Premise 2 in my argument is blatantly obvious. I'm not stipulating some contrived conclusion, I'm just pointing out that clearly, determinism could be true without all of our beliefs being true. There's nothing about determinism that would imply that all of our beliefs are true. This is far easier to defend that any of the premises in Huemer's argument.

> if P is false, then you should refrain from believing it

But this is just false if ought implies can, because there are plenty of situations where you can't help but believe falsehoods (say, when you're being convincingly tricked).

No, the premise of the argument isn't "we should try to believe what's true", it's "we should only believe what's true". A determinist can maintain the former while rejecting the latter. In fact, I don't see why anyone would accept the latter. There are situations where it's impossible to believe only the truth (say, if you're being tricked or lied to in a convincing manner), so saying we have a moral obligation to believe only the truth is absurd (at least, if you accept that ought implies can).

But of course, more generally, a determinist won't accept that ought implies can if by "can" you mean that we have free will to do one thing or the other. But again, that's just obvious.

My point is, consider the following argument:

1. If the argument above is correct, then if determinism is true, all of our beliefs are true
2. But clearly, determinism can be true without all of our beliefs being true
3. Therefore, the argument above is not correct

1 is uncontroversial, 2 is obvious. Hence, there's something wrong with the original argument. Which is probably why it was rejected several times.

No determinist alive believes that determinism implies that all of our beliefs are true. Hence it's a useless argument.

Such a confused argument. The "can" in "ought implies can" is about ability, not free will. This guy's argument arrives at the conclusion that "if determinism is true, then all of our beliefs are true", and he still doesn't understand why it kept getting rejected?

It seems like the majority of people would accept closed individualism and would therefore have no use for this argument.

> For four decades and counting, scientists have failed to detect the dark matter particles in terrestrial laboratories

This is irrelevant because ΛCDM doesn't say that dark matter is made of particles. It could be, of course, and particle physicists would very much like that, but it's not a necessary assumption to explain our observations.

> We stop trying to make the data fit the theory

> change the theory

These two are the same thing. When scientists try to "make the data fit the theory", they are changing the theory, not the data. Obviously. Because the data is what it is.

You can... use the scientific method to figure out ethical questions? Are you sure? Let's see...

Observation: murder exists

Hypothesis: murder is wrong

This already violates the scientific method, because the hypothesis doesn't explain the observation in the first place. Murder being wrong doesn't explain why it exists. Let's try it another way.

Observation: people think murder is wrong

Hypothesis: murder is wrong

Now we're getting somewhere! Except, well, we already have scientific explanations for why people think murder is wrong (namely in the fields of evolutionary biology and sociology). This extra hypothesis seems to be a violation of Occam's razor. But let's say those other explanations are insufficient. What's the next step? Predictions, of course! Now, what predictions does the hypothesis "murder is wrong" make? Well... it doesn't seem to make any predictions. At most, one could argue that, if the hypothesis "murder is wrong" is going to be scientifically meaningful, it must make the prediction "we will be able to build a measurement device that measures the "wrongness" of murder". But of course, no one knows how to build that device. If not unscientific in principle, this hypothesis at the very least seems to be outside what current science can discover.

Do you disagree? Do you think the hypothesis "murder is wrong" makes any other testable (in principle or in practice) predictions?