwagon of new ideas is not always the reasonable thing to do. Rigorous research takes time and that's why sometimes it takes time for a paradigm to shift, but I think often (especially in modern times) it's not that scientists want to defend the status quo, they just require convincing evidence to accept a proposition and it takes time to gather that evidence through repeatable experiments and so on.
For instance, take the double-slit experiment. It didn't take a lot of time for it to lead to a paradigm shift, but people still needed to verify the data and to repeat the experiment.
It also needs to be pointed out that physics is one of those sciences where evidence is actually easier to measure and quantify which makes it less susceptible to problems with anti-progress predispositions while social sciences have a harder time with evidence, so opinions hold more sway and progress, consensus and agreement might be a bit more problematic.
You mention jumping on the bandwagon.
You might enjoy the following section of this book talking about the bandwagon effect in science. It partially answers the question you had about the speed of light not necessarily being a constant after all, in that it discusses the reason why it may have been presented as a constant.
https://books.google.com.au/books?id=f1BpAgAAQBAJ&pg=PT332&lpg=PT332&dq=intellectual+phase+locking&source=bl&ots=tCCuaVh02t&sig=4esByekk7S5wXlxqSS7R44fKOiU&hl=en&sa=X&sqi=2&ved=0ahUKEwiw_uCnq-nUAhXCvbwKHSyoBSsQ6AEIXzAJ#v=onepage&q=intellectual%20phase%20locking&f=false
Also, I'll be addressing the double slit experiemt in future posts in this series, as it's a great example of paradox in action.
Great, I'll keep an eye on that and make sure I won't miss it.
In my opinion, the double slit experiment is really a paradox only in the sense of our intuition and perception. As far as I understand it, it doesn't really involve an internal paradox, it's just a way to show what matter actually is and neither the fact that it's happening, not the math that we use to describe it are intrinsically paradoxical.
Of course, I'm looking forward to reading your take on it and I'm eager to learn what exact paradox you are referring to.
I like that you bring up that there are some sciences that are more quantify than others.
I use this 'i don't know anything for sure' attitude to remain open to possibilities that fall outside what science can currently measure at all.
Germ theory was once preposterous because we didn't have the instruments to measure them.
We can now measuere gamma, xray, infrared, ultraviolet. On a more gross level, dogs can hear things we can't hear.
Again, Carl Sagan's flatland rap is great at pointing out the challenges of being able to experience extradimensional realities.
To reference a comment you make elsewhere, perhaps the reason why unicorns and dragons exist in myths is because some humans have found technologies that allow their consciousness to go into multidimensional realities and come back and report what they have seen.
Just because these things don't exist within our physical reality doesn't rule out the possibility to me that they may exist in other dimensions... dimensions which may have no physicality in the sense that we experience it at all.
I think that should also be the correct scientific attitude and I my personal opinion based on my limited experience is that that's how a great deal of the scientists look at it.
In the end, there is nothing that can be demonstrated with absolute certainty, but the degree of certainty that you might expect from a particular theory should also be taken into account.
Preposterous is a judgment based on intuition. Intuition has a lot of value when hypothesizing, but it should be excluded from the evaluation of correctness.
The more important thing is that when it was proposed, it was not unreasonable to view it as unsubstantiated by evidence as the evidence was not in yet. Keeping in mind that looking at the theories that have survived scrutiny gives you strong selection and confirmation biases.
Look at it this way. When germ theory was initially proposed, there were let's say 9 other theories to explain the same phenomenons that have now been shown to contradict the evidence. But before the evidence was in, you wouldn't have had a good way to distinguish between the 10. So saying that all of them were not substantiated at that time is not at all unreasonable.
Of course, I'm speaking a bit hypothetically here as I'm not actually aware of the exact history of germ theory, I'm talking about the principle.
Additionally, it's always possible, especially if you go further back in history, for particular scientists or even whole scientific communities to have been reluctant to accept new evidence even when it was clearly contradictory to the then accepted theories. My personal opinion is that it is less likely today, but again it is more likely in some branches of science than in others.
Sure, we cannot rule out anything that is untestable, but the question here would be how reasonable would it be for us to base our views on such unfalsifiable claims? There are just too many things that are theoretically possible and if we have no way to peer into them reliably, should we postulate them as reasonable?
Humans might believe in myths because they had technologies to peer into some other reality, but keeping in mind the utter diversity and inconsistency of myth, is it reasonable to assume they did?