Moore's Refutation of Skepticism

public hermit · 2025-08-21T00:54:56-0500

Famously, G.E. Moore held up his hand in front of the class and declared, "Here is a hand." And, by that declaration, Moore refuted epistemic skepticism.

What was he refuting?

If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).
S doesn't know that not-sk.
Therefore, S doesn't know that q (she has a hand). - modus tollens

What was Moore declaring?

If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).
S knows that q.
Therefore, S knows that not-sk (skepticism is false). - modus ponens

Does that argument work? Can I just raise my hand, and wave away all the brain-in-a-vat, Cartesian-daemon possibilities?

Here is one hand - Wikipedia

en.wikipedia.org

2PhiloVoid · 2025-08-21T09:14:01-0500

public hermit said:
Famously, G.E. Moore held up his hand in front of the class and declared, "Here is a hand." And, by that declaration, Moore refuted epistemic skepticism.

What was he refuting?

If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).

S doesn't know that not-sk.

Therefore, S doesn't know that q (she has a hand). - modus tollens

What was Moore declaring?

If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).

S knows that q.

Therefore, S knows that not-sk (skepticism is false). - modus ponens

Does that argument work? Can I just raise my hand, and wave away all the brain-in-a-vat, Cartesian-daemon possibilities?

Here is one hand - Wikipedia

en.wikipedia.org

I always loved that little rejoinder from G.E. Moore, particularly because---in a juvenile fashion---I adapted my own, scaled down single digit version of it for more general use.

Anyway, I think it works for what it was addressing on a Common Sense level, but that's mainly because he was only addressing the most extreme form of Skepticism.

Beyond this momentary conclusion, I'd have to pull out my papers on G.E. Moore from a few decades ago, as well as pull in some of what both Renee Descartes and Hillary Putnam suggested if we're going to go up Nihil Hill and jump into the Brain-In-A-Vat scenario.

I'd also like to see what anyone else here thinks about your epistemic inquiry regarding Moore's argument.

public hermit · 2025-08-21T09:43:20-0500

2PhiloVoid said:
Anyway, I think it works for what it was addressing on a Common Sense level, but that's mainly because he was only addressing the most extreme form of Skepticism.

That's a helpful point. He is addressing an extreme form. I also think it works on a common sense level. I guess the argument would work even if we were in a BIV world. Wouldn't I still know I had hands in the same way if I were a brain in a vat? Wouldn't it still be common sense in a BIV world? It kind of takes the bite out of skepticism, perhaps. Sure, it's a BIV world but nothing changes. I still type with my thumb, walk on two legs, recognize simple goodness (pace Moore), and so on.

public hermit · 2025-08-21T10:33:55-0500

2PhiloVoid said:
I always loved that little rejoinder from G.E. Moore, particularly because---in a juvenile fashion---I adapted my own, scaled down single digit version of it for more general use.

Ha! Yes, the abbreviated version is compelling.

essentialsaltes · 2025-08-21T12:36:51-0500

Both are begging the question.

The second premise is just a disguised version of the conclusion each person wants.

I mean, they're valid in form, but obviously it depends on the extent that you agree with that second premise.

public hermit · 2025-08-21T12:42:46-0500

essentialsaltes said:
Both are begging the question.

The second premise is just a disguised version of the conclusion each person wants.

I mean, they're valid in form, but obviously it depends on the extent that you agree with that second premise.

Yeah, I see what you're saying. That makes sense.

ETA: I think each would appeal to some other argument to support their second premise. In the case of the epistemic skeptic, it might be something like BIV or an evil-demon/genius. For Moore it's raising his hands. But, do those save them from begging the question? I don't know.

2PhiloVoid · 2025-08-21T13:51:25-0500

public hermit said:
That's a helpful point. He is addressing an extreme form. I also think it works on a common sense level. I guess the argument would work even if we were in a BIV world. Wouldn't I still know I had hands in the same way if I were a brain in a vat? Wouldn't it still be common sense in a BIV world? It kind of takes the bite out of skepticism, perhaps. Sure, it's a BIV world but nothing changes. I still type with my thumb, walk on two legs, recognize simple goodness (pace Moore), and so on.

