"It's only a decision in the sense that each day I "decide" not to go to medical school"
Well, it is a decision in that sense. That's a real sense in which a decision can be made. At each point in time we choose to do one thing from among the infinite possibilities available to us. And in making the decision to do that one thing, we are making the decision not to do any of the other things, even if not consciously.
I don't know where you're coming from with the "inaction is always our default position" thing. What do you mean when do you say "default"? Do you mean that we should (oof, I hate to bring "should" into this) sometimes maintain the status quo even if doing so doesn't have the highest expected outcome for us? Do you mean that we should sometimes maintain the default even if the expected outcome of doing so is dramatically lower than doing something? (I'm gonna go ahead and assume that this isn't what you believe, but if it is, our argument has to end here, because the only response that I've got is, "Well, that's really stupid.")
Because I would argue that that's the situation that we're in with global warming. I actually agree with you that the scientific establishment should be treated with substantial skepticism. But I also think that global warming is probably happening, and through applications of logic I've decided that reacting to a fictional global warming is SO SO much better than not reacting to a real global warming that we'd be insane to choose inaction as long as there's still some non-infinitesimal probability that global warming's happening.
You seem to think that you have an ace in the hole with your argument that our society supports an "innocent until proven guilty" approach. In fact, I am both a believer in the "expected value" approach to choosing a course of action and an ardent defender of innocent-until-proven-guilty. This is because the downside of convicting an innocent person is dramatically larger than the downside of letting a guilty man free -- not only because locking up an innocent guy for 40 years is much worse than letting some embezzler get away with it, but because every time our legal system sends an innocent person to jail the public loses some faith in it, and faith in the legal system is one of the most fundamental elements of a stable and happy society.
Okay, I think I'm done. I'm pretty damn sleep deprived at the moment, though, so if I missed anything please point it out and I'll address it later.
*Not a criticism.