> So attacking people for living a different way is obviously wrong. At the same time, if a lifestyle is based on bad ideas, it seems like a benefit to attack those ideas.

Yes. But the point is that it should be attacked because it is a bad idea, not because it is a different idea. There is no need for tolerance to be limitless in order to be considered tolerance, just as there is no need for democracy to accept the election of a dictator in order to be considered a democracy.

> I see nothing wrong with being intolerant of caste systems.

Sure. But that doesn't mean that you are intolerant, the same way that attempts to assassinate (democratically elected) Hitler were not anti-democratic. It is neither necessary nor helpful to define those terms in such a way that they are self-defeating, there is a useful concept there that can sensibly be labeled "tolerance" that encompasses only the non-self-defeating aspects of tolerance.

> ie. the caste system is based on beliefs about reincarnation which we now know to be false

I am not too familiar with it, but is it really something that we know to be false, or just something unfalsifiable and therefore epistemically irresponsible to accept, as most religious claims the world over are? Not that it makes any difference for the relevance of those beliefs, but it's usually better to avoid an unnecessary burden of proof ;-)

>I am not too familiar with it, but is it really something that we know to be false, or just something unfalsifiable and therefore epistemically irresponsible to accept, as most religious claims the world over are? Not that it makes any difference for the relevance of those beliefs,

But that's just the point, if reincarnation is a valid belief, then the caste system is valid as well. The two justify each other. The caste system posits that your social status (caste) in this life is a result of your actions in the previous life. It's based on the theory of reincarnation that you will be born again and your next life will be determined by your actions in this one.

Reincarnation is only 'unfalsifiable', because of the nihilistic version of tolerance. Under any fair standandard it's properly classified as wrong. There is no rational reason to believe that you switch bodies after death. No rational person should believe such things absent strong evidence. It is mere superstition. We should be able to say that. Superstitions and false beliefs can and do cause harm, as with reincarnation upholding the caste system.

I think it's this misplaced notions of tolerance (like saying it's merely unfalsifiable rather than calling it what it is - wrong - that allow bad ideas to persist. And let's be honest, to say that belief in reincarnation is as valid as scientific beliefs or beliefs based on reason is basically a nihilistic denial of truth.

> Reincarnation is only 'unfalsifiable', because of the nihilistic version of tolerance.

No, it is unfalsifiable because there is no way to prove it wrong even if it is wrong, that is the definition of unfalsifiability, and has absolutely nothing to do with tolerance.

> There is no rational reason to believe that you switch bodies after death. No rational person should believe such things absent strong evidence. We should be able to say that. Superstitions and false beliefs can and do cause harm, as with reincarnation upholding the caste system.

I agree with all of that. But none of that gets you to "and therefore, this is false". The position that it is false is equally unsupported by evidence, and hence that no rational person should believe it does apply to that claim as well.

> I think it's this misplaced notions of tolerance (like saying it's merely unfalsifiable rather than calling it what it is - wrong - that allow bad ideas to persist.

Except you don't know it to be wrong, and making that unsubstantiated claim unnecessarily puts you in a weaker position, because a believer will in many cases notice that your position is just as unsubstantiated as theirs and say things like "but your position also requires faith!", which is indeed correct, and thus allows them to defend their position against your argument.

The idea of reincarnation is not "merely unfalsifiable", it is unfalsifiable. It is irrational to believe unfalsifiable claims. When you try to argue that their position is wrong, you are taking on a burden of proof that you simply aren't responsible for and that you also cannot meet. You are essentially shifting the topic in their favour: The question is whether they know that reincarnation is real, and instead of showing that they don't know that, you shift the discussion to whether you know that reincarnation is not real. Whether you know that reincarnation is not real is completely irrelevant to the question at hand. They don't know what they are claiming to know, and that is why their position is irrational and not worth consideration.

If anything, the idea that you have to disprove all unsubstantiated, unfalsifiable bullshit before it should be considered irrational nonsense is what allows those ideas to persist, because it erects a barrier that is impossible to overcome. Showing that a claim is unsubstantiated and/or unfalsifiable should be enough to undermine the credibilitiy of any such claim.

> And let's be honest, to say that belief in reincarnation is as valid as scientific beliefs or beliefs based on reason is basically a nihilistic denial of truth.

And you know why? Because one requirement for a belief to be considered scientific is that is has to be falsifiable. Being unfalsifiable disqualifies any claim from being considered scientific.