I don't know. Perhaps, but since I've just been informed by a source "who knows" that I'm apparently not a brain-in-a-vat and that I'm not spending enough time looking for employment, I guess reality is doing what it does best to let us know it's not just a facade: it bites us in the a$$.

So..................

Have a nice day everyone!

PloverWing · 2025-08-21T14:18:08-0500

I'm having trouble getting from "I believe that it is likely that I have a hand" to "I know I have a hand". I look forward to what other folks have to say in the discussion.

durangodawood · 2025-08-21T14:20:00-0500

public hermit said:
Famously, G.E. Moore held up his hand in front of the class and declared, "Here is a hand." And, by that declaration, Moore refuted epistemic skepticism.

What was he refuting?

If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).

S doesn't know that not-sk.

Therefore, S doesn't know that q (she has a hand). - modus tollens

What was Moore declaring?

If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).

S knows that q.

Therefore, S knows that not-sk (skepticism is false). - modus ponens

Does that argument work? Can I just raise my hand, and wave away all the brain-in-a-vat, Cartesian-daemon possibilities?

Here is one hand - Wikipedia

en.wikipedia.org

If you know you have a hand in the way we typically mean it, that means you have not chosen to accept skepticism about your hand.

Thats all I get from it. Nothing about skepticism being false. Just personal position re skepticism - which you may have adopted by mere unthinking custom.

durangodawood · 2025-08-21T14:51:53-0500

Moore's argument seems so blatantly poor that its got we wondering: what might I be missing. I mean, hes the philosophy pro. And I'm not.

Otoh, Ive seen the pro's make some quite bad arguments in support of positions they are personally attached to. William Lane Craig, Im looking at you....

public hermit · 2025-08-21T15:28:44-0500

durangodawood said:
Moore's argument seems so blatantly poor that its got we wondering: what might I be missing. I mean, hes the philosophy pro. And I'm not.

Otoh, Ive seen the pro's make some quite bad arguments in support of positions they are personally attached to. William Lane Craig, Im looking at you....

Yeah, maybe it is a blatantly poor argument. I think he's counting on his demonstration being so obvious that accepting the contrary position wouldn't make sense ("Moorean facts").

I think this is related (but not necessarily Moore's position). The epistemic skeptic he is addressing wants to say that things could be so radically different than they appear, that we shouldn't trust the appearances, either. It's a universal skepticism. An evil demon could arrange things so that we believe falsities that just happen to work. Or, I could be a brain in a vat and not have hands (only the experience of having hands). And since I don't know these things are not the case, I shouldn't trust common sense intuitions/normal appearances like "I have hands." But it's obvious that I have hands. Even if this were a creation of an evil demon or I were a brain in a vat, it wouldn't change the appearance or the common sense intuitions that we experience. So why doubt those? Even if things were radically different than they appear, nothing really changes. The reason for being skeptical kind of disappears, at least for me.

durangodawood · 2025-08-21T15:51:57-0500

public hermit said:
Yeah, maybe it is a blatantly poor argument. I think he's counting on his demonstration being so obvious that accepting the contrary position wouldn't make sense ("Moorean facts").

I think this is related (but not necessarily Moore's position). The epistemic skeptic he is addressing wants to say that things could be so radically different than they appear, that we shouldn't trust the appearances, either. It's a universal skepticism. An evil demon could arrange things so that we believe falsities that just happen to work. Or, I could be a brain in a vat and not have hands (only the experience of having hands). And since I don't know these things are not the case, I shouldn't trust common sense intuitions/normal appearances like "I have hands." But it's obvious that I have hands. Even if this were a creation of an evil demon or I were a brain in a vat, it wouldn't change the appearance or the common sense intuitions that we experience. So why doubt those? Even if things were radically different than they appear, nothing really changes. The reason for being skeptical kind of disappears, at least for me.

Pragmatically, for sure it makes sense to live and trust as if the "common sense" appearance*1 of things is real. But that doesn't make the proposals of radical skepticism false. It just renders them not worth serious consideration*2 in your life.

