Way too many people get way too analytical about actually taking action on things, particularly when it involves political answers. It's a bizarrely unnatural way of acting for humans, and yet for some reason those of us who study human action and decision making are some of the most prone to falling into it. The human condition, in a nutshell, is never knowing exactly what the hell is going on but caring about exercising control so that we can actually try to make progress (whatever that is) in our lives. We don't just follow instinct where it takes us, but we are also limited by our frail faculties.
OK now I'm waxing poetic, so I'll get to the point. The fourth bullet point in Ryan Murphy's four point summary of what he's learned from James Buchanan so far is: "Even if you don’t have unanimous consent because people are being difficult, it’s reasonable to still assume that rules agreed to by a large enough majority constitutes a Pareto improvement, because screw it."
It sounds flippant, but there's a lot of wisdom there. At some point you have to just act. We will never know anything completely. The question is never "is this right or is this wrong". The question is always "is doing this more likely to be right than not doing this, or is it more likely to be wrong than not doing this?". Too many people have talked themselves into a rationalist ethics that weights sins of commission more heavily than sins of omission.
I don't get the logic that pushes people into saying things like "but you don't know if the carbon tax is the right price, so how can you justify that - the government can't possibly know what's optimal". Of course it can't possibly know what's optimal. I don't really know of anyone that's made that claim. But that's not the question at hand. The question at hand is whether it's likely to turn out better if we take this action than if we don't take this action.
So many times in life we have to just say "because screw it". You learn what you can learn (and ideally you learn a lot about the world you life in ahead of time so that you can make good decisions on the fly), and you make your decision. This is not a world where we pile up all our actions at the end of our lives and only count those actions and whether they are good or bad. In that sort of world you can wait to act until all the evidence is in. But that's not the real world. This is a world where throughout our lives we change things by both taking actions and not taking actions.