Inference to the best explanation and skepticism

Inference to the best explanation is a really interesting philosophical topic.

Let's start the story with Descartes. Skepticism becomes an option--what if we're all being deceived? What if our eyes and ears are lying to us? Descartes tried to answer this question by starting with some firm knowledge and slowly justifying almost all of our knowledge from a few secure facts. In this way all our purported knowledge would be justified, and we would be allowed our confidence again.

As the story goes, not everyone agreed with Descartes secure truths. So other attempts at justifying our knowledge, at securing epistemology, began. Locke and Hume tried to justify human knowledge by matching all knowledge with observation. But, famously, this only gets you so far. So empiricism doesn't work to give us complete, skeptic-free confidence in our beliefs.

(Here I fudge the story a bit.) So what do you do now? Is it a free for all just because we don't have an answer to the skeptic? No, it's not. What we do is acknowledge that justification needs to end somewhere, and as it turns out justification for our beliefs ends before the point where we would feel totally secure in our beliefs. So there isn't any answer to the absolute skeptic. But that means we need to figure out where to stop.

So the game becomes trying to build your house as close to the cliff as possible. You lose if your house falls off the cliff, and you also lose if your house ends up looking like a mess. That is, the game is to find a starting point with as few assumptions as possible (satisfying a general desire for parsimony in the absence of justification) and building and justifying as much of our common-sense and scientific beliefs as possible. You lose if you end up with skepticism, and you also lose if you end up justifying silly beliefs, like beliefs in fairies or witches.

Right now I'm reading a paper where someone tries to say "We don't have to stop the trail of justification at inference to the best explanation. We have a way to justify inference to the best explanation that makes sense." As it turns out, that way of justifying inference to the best explanation is designed to allow for other kind of "inferences" besides inference to the best explanation. Specifically, it wants to allow for inference to the only things that make deliberation possible, which would include normative facts.

As far as I can tell, the debate about this paper has to be (obviously about the details of his argument, he needs to show lots of little points in order to get his big points into play) about whether he tried to go too far back. If his stopping point is no better than Inference to the Best Explanation, I think he'll find many people saying "Hmm, yeah that's interesting. I'm going to build my house right over here on ground that's a bit more secure, right here with Inference to the Best Explanation."

[His response will be, but building your house over there you still haven't made deliberation possible, but that's the second half of his debate. If the first point is dependent on the second, then he's got a very different argument on his hands.]

There's also a debate (that I know nothing about) where people wonder if inference to the best explanation is the right place to stop for reasons that have nothing to do with ethics.

Also, an observation: there are no arguments for mathematical or ethical realism that are particular to math or ethics. That's because realism itself isn't restricted to math or ethics. You win the realist game if you define plausible methods for coming to physical truths, and then use those same methods for reaching mathematical or ethical truths. This is exactly what inference to the best explanation/indispensability arguments do.