It's just parsimony.
if so far it seems that the world has explanations then it's more parsimonious to assume that that's the way the world works until there's evidence of something without an explanation.
And the problem is that you can't have evidence of a world without explanations because that would require an explanation.
And what's more likely, that sometimes there isn't an explanation or that sometimes we can't find one? I think the latter is clearly more parsimonious again.
We have a world that makes sense and we can often make sense of it but sometimes can't. After all, sometimes it seems that there wasn't an explanation and then we later discover that there was all along and we just failed to find it previously.
It's the same reason that monism is more likely than dualism. If there's no evidence of two kinds of ultimate substances then why assume it? Assume there's one kind of thing unless there's any evidence to the contrary. And if there can't ever be any evidence to the contrary then stick with one because it's more parsimonious.
"Your final sentence seems to say that even events which don't seem to have a cause/explanation actually do have one"
Well, I'm just saying that even an acausal explanation is a cause in a wider sense. It's just acausal in a scientific sense. If X happens *because of* Y then why is the cause in a wider sense even if Y is a probabilistic cause rather than a stereotypical clockwork-style "deterministic" one.
" but it's too complicated for us to predict, so it might look like there's no explanation. In short, you are supporting the position that there are no causeless events, nor can there be. Is this right?"
That is another possibility. And it is actually the view that I hold. That determinism is actually true and what seems to be acausal from the perspective of science is just down to a failure in our understanding. Acausality is really pseudo-acausality just like rolling some dice is pseudo-randomness (because it's really down to physics rather than actual randomness).
I think it's far more likely that scientists are unable to find causes once we get down to the quantum level than it is the case that there actually are no causes.
And, again, I'm using "cause" in a wide sense. Because scientists like to redefine stuff so that their models can help them make sense of their experiments and theories about what they observe.
In the scientific sense I'm sure it is indeed the case that the quantum world is acausal. But here we're talking philosophy. Scientific indeterminism is perfectly compatible with philosophical determinism. Philosophical determinism says that there is only one actually possible future ... and scientific indeterminism just deals with observations and what is unable to be predicted.
Plus, there are arguments against scientific realism: