As soon as we (humans) start discussing reality, we encounter the fundamental problem that our discussion divides a unity. This problem has two aspects:
1, that we comprehend reality as both one and many units at the same time, and
2. that each of us distinguish him- or herself from reality;
the former meaning that reality is ambiguous for all of us, and the latter meaning that reality is contradictory for each of us (between all of us, ie, you is a part of reality but I’m not). These aspects mean that the discussion is fundamentally paradoxically contradictory, as also Bertrand Russell demonstrated with his paradox. This problem can also be expressed as that reality have to consist of units (objects) at the same time as that objects can’t be real, ie, that reality can’t be real. The problem we encounter is thus that the discussion itself contains a paradoxically contradictory core.
This is (I think) the reason why Ludwig Wittgenstein stated that: “Whereof one cannot speak, thereof one must be silent”, and why science is empirical. There simply isn’t any other way to distinguish knowledge from belief than by agreement between theory, ie, belief, and practice (in Swedish “science” is actually called “vetenskap”, where “veta” means “knowing”, so that “science” in Swedish is the art of distinguish knowing from believing per definition). Trying to find knowledge by discussion alone, ie, among empirically untestable statements, is bound to end up in Russell’s paradoxical contradiction, that is, what we must be silent about (to avoid the paradox’s infinite orthogonal carousel). Discussion can’t find knowledge other than by arriving to theories that can be empirically tested. In itself, it is just an infinite orthogonal carousel.
Unfortunately, explaining the paradoxically contradictory nature of discussion will never get rid of people that search the truth in discussion itself, because never will all people understand this explanation. Just as that not all people can understand math, not all people can neither understand this fact. The fact is thus like democracy, something we (scientists) have to fight for every day, with the difference that we in this case have to fight against those that think they have found the truth in discussion (ie, extremists like cladists and particle physicists). We have to fight for science itself against extremists, which isn’t easy, since science is inherently ambiguous, ie, that there are several equally true truths. The fight is thus that we consistently have to say that: no, the matter is more complicated than that, although we at the same time try to simplify matters as much as possible. We thus have to uphold the window between over-simplification and over-complication, ie, the window of science. Without it, we’re lost to the black-and-white approach, ie, if you’re not with us, then you’re against us.