Swamp menace threatens omnipotent god

Tue 04 Aug 2009 12:09 PM

I have always thought that the Swampman thought experiment is analytic philosophy at its worst. I recently came up with a variant of it that might steal the title.

Explaining the idea requires that I explain the original Swampman and whinge a bit about how terrible it is. So, details below the fold.


John Heil provides a summary of the scenario:

In a much-discussed thought experiment, Donald Davidson imagines that, while wandering through a swamp, he is struck by a bolt of lightning and vaporized. Simultaneously, another bolt strikes a nearby tree stump rearranging the particles that make it up to produce, wholly by chance, a molecule-for-molecule duplicate of Davidson: Swampman.
Heil offers his own preferred interpretation of the case:
It seems natural to say that Swampman has Davidson's thoughts, beliefs, and preferences. Swampman differs from Davidson, not in what he wants and believes, but in the truth value of many of his beliefs. Swampman falsely believes he was a student of Quine's [etc.]
Yet, as Heil notes, there is another interpretation. Externalists about content would insist that ordinary people can think about Quine because their word "Quine" is casaully connected to the man Quine. For Davidson, "Quine" is the name he used to refer to his teacher. For us, "Quine" is a name in circulation in our community that is historically connected to that guy. Swampman can make the same sounds we make when we say "Quine", but it has no causal connection to the man Quine. So Swampman's lip flapping doesn't mean Quine any more than wind through a canyon that sounds like "Quine" does. For comparable reasons, Swampman's brain configuring itself in an arrangement cannot count as thinking of Quine - even if that very configuration in Davidson's brain would count as Davidson's thinking of Quine.

Heil thinks that this is the downfall of externalism. Obviously Swampman can think of Quine! Heil writes:

I like to think of Swampman as a counter-example to externalism: if, on externalist grounds, we would be obliged to deny that Swampman has endless thoughts, externalism is mistaken.
Contra Heil, I am inclined toward externalism. As such, I am willing to accept the externalist story about Swampman. However, I certainly don't think that we should be externalists because of the Swampman scenario.

The scenario is a terrible mess. Upon hearing the story, most people naturally think there is some connection between the Davidson body that is vaporized and the Swampman body which appears across the swamp at the same instant. The blue light and the smell of ozone make it just as if a Star Trek transporter had moved him across the swamp. Yet it is crucial to the case that Swampman accrete from muck "wholly by chance."

Here is what happens in the transporter scenario: Some widget records the micromolecular detail of Davidson's body and then destroys it. It then builds an identical body elsewhere. One may still worry that the duplicate is not Davidson; arguably, Davidson is killed in the process and replaced with a doppleganger. But remember that the scenario is meant to show something about intentionality, not about personal identity. If Davidson had studied with Picasso (rather than Quine), the duplicate would say "Picasso" (rather than "Quine") when asked who his teacher was. In short, the linguistic performances of the duplicate causally depend on things that Davidson encountered in his life. So, too, for the brain states of the duplicate. So, even if the duplicate would not actually be Davidson, its thoughts would have the same contents Davidson's thoughts would have had.

This point about a duplicate is all consistent with externalism. So, to do the work that the example is meant to do, Swampman cannot be a duplicate of Davidson. It must really be a randomly assembled heap of meat that, just by chance, matches Davidson molecule for molecule.

I do not have any intuitions about what the world would be like if things like Swampman really did self assemble from mud. I suspect that noone really has clear intuitions about it either. It is not something likely happen by chance, even in the whole history of the universe, so our intuitions are utterly out of their ken.

Could God make a Swampman?

To twist things around a bit, now ask whether an omnipotent God could produce a Swampman duplicate of Davidson.

Suppose it happens this way: God looks down as Davidson is vaporized, and He is saddened by this turn of events. He decides to make a molecule-for-molecule duplicate of Davidson, so as to set things right. Rather than creating the duplicate ex nihilo, God assembles it from atoms already circulating in the muck of the swamp.

Call the product of this scenario Fiat Swampman. A little reflection will reveal that the states of Fiat Swampman causally depend on Davidson's causal history. If Davidson had just cut his hair, for example, then God will make Fiat Swampman with short hair; if Davidson had just stubbed his toe, God will make Fiat Swampman with an achy toe; and if Davidson had studied with Picasso rather than Quine, then God would make Fiat Swampman so as to say "Picasso" when asked who his teacher was. In short, the story of Fiat Swampman is just a divinely-mediated transporter scenario. Since a transporter duplicate isn't a Swampman, in the sense relevant to the philosophical argument, then God would have failed to make a Swampman.

God is omnipotent, so he does not fail. Suppose instead that it happens this way: God sees Davidson vaporized and is saddened. He instantly creates an infinite number of swamp planets. I am supposing here that God can will for there to be stochastic processes, the outcome of which He does not will directly. So God watches the random happenings on each of the planets. On most of them, the swamp just sits there swamping. On some of them, a minor random thing happens - like a mushroom growing in the shape of Abe Vigoda. On some of them, even wilder things happen. There are infinitely many swamp planets, so for every physically possible event there is a swamp where that event occurs. God quickly sorts through them and finds one where a molecular duplicate of Davidson accretes out of muck. God takes this Swampman and sets him down next to a tree, just at the moment Davidson is vaporized. (God destroys all of the swamp planets when he is done; when you are omnipotent, you don't need to worry about going over budget.)

Call this scenario Sorting Swampman. If we imagine Sorting Swampman alone on his swamp planet, before God selects it, then it is clearly like the Swampman in the original scenario. It is formed by a random process of muck accretion.

Yet the Sorting Swampman who appears nearby Davidson is not merely a product of random accretion. It is a product of a larger process which includes lots of random accretion but also includes careful selection. Since God looked through all of the infinitely many swamp planets to find Sorting Swampman, He decided that the thing there would be a molecular duplicate of Davidson as surely as if He had assembled the body himself. God picks a body that utters "Quine" when asked who its teacher was just because that is what Davidson would say. If Davidson had studied with Picasso, then God would have picked a body that would utter "Picasso."

It may seem odd to say that the states of Sorting Swampman causally depend on Davidson's, but it meets the usual counterfactual and intervention dependence test for causation. Sorting Swampman is just a transporter scenario instantiated in a really bizarre mechanism. Any seeming oddness results from the fact that we never do encounter mechanisms like this, so our intuitions are not honed to handle them.

In the spirit of Heil's response to original Swampman, one might think that Sorting Swampman is a reductio of externalism. The argument would go like this: If externalism is right, then Sorting Swampman has no intentional states when it accretes from muck on its swamp planet; its states do not causally depend on Davidson's in the right way. Yet the Sorting Swampman chosen by God and sent to Earth does causually depend on Davidson, so it does have intentional states. Surely God's selecting the body and moving it can't give it intentionality!

I find this unpersuasive, because I do not have any clear intuitions about what to say about Sorting Swampman - either before or after God has selected it. I am willing to draw out consequences of views I accept for other reasons and apply them to this case, but I am not willing to accept anything new on the basis of the Sorting Swampman scenario. As I said at the beginning, that would be analytic philosophy at its worst.

Perhaps more importantly than what it says about externalism, this line of thinking shows it is impossible for an omnipotent God to make the original Swampman scenario occur. He can only make Fiat Swampman or Sorting Swampman happen, but - as we've seen - those just aren't the same.

To put the upshot in a slightly misleading way: God can bring people back from the dead, but he can't make a zombie.