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Carinthium comments on Skepticism about Probability - Less Wrong Discussion
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Comments (129)
Probability itself being somehow valid is something I do not think rationally legitimate. Therefore, in a sense yes but in a sense no.
In that case, I don't know how to proceed until you formulate your skepticism more precisely. What exactly is it that is not justified, if "skepticism wins"?
Nothing is justified if skepticism wins. Unless we have irrational faith in at least one starting assumption (and it is irrational since we have no basis for making the assumption), it is impossible to determine anything except our lack of knowledge.
So on thought, yes. There is never any valid rational reason to discriminate between possibilities because nothing can demonstrate the Evil Demon Argument false.
OK. I am still not exactly sure what you mean by "justification." Let's put this in more concrete terms. Imagine the following:
What does the Evil Demon Argument (and all in its family) say about the rationality of each choice, compared to the others (assuming it says anything at all)?
What advice would you personally give someone sitting at such a dinner table, and why?
The Evil Demon Argument says that you don't know that it's actually those three things before you. Further, it says that you don't know that eating the rice will actually have the effects you're used to, or that your memories can be used to remember your preferences. Etc etc...
On reason, I would give no advice. On faith, I would say to have the rice.
So, which advice would you give?
In the real world, it depends. With most people in practice, assuming they have enough of an understanding of me to know I am a skeptic on these things and are implicitly asking for one or the other, I give that. Therefore I normally give advice on faith.
I guess it's hard for me to understand what's irrational about advising them to eat the rice (as you indicated you would do). It seems like the only sane choice. I'm not sure exactly what you mean by "faith", but if advising people to eat the rice is based on it, then it must be compatible with rationality, right?
Right--choose the rice, assuming you (or they) want to live. That seems like the only sane choice, doesn't it?
Maybe this is a problem of terminology. You seem to be using the labels "faith" and "reason" in certain ways. Especially, you seem to be using the label "reason" to refer to the following of certain rules, but which you can't see how to justify.
Maybe instead of focusing on those rules (whatever they may happen to be), you should focus on why the rules are valuable in the first place (if they are). Presumably, it's because they reliably lead to success in achieving one's goals. The worth of the rules is contingent on their usefulness; it's not rational to believe only things you can prove with absolute certainty, because that would mean believing nothing, doing nothing, dying early and having no fun, and nobody wants that!
(In case you haven't read it, you might want to check you Newcomb's Problem and Regret of Rationality, from 2008.)
My conception of reason is based on determining what is true, completely and entirely irrespective of pragmatism. To call skeptical arguments irrational and call an anti-skeptical case rational would mean losing sight of the important fact that ONLY pragmatic considerations lead to the rejection of skepticism.
Rationality, to me, is defined as the hypothetical set of rules which reliably determine truth, not by coincidence, but because they must determine truth by their nature. Anything which does not follow said rules are irrational. Even if skepticism is false, believing in the world is irrational for me (and you, based on what I've heard from you and my definition) because nothing necessarily leads to a correlation between the senses and reality.
One of the rules of my rationality is that pragmatic considerations are not to be taken into account, as what is useful to believe and what is true have no necessary correlation. This applies for anything which has no necessary correlation with what is true.
What you're talking about is pragmatic, not rational. It is important to be aware of the distinction between what one may 'believe' for some reason and what is likely to be actually true, completely independent of such beliefs.
You seem to be referring to the distinction between instrumental and epistemic rationality. Yes, they are different things. The case I am trying to make does not depend on a conflation of the two, and works just fine if we confine ourselves to epistemic rationality, as I will attempt to show below.
OK, so I think your labeling system, which is clearly different from the one to which I am accustomed, looks like this:
and
If that's how you want to use the labels in this thread, fine. But it seems that an agent that believed only things that were known with infinite certainty would suffer from a severe truth deficiency. Even if such an agent managed to avoid directly accepting any falsehoods, she would fail to accept a vast number of correct beliefs. This is because much of the world is knowable--just not with absolute certainty. She would not have a very accurate picture of the world.
And this is not just because of "pragmatics"; even if the only goal is to maximize true beliefs, it makes no sense to filter out every non-provable proposition, because doing so would block too many true beliefs.
Perhaps an analogy with nutrition would be helpful. Imagine a person who refused to ingest anything that wasn't first totally proven to be nutritious. Whenever she was served anything (even if she had eaten the same thing hundreds of times before!), she had to subject it to a series of time-consuming, expensive, and painstaking tests.
Would this be a good idea, from a nutritional point of view? No. For one thing, it would take way too long--possibly forever. And secondly (and this is the aspect I'm trying to focus on) lots of nutritious things cannot be proven so. Is this bite of pasta going to be nutritious? What about the next one? And the one after that? A person who insisted on such a diet would not eat very nutrients at all, because so many things would not pass the test ( and because the person would spend so much time testing and so little time eating).
Now, how about a person's epistemic diet--does it make sense, from a purely epistemic perspective, for an agent to believe only what she can prove with absolute certainty? No. For one thing, it would take way too long--possibly forever. And secondly, lots of true things cannot be proven so, at least not with the kind of transcendent certainty you seem to be talking about. So an agent who insisted on such a filter would end up blocking much truth, thus "learning" a highly distorted map.
If the agent is interested in truth, she should ditch that filter and find a standard that lets her accept more true correct claims about the world, even if they aren't totally proven.
By the way, have you read many of the Sequences? They are quite helpful and much better written than my comments. I'd say to start here. This one and this one also heavily impinge on our topic.