I am interested in the philosophy of science, and am something of a heretical Bayesian, and so these will affect my way of debating. The main issues that influence my discourse are:
In order to arrive at any piece of information, we all need to make assumptions based on perfectly no evidence:
Even in a field like mathematics which has no need of scientific evidence, we must first assume we have access to perfect reasoning machines.
When judging scientific evidence, we must make many assumptions, such that the world was not created last Thursday (discussing this hypothesis is illegal in France) or that God is not influencing our senses or readings whenever we run a scientific experiment.
Keep in mind that all of these are assumptions we make before we even see any data. Thus calling people who reject any such hypotheses unreasonable is purely arbitrary, and its only motivation is really the Darwinian evolution of ideas -- basically we think that what worked for thousands of years will also work tomorrow; this is reasonable, but can be dead wrong.
In addition to these, when confronted with scientific evidence, each person will need more or less evidence to come to believe what the evidence is indicating. For example take these two situations:
I tell you that I have a rigorous mathematical method that predicts with 95% accuracy the outcome of the next soccer game (and give you evidence for it). How much will you bid on the next game?
I tell you that I have Paul the Octopus (may God rest his octopussy soul) which is able to predict with 95% accuracy the outcome of the next soccer game (and give you evidence for it). How much will you bid on the next game?
I expect that the amount you bid in each case would be different, and that the only reason for this difference is your prior belief regarding how reasonable trusting Paul vs. trusting mathematics is. There is no right prior and therefore no right amount of evidence to demand to believe something -- this varies from person to person and I find this situation completely reasonable, though I would personally go so far as to call anyone who would reject a hypothesis given infinite data unreasonable.
Many times we assume that there is no incentive to do bad science, but being part of the field I do believe many times such incentive exists. Even without the incentive, a lot of bad science is done anyway. Because of this, I do not find unreasonable anyone who rejects a scientific study because of unrelated reasons; although without making such assumptions, the only way to learn new things is to be our own scientists. I strive for balance.
(I'm pretty sure that the Regress argument fits in somewhere around here, but am too tired to write something coherent. And also check out the articles on epistemology and truth.)
How this translates in practice:
Rather than striving to provide undeniable proof, I will strive to convince as many people as possible of whatever point I am trying to make; my effort will be focused on methods of convincing others of my opinion, rather than digging references and bringing convoluted proofs.
I will use the words think and believe a whole lot. That is because I don't believe that anything is absolute truth, only relative truth, and so in working to convince you I will not try to demand that you accept anything as truth.
Does it all boil down to Wikiality? No -- I am not saying that whatever most people believe is that which we each consider to be our personal "truth", I am saying that whatever most trustable people say we can consider to be our personal "truth". And this is what happens in reality.
No, I don't think there is a fundamental distinction between opinion and fact.
And finally, what is truth? Here I would provide exactly the same response Jesus did.
