As regular readers know, I generally focus on economic issues. Often I do it as an economist; often I do it from a libertarian perspective.

But I want to point out a powerful essay on a philosophical issue, “The Brennan Thought Experiment: Further Explorations,” published today on by my friend, Ross Levatter. A comment on this belongs on Econlog because the essay has some economic overtones.

Let me explain.

Jason Brennan, a highly productive political theory professor at Georgetown, has been highlighting a philosophical thought experiment that he thinks sheds some light on an interesting philosophical issue: Should libertarians support free markets because free markets are what you end up with when you support the moral principle of non-aggression (from which you should never deviate), or should libertarians support free markets only to the extent (empirically, quite a large extent) that free markets lead to the best social results? Although it is an interesting and important question, I was uncomfortable with his particular thought experiment to get at the question. Something seemed wrong, and, in a hurry with other projects, I didn’t take time to figure it out. But when Levatter critiqued it in September, I commented online, saying his critique was “Fantastic.” I thought he had nailed it.

It turns out that Brennan disagreed, suggesting that Ross was “widely misinformed” about the state of economics.

“Wow,” I thought. “Does that mean that if I thought it was fantastic, that I’m widely misinformed about the state of economics!?” That’s possible, I guess, but it seemed unlikely.

But now Levatter has extended his argument, listing a full dozen problems with the Brennan thought experiment.

Levatter’s #3 is one of my favorites:

3. What Happens When We Change ONE Word?

There are other reasons to be skeptical of the claim Brennan’s thought experiment has anything to do with economics. Consider this variant thought experiment:

Imagine that a bunch of moral philosophers provide compelling evidence that life in a strictly libertarian polity would be a disaster. Imagine that they show conclusively that if people everywhere were to live in a Nozickian minimal state or a Rothbardian anarcho-capitalist civil society, with everyone strictly observing property right rules, that 10% of people would starve, 80% would be near subsistence, and only 10% would prosper.”

What has changed? Only that the term “economists” was replaced by the term “moral philosophers.” Notice I made NO changes to the economic arguments or rationales in the thought experiment, since there ARE NO economic arguments or rationales provided in Jason’s thought experiment, merely an assertion by “a bunch of economists,” just as, in this variant, there is an assertion by a bunch of moral philosophers. Moral philosophy is, like economics, at least in part an empirical subject. It is not like logic, after all. So, as Brennan might put it, “[t]here’s some possibility, and perhaps even some non-zero probability” that a bunch of moral philosophers might provide compelling evidence for this claim.

So the question of interest is: Is this a completely different thought experiment, or a slight variation of the original thought experiment? People can make up there own minds, but it seems obvious to me that this is but a minor variant of the original. Granted, per arguendo, it is easy for Brennan to imagine markets stink, but is it easy to imagine lots of people giving one answer to his original query, and yet a significantly different answer to my variant? Is it easy to imagine lots of libertarians saying, “Oh, well if a bunch of ECONOMISTS asserted 90% of the world would be immiserated by a minimal state, I would no longer favor it, but if a bunch of MORAL PHILOSOPHERS asserted 90% of the world would be immiserated by a minimal state, I’d still strongly favor it.”?

Now, if you agree that my variant thought experiment is really not significantly different from Brennan’s original, that is of course further evidence his is not a thought experiment about economics. It is a thought experiment about how one’s sensitivity to consequences-adverse, unexpected, highly unlikely, no-reason-provided-to-believe-accurate, stipulated consequences-impact on one’s advocacy of an otherwise-favored society.

My other favorite is argument #10, which is straight economics. Here’s an excerpt:

A fair reading of this graph is that everything we know from history indicates that moving toward a market economy moves us away from the entire prior experience of mankind, much worse than 90% of the populace immiserated and only 10% prospering. As we move to a world with comprehensive markets, we move to a world where these proportions are actually viewed as a bad thing rather than a blessing, where we routinely expect and receive much more. This is why I previously described Brennan’s thought experiment, where he imagines markets leading to the very result they historically eliminated as akin to a thought experiment where you imagine demand curves slope upward rather than down. Both are something no one has ever experienced. And this is why, above, I describe Brennan’s thought experiment as too severe to achieve his desired goals.

Argument #10 actually gets at the title of Brennan’s response to Levatter: “Imagine Markets Stink. It’s Easy if You Try.” It’s actually not that easy.

I think it is now up to Brennan to explain why he thinks his thought experiment is about economics at all.