Footnote 1: There still are some going facts that do grind against common sense tho. Prior to Einstein who would have thought theres a way for a son to be actually older than the father? The ordering of events in a time sequence setting is about as common sense as it gets. Turns out it's not absolute at all.

Footnote 2: Simulation hypothesis throws a wrench into this by going beyond whats "possible" and makes a case about whats probable. Almost anything is "possible" in thats its hard to definitively disprove things proposed to occur at a level beyond human any reckoning. Simulation otoh tries to reason from facts on the ground or at least facts that could be actually knowable in some not too distant future. Still a lot of speculation there tho.

public hermit · 2025-08-21T17:06:18-0500

durangodawood said:
Pragmatically, for sure it makes sense to live and trust as if the "common sense" appearance*1 of things is real. But that doesn't make the proposals of radical skepticism false. It just renders them not worth serious consideration*2 in your life

I think that's a spot on analysis. But doesn't that mean the conclusion of skepticism is false, i.e., I should not trust current appearances?

I was also thinking about things related to Footnote 1. Does the relative nature of time undercut the pragmatic approach to everyday experience? Or does quantum mechanics mean I shouldn't trust that I have hands? These things put our everyday experience in a different light, for sure, but the pragmatic center still seems to hold.

To be fair, this seems to have been Moore's whole approach to "common sense." I like it, but I'm also not real confident it works.

durangodawood · 2025-08-21T17:32:49-0500

public hermit said:
I think that's a spot on analysis. But doesn't that mean the conclusion of skepticism is false, i.e., I should not trust current appearances?

I thought radical skepticism was strong limits on what we can fully know. But as for what we should provisionally believe so we can go about life, it claims nothing. Thats my possibly wrong understanding about what this is in philosophy world.

So in the absence of proof, believe what seems most reasonable for living a decent life.

public hermit said:
I was also thinking about things related to Footnote 1. Does the relative nature of time undercut the pragmatic approach to everyday experience? Or does quantum mechanics mean I shouldn't trust that I have hands? These things put our everyday experience in a different light, for sure, but the pragmatic center still serms to hold.

Time relativity doesnt demolish every common sense understanding of things, imo. It demolishes just one, and only in a way that doesnt even affect regular life (yet). But still, one "real common sense fact" of the world undercut is something.

public hermit said:
To be fair, this seems to have been Moore's whole approach to "common sense." I like it, but I'm also not real confident it works.

The pragmatic center works. But it doesnt hold as absolute knowledge that rules out alternative big picture explanations for all this. I mean, youre a Christian, right? To me that implies you believe some things that defy "look at my hands" common sense.

public hermit · 2025-08-21T17:43:58-0500

durangodawood said:
I thought radical skepticism was strong limits on what we can fully know. But as for what we should provisionally believe so we can go about life, it claims nothing. Thats my possibly wrong understanding about what this is in philosophy world.

No, I think that's right.

durangodawood said:
So in the absence of proof, believe what seems most reasonable for living a decent life.

Agreed.

durangodawood said:
Time relativity doesnt demolish every common sense understanding of things, imo. It demolishes just one, and only in a way that doesnt even affect regular life (yet). But still, one "real common sense fact" of the world undercut is something.

Okay, I agree with that.

durangodawood said:
The pragmatic center works. But it doesnt hold as absolute knowledge that rules out alternative big picture explanations for all this. I mean, youre a Christian, right? To me that implies you believe some things that defy "look at my hands" common sense.

I don't think so, but I'll have to think about that. Right off the bat, I think our common sense experience fits different assumptions, also. For instance, because of our epistemic limitations, I think this experience can fit both a BIV world and a creator-God world. That being said, because I do believe in a creator-God world, I feel pretty confident that our common sense experience is trustworthy for its own sake (God is good like that). However, I don't think a BIV world would make it somehow less trustworthy. It would still be the same experience, which works as well as it does.

durangodawood · 2025-08-21T17:47:11-0500

public hermit said:
...a BIV world....

Whats that?

public hermit · 2025-08-21T17:53:09-0500

durangodawood said:
Whats that?

Sorry. Brain in a vat.

Moore's Refutation of Skepticism

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