I think even Little Paul is off on his points, though better than IA. Though it maybe that my view of Relativism is skewed too much from what IA and LP think of as Relativism.
Relativism does need a healthy dose of Scientific Method and Rationality to become a useful point of view, as then you need to test your beliefs and the things you hold as truth. IA is wrong in that Relativism demands that all beliefs are true because people believe them and thus can be disproved by disproving such a belief, which in itself is consistent with the base position of Relativism, but will fail once Scientific Method and Rationality is applied.
Relativism holds that people with different frames of reference created from different life experiences will view events in different ways and thus interpret them different and will then come up with a different version of the truth. This is the same for human interactions, 'morals' and society norms and it is in these slightly areas less defined by the cold logic of numbers that Relativism has it's greatest power. In science or views of the natural world then all view points will tend towards a actual 'Truth' as more evidence is presented and more phenomena is understood, assuming people apply some form of Scientific Method and Rationality to their view points and are willing to admit when their view point is wrong and re-construct their version of the world.
The interesting thing is that neither of IA's examples actually disprove Relativism, but show the strength of it (even if in a weird way.)
>>Logically:
Both person x and y could assent to competing theories that contradict one another, and relativism necessitates that both theories are true. However, this leads to a contradiction. As person(x) assents to model(p) and person(y) assents to model(q), relativism concludes that both p and not p are true. Therefore, relativism leads to a contradiction and is therefore logically inconsistent.<<
Relativism does not say that both are True, but that Person X believes that Model(p) is true and Person Y believes Model(q). Now if this was a scientific model then as long as X & Y were true scientists then they would have proof for their model and arguments for their model and against the competing model, thus they will continue to find evidence, apply it to their model, re-evaluate and use the evidence to argue for their models, and try to convince the other to their model. Also being Good Scientists they will then come up with experiments that will definitely prove or disprove their model and/or the competing model, and thus once the experiment(s) are completed we will have a better idea of what is true.
If X & Y did not have competing ideas that they both believed to be true (and thus the opposite to be false) then they would have less drive to prove their point, and it is possible we lose valuable knowledge.
If X & Y were not good scientists then this could lead to on-going arguments, but then they could (if they are convincing enough) convince other people to their sides, and as their groups grow so does the possibility of people joining who will be able to apply the Scientific Method and Rationality to the models and discover which is more true than the other.
If it is not a scientific issue, and thus possibly has no definite Truth then Relativism is the only thing that holds true, that your own life experiences are what allows you to interpret your surrounding world and construct personal models of how to interact with it. Then you could have two competing models which have no way to say if one is True and one is False, and we get closer to your paradox of two opposite ideas being true, but once again only one model will be true for any single person (assuming they have a reasonably rational mind.) The paradox is then resolved by pointing out that there is no real truth when it comes to human interactions, especially if you believe in Free Will. However if you believe in Determinism then that allows there to be a specific Truth and thus one is able to test against it, and once more Rationality and Science come to the rescue.
However in the 'Humans have Free-will' model then one must rely on Rationality to determine the best model for you and, if required, to convince others to your model.
>>Experience:
According to relativism, if person x is assents to the belief he can fly without the aid of aerial technology, then it is implied that he can. However, if he attempted to jump off of a cliff to prove his ability to fly, then he would fall rather than fly. As such, at the very least, our choice of belief is not necessarily consistent with experience. And if there is a relativist here who wishes to challenge my prediction, I invite you to jump off a cliff of the Grand Canyon with a number of us to witness it.<<
In the case of Experience, the Scientific Method helps here in that by providing experiments we will easily discover that Human's cannot fly, even if one really really believes they can. So Experience doesn't disprove anything, it just refines our model to be closer to the Truth, or at least towards a Truth we believe in enough to think that the evidence points towards, which is where Rationality and Science will help us by providing tools for us to use upon our own beliefs so that we are not deceiving ourselves. Relativism is our best hope towards us finding these things out for ourselves.
"Sticks and stones may break my bones, but i am Jesus"
"Nothing is worse than a fully prepared fool"