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Radical Scepticism

Posted Jul 15, '14 at 8:06am

Moegreche

Moegreche

2,855 posts

Moderator

So I was going to make this the next topic in the Great Debates, but I figured it might be more fun in a more open format. Before getting to the discussion point, I should make a few things clear.

First, radical scepticism shouldn't be viewed as an actual position that philosophers hold. Instead, it is part of the dialectic that any theory of knowledge should be able to address. So if I develop some particular theory of knowledge, one of the desiderata it should meet it to provide an answer to the sceptical challenge.

Second, the sceptical challenge asks whether (and to what extent) we have knowledge. This is not to say that the sceptic is claiming that we don't know anything - that would be ridiculous! Very, very few philosophers would doubt that we know things such as "Triangles have 3 sides" or "Bachelors are unmarried". Instead, the sceptical challenge is focused on knowledge of the world around us - what we might call empirical knowledge.

So here's the sceptical argument:

1) If I know that I have hands, then I know that I'm not a handless brain-in-a-vat.
2) I don't know that I'm not a handless brain-in-a-vat.
3) Therefore, I don't know that I have hands.

This argument can be generalised to encompass pretty much any claim about the world around us (e.g. that I'm sitting here typing and not just a brain-in-a-vat). Here's what that would look like:

1) If I know very much at all, then I know I'm not a BIV.
2) I don't know I'm not a BIV.
3) Therefore I don't know very much at all.

There are a number of ways to attack the above argument(s), which I would like to be the focus of this thread. Rather than throwing a bunch of jargon in here, I'll just see where this thing goes (if anywhere!).

One helpful hint when looking to attack an argument. The two most important questions you have in your philosophy toolbelt are: 1) 'Is the argument valid?', and 2) 'Is the argument sound?'. (Feel free to take a look at my Introduction to Logic thread for definitions of validity and soundness.)

So the basic question: How can we avoid the above conclusion of radical scepticism?

 

Posted Jul 15, '14 at 11:07am

FishPreferred

FishPreferred

1,546 posts

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.

 

Posted Jul 15, '14 at 11:12am

partydevil

partydevil

5,109 posts

1) If I know that I have hands, then I know that I'm not a handless brain-in-a-vat.
2) I don't know that I'm not a handless brain-in-a-vat.
3) Therefore, I don't know that I have hands.

it seems that 2) is always overruling 1), so then 3) is always contradicting with 1).
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.
(i dunno the expression "brain-in-a-vat". so i'm sorry if what i said is ridicules =P )

 

Posted Jul 15, '14 at 1:24pm

09philj

09philj

1,251 posts

Where ignorance is bliss, 'tis folly to be wise.

- Thomas Gray

 

Posted Jul 15, '14 at 2:23pm

MattEmAngel

MattEmAngel

5,155 posts

Well, if radical skepticism in this case refers to the "if then therefore" 3-line argument, we can just prove that it is a fallacy (fallacy of composition, perhaps) and safely ignore it. Once it has been proved incorrect, anyone's choice to believe it or not is not our responsibility.

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.

Although I like Fish's response more.

 

Posted Jul 15, '14 at 2:27pm

FishPreferred

FishPreferred

1,546 posts

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.

This hinges on what you define as knowledge. "Knowing" that a conical cube cannot exist is not the same as "knowing" that Santa Clause cannot exist.

(i dunno the expression "brain-in-a-vat". so i'm sorry if what i said is ridicules =P )

It's a disembodied brain that is given fake sensory signals, making it believe it is a regular person, hypothetically.

 

Posted Jul 15, '14 at 5:38pm

MattEmAngel

MattEmAngel

5,155 posts

It's a disembodied brain that is given fake sensory signals, making it believe it is a regular person, hypothetically.

I honestly don't understand the significance of the "brain in a vat" argument. For the sake of it, let's say you are in fact a brain in a vat, connected to a supercomputer that makes it seem as though you are an entire person in a real world when in fact none of that exists.

So what?

What exactly does that change? The only thing I can think of is that it eliminates your need to follow "the rules," but that ruins the whole point and it comes off more as an excuse to do what you want without actual repercussions. But if you're committing nonexistent crimes, you're receiving nonexistent punishment, and in the end you wind up just as dead as you would be if you were a disembodied brain. You certainly can't live without food because you only think you're hungry.

Besides, even if you ARE a brain in a vat, what are you going to do about it? With no other physical bodily elements, you can't fight back against whatever machine you're connected to, and I would assume the creators of the aforementioned vat had made preparations for potential problems.

As odd as it may sound, so what? You might as well make the best of your nonexistent life. Even if love and happiness and comfort