> Any species that develops a civilization capable of space travel must necessarily have evolved a strong cooperative spirit, and so is more unlikely to exercise homicide as a first resort.

It's more accurate to say that HUMANITY would need a cooperative spirit in order to reach interstellar travel. I don't think it's accurate to assume that every species would need this.

And, beyond that, TDF addresses this through the assertion that humanity, at multiple turns, didn't want to partake in this Dark Forest ideology; we wanted to make peace and friends, but the other more advanced civilizations weren't having it. So even if they had a cooperative spirit in the past, that doesn't preclude that the spirit sticks around when the destruction of your species is at stake.

> If Dark Forest were true, and there was a murderous civilization that wanted to kill every other, we would all be dead already. You can make an entire galaxy's worth of relativistic kill missiles with the mass of a medium size asteroid.

That's being awfully presumptive.

Constructing even a galaxy's worth of kill missiles and launching them wildly like a shotgun isn't a strategy that any logical civilization would do. They'd end up destroying tons of empty planets that could have rich resource deposits or be habitable for future colonies, and they'd know that. Maybe there are illogical interstellar civilizations, but it stands to reason that they'd be More Rare than Logical ones, given it takes some form of logic to even accomplish space travel.

Targeted strikes make more sense. So you have to have a Target. Humanity has been broadcasting RF for about 100 years. The milky way is 105,000 light years across; at best we're detectable by 0.095% of just our own galaxy. Maybe we haven't gotten one of these kill missiles because they haven't heard us yet. Or it's on its way.

But all this requires life to common; the dark forest theory asserts that the reason life seems rare is because its common and everyone is just being quiet, but the other possibility is that life is, well, rare, and that's probably more likely. If life is rare, then the dark forest theory kinda goes out the window because the novelty of finding new life would invariably overwhelm a hypothetical risk that your species has never encountered before.

IMO space contact & travel will have one of three outcomes. (1) The light speed limit can be worked around and none of this matters. (2) Life is Common, and the Dark Forest Theory is valid between species. (3) Life is Rare, humanity will colonize the stars, but a version of the Dark Forest Theory will begin to apply between human colonies separated by hundreds of lightyears. If its been 150 years since anyone in your colony has ever talked to Earth, then you're not really a colony anymore, but it's obvious to you that Earth won't see it that way. Your colony creates other colonies, and it takes earth hundreds of years to find out about them, if you decide to even tell them (because what do you owe earth?). So a thousand years pass and we've got dozens/hundreds of Tribes of humans who can't really talk to each other, most of whom don't even know of each other's existence, all developing culture, science, and weapons at independent rates. Really starts to look Dark Forest-esque, doesn't it?