Iain Dale says:
Frankly, it doesn't really matter what we do in this country on global emissions if we can't persuade India and China to follow suit.
It doesn't follow, however, that it's irrational to curb our own emissions. To see why, consider Newcomb's problem.
Imagine two opaque boxes, A and B. A contains £1000. B contains either nothing or £1 million.
You have a choice. To take only box B, or to take both boxes.
Now, here's the wrinkle. A superbeing, with great powers of foresight, put £1m into box B if and only if he predicted you would choose only box B. If he predicted that you would choose both boxes, he put nothing in it.
So, do you take both boxes, or just B? There are two lines of reasoning.
1. "I'll take both. The £1m is either in the box now or it isn't. Nothing I can do will affect that. So I might as well take both boxes."
2. "I'll take only box B. The fact that I'm making this choice is evidence that the £1m is in the box. So the only chance I have of getting the £1m is to forego the £1000."
There is a parallel here with environmentalism. The case for curbing emissions in the UK alone is like the case for taking only box B. We hope that our choosing to do this is evidence that others - like the Chinese and Indians - will also choose this. This has nothing to do with the UK exercising "leadership" - that's drivel - it's that our choice to curb emissions is likely to be replicated by people who are in similar positions facing similar choices. Our choice is evidence for what others would choose.
Those who reject this, like Iain, are those who'd choose the two boxes.
There is, then, a clash of rationalities. In his best book, Robert Nozick called this the conflict between causal expected utility - the two box choice Iain is advocating - and evidential expected utility, the one-box environmentalist choice.
In fact, there's also a third rationality, which I suspect greens are using. It's symbolic rationality. Greens want to symbolize that they care about the environment and the future, even if their own actions make no material difference.
So, maybe the difference between Iain and the greens is about which rationality to use.
But here's the quirk. If we only ever use the causal rationality which Iain implicitly endorses, we would never vote - because our own individual vote would never make a difference. It's only evidential or symbolic rationality that justifies voting. We vote to either symbolize who we are, or because we hope that our decision to vote is evidence that like-minded people will make the same choice.
So, here's my challenge to Iain. Either show why causal rationality is more relevant to carbon emissions than evidential or symbolic rationality. Or don't vote, and don't call upon others to do so.