Forums

ForumsWorld Events, Politics, Religion, Etc.

Radical Scepticism

Posted Jul 16, '14 at 3:37am

09philj

09philj

1,228 posts

By the way, Moegreche, the word is "skepticism."

Both spellings are correct. One is just more common.

"Skepticism" is the US spelling. "Scepticism" is the UK and Commonwealth spelling. Moegreche is British. Thus, "Scepticism."

 

Posted Jul 16, '14 at 6:10am

Moegreche

Moegreche

2,854 posts

Moderator

Why would this need to be avoided? If what you refer to as knowledge is necessarily correct, this is the only rational thing to conclude.

I was super careful to avoid referring to a particular conception of knowledge - but you're right in that the answer to the sceptical challenge will depend on one's definition of knowledge.
The main point, however, is that the conclusion (which apparently follows from highly plausible premises) is incredibly unintuitive. So if you want to claim that we lack knowledge, you'll have to give some story about this cognitive state we take to be knowledge.

but what reasons are there for 2) to overrule 1)? cause 1) is a reason for 2) to be not true... you do know that your not a handless brain-in-a-vat.

Excellent! So we could claim that (2) is just false - we do know we're not brains-in-vats! On a technical note, the BIV scenario is called a sceptical scenario or sceptical hypothesis. And your strategy is called a Moorean response to the problem (after G.E. Moore). The general thought here is that we can know the negation of the sceptical hypothesis.

So your argument would run like this:

1) If I know that I have hands, then I know I'm not a handless BIV.
2) I know that I have hands.
3) Therefore, I know that I'm not a handless BIV.

Any thoughts on this sort of response?

In other words, the conclusion is (insert name of fallacy). Take it or leave it. It's not my problem, and I can't force you to change your mind anyway.

We can't attack the conclusion of a valid argument - we must attack one of the premises. Now, there's definitely not a fallacy of composition going on here, but there might be something fishy going on with premise (1).
The point here is to work to show there's something wrong with the argument - not just suggest vaguely that there is.
But on your general point, there are lots of moves we can make against premise (1). But we'll need to give some sort of story as to why it's false.

So what?

Fair enough! But the things that you're talking about are practical in nature rather than epistemic. I was hoping to explain the 'so what' factor in the OP, but I guess it wasn't clear. The basic idea is that we must engage with the sceptical challenge in order to develop a satisfactory account of knowledge.

Here's another way way of putting it. The sceptical challenge is saying that we must know the negation of sceptical hypotheses in order to know very much at all. Some claim (including me) that we can know that sceptical hypotheses are false. Others claim we can't, but that (1) is false. These two different approaches lead to very different conceptions of knowledge!

 

Posted Jul 17, '14 at 1:03pm

MageGrayWolf

MageGrayWolf

9,691 posts

Knight

Knowledge of my hands existing can only be reference from the stimuli I'm receiving, whether that stimuli be the result of actual hands or a simulated construct being fed to a brain in a vat.

I suppose one way to describe what I'm saying is like this dream I had the other day. I was lying on my bed  with my hands and arms across my chest. In the dream I heard a knock at the door and I could feel my left hand reach over and pick up a shirt next to me. At the same time I could also still feel my left hand lying across my chest. In the confines of that dream I had two superimposed left arm and hand. I can say that I know this, even though outside of that dream I don't.

 

Posted Jul 17, '14 at 1:32pm

MageGrayWolf

MageGrayWolf

9,691 posts

Knight

Just thought how I might be able to describe this a bit better.

Let's take Knowledge as justified true belief. Rather classic approach to it.
This about this is that true doesn't necessarily have to equate to real. Like in my dream it's true that I had two superimposed left arms, but that isn't real.

So it wouldn't matter if I really had hands or if my hands were just a product of a simulation being fed to me. It's still true within that stimuli. As such even if my hands are real or not the criteria for knowledge that I do can still be met, even if I was really a BIV.

 

Posted Jul 18, '14 at 5:37pm

Moegreche

Moegreche

2,854 posts

Moderator

This about this is that true doesn't necessarily have to equate to real. Like in my dream it's true that I had two superimposed left arms, but that isn't real.

So this a cool idea - we just mess with our theory of knowledge by adjusting the notion of truth. And this move makes sense. It's true to say that Harry Potter is a wizard, while it's false to say that he's rabid mongoose. But this only makes sense with respect to the Harry Potter world (i.e. the world described by the books). In the same way, we can say that P is true with respect to the world described by my perceptual experience.

So, here's a bad objection to this line:
Objection: If what's true is just what corresponds with my perceptual experience, then beliefs formed from visual hallucinations would still be true.

In other words, this objection is reading the view as if all there is to 'the world described by my perception' is just visual stimulation (i.e. what you're seeing). But it's more than that - it's even more that everything within your immediate experience. In fact, we could include many things that you believe and know (under this interpretation, of course). So things (like hallucinations) that don't cohere with your wider set of beliefs would be rejected as a belief in the first place - and thus they wouldn't even be in the market for knowledge ascriptions.

But there may be other, stronger objections to this view. Any thoughts?

 

Posted Jul 18, '14 at 9:04pm

MageGrayWolf

MageGrayWolf

9,691 posts

Knight

Objection: If what's true is just what corresponds with my perceptual experience, then beliefs formed from visual hallucinations would still be true.

In other words, this objection is reading the view as if all there is to 'the world described by my perception' is just visual stimulation (i.e. what you're seeing). But it's more than that - it's even more that everything within your immediate experience. In fact, we could include many things that you believe and know (under this interpretation, of course). So things (like hallucinations) that don't cohere with your wider set of beliefs would be rejected as a belief in the first place - and thus they wouldn't even be in the market for knowledge ascriptions.

There would be other means of gather perceptual information other than just visually that we could use to determine if what was being seen was real or not, for instance we could try and touch it. Relying on wider beliefs would also come into play in say, asking another person we already believe to be real if they see the hallucination.

With a hallucination we could still make true statements about it, even if we were to hold the false belief that the hallucination was real or even if we didn't.

 
Reply to Radical Scepticism

You must be logged in to post a reply!