We ought to do something about climate change. One reason for thinking this is that if we continue the way we’re going, we will make future generations much worse off, and so we owe it to them to e.g. enact policies that will dramatically reduce greenhouse gas emissions. But such policies would have all sorts of other effects. Factories would be moved, rebuilt, or shut down. People would find jobs as regulators, inspectors, and lobbyists that they wouldn’t have otherwise. People would drive different cars, get different degrees, and buy different products. And all of these things would affect decisions about when, where, and with whom to procreate.
This generates a puzzle (the Nonidentity Problem). To see why, let’s zoom in a bit. Suppose that, if we do not implement new emissions policies, Baby X will be born to a couple in Sacramento a year from now. However, if we do adopt new policies, the couple will instead move to Washington, D.C. for new jobs with the EPA. They’ll agree to wait a few years to settle into these new jobs before having children, and they will have a different child, Baby Y, in 2023.
If we do not adopt the new emissions policies, who will be made worse off? Baby Y will not be made worse off, since Baby Y will never exist. The couple will raise Baby X as an only child in Sacramento, and Baby Y will never be around to suffer whatever consequences result from continued emissions at current levels. Nor will Baby X be made worse off by not adopting emissions restrictions, since, if we did adopt them, Baby X would never exist. On the (perhaps optimistic) assumption that Baby X’s life will not be so bad as to be worse than never existing at all, Baby X will be no worse off under our current policies than under the new ones.
The point generalizes. There are the people, the Xs, who will exist if we do not clean up our act, and the people, the Ys, who will exist if we do. Given the fragility of the circumstances under which a particular person is conceived, they are mostly not the same people. So, whom do we make worse off if we refuse to change our current policies? Not the Xs, since they will only exist if we maintain the status quo. And not the Ys, since they will never exist to suffer the consequences of our refusal to change.
We ought to do something about climate change. Maybe we even owe it to future generations to do something. But not because they will be worse off if we don’t. So, why?