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Sunday, July 31, 2011

The Modal Last Man

Of all the interesting things I learned at our Routleyfest ("Remembering Richard Sylvan") event last week, perhaps the most striking was about the history of deep ecology:

The famous last man thought experiment was first devised and proposed by Routley, in 1973.

This very dramatic experiment asks you to imagine that you are the last person on earth. No other people can or will ever be born. In the time you have remaining, alone, you decide it would be fun to go around cutting down all the trees. Just for the hell of it. Question: what, if anything, would be wrong about this?

In his talk on Wednesday, Roger Lamb presented Routley's answer to the question. There does not need to be a valuer -- a sentient being according something value -- in order for something to have value. At least, there does not need to be any actual valuer. In an attempt to split the difference between realist and subjectivist accounts, Routley suggests that as long as there is a valuer at some possible world, then things like trees have value. And this accounts for why it would be wrong to chop them down.

Now, it seems to me that this gets the intuition behind "the last man" experiment wrong. The idea is to isolate the trees from the projects of humankind. The point is that the trees have value completely independently of the people. So invoking people -- even people somewhere else, merely possible people -- concedes that the trees have no deeply intrinsic value. Therefore I propose instead (as a counterexample to Lamb's version of Routley's solution) the modal last man:

You are the last possible person. Every other possible world is empty of people; your world, the actual world, has only you left. Since synchronizing time across worlds is problematic, we simply posit that you are the only possible person. (And, as it happens, contingently so.) Admittedly, this is a strange picture of modal space. But it seems legitimate enough to entertain, for the purposes of the experiment.

And so, again, you the last modal man choose to spend the last time any possible person will ever live going around killing all the trees. Is it wrong?

It seems to me that, if you think the original last man's decision was wrong, then you should also think the modal last man is wrong. But then, there is not -- because there cannot be, ex hypothesi -- a valuer to confer on the trees any worth over and above their own intrinsic worth. So Routley's solution misses the point.

I wonder what Routley/Sylvan would have said. That there are valuers at other impossible worlds? Perhaps...but then we could iterate my response, to the ultramodal last man--you are the only person in any world, possible or not....

In any case, it was a thrill to find out that a man I already credit with so many advances in philosophy (he was the first true dialetheic set theorist, I think), is also the mind behind one of the most famous and striking ideas in environmental philosophy, too. In so many cases, Routley was the first.