Don't worry, I think you've explained why it is nonsensical perfectly.
Rationalism and Relativism are diametric opposites. While Rationalism holds that your reason is the most important method of gaining knowledge, Relativism holds that Reason is simply the sum total of your personal experiences, and therefore entirely subjective.
There really isn't much meaningful dialogue between the two philosophies as both have opposing core positions. That's why it doesn't sound effective to you!
I'll try to give you an example here as requested.... a much cited logical fallacy, argumentum ad ignorantiam.
The Creationist says "I know God exists and you can't prove He doesn't" and the Atheist says "I know God doesn't exist and you can't prove he does!".
Neither side can ever reach understanding. Really though this is exactly what the relativist says.... neither are right, both are simply using their own system of reason and are equally astounded that the other side can make such a ridiculous statement.
Beyond that, there's also a big, messy problem with Causal relationships in that they are completely and utterly culturally imbued - different cultures from across the world have very different cause/effect systems.... I wont be able to quote from it as its years since I read it, but a cornerstone book in Anthropology called "Magic, Witchcraft and Oracles among the Azande" by Evans Pritchard, is a very important insight into cultural inferences that render all thought bound to its own reasoning system.
To heavily summarise it....The Azande have a system of belief that interprets beneficial and negative actions as the work of witchcraft. So if a man is sitting on his veranda and the roof falls and kills him, then everyone knows it is the malicious work of a witch.
Naturally, the skeptical Rationalist will say..... the termites ate the wood, they'd been eating the wood for years and it was only a matter of time before it fell. It was simply chance that he was sitting there when it fell.
The Azande would reply that they know very well that it was the termites that ate the wood, but its the temporal relationship between the event and the man sitting there in which the witchcraft inhabits. They had been eating it for years, why did it fall in the relatively short time he was sitting there as opposed to all the other time when he wasn't?
In our system of belief we denote it as simple chance that the activities occured at the same time. Our system of thought has no better way to define this, we simply cannot express any greater depth of thought into it and assume, therefore, that it is itself a simple event unworthy of attention (a logical fallacy in itself).
So really, all we can actually state from this experience is that our system of reason does not have the capacity to delve into this area in which the Azande have a formulated and, to them, logical cause and effect relationship. We certainly can't use argumentum ad ignorantiam, our ignorance of any greater causal relationship is no evidence against its truth..... Surely then, we must bow to the Azande's greater insight?
Anyway, as I said from the start, by definition all that I have written here is a form of logical fallacy anyway. That's the beauty of these devices, they can be applied liberally when needed, especially with burdens of proof.... because sometimes you simply cannot prove something sufficiently to someone, even when it's readily obvious to you!
Worse, the very same fact can be presented by both sides and construed to mean the exact opposite. Which, if you go back to my first post in this thread, is why I said that instead of trying to convince others of your own veracity, it is more important to learn why other people interpret their facts the way they do, as this gives you a wider insight, than trying to insist upon a sole, inviolable truth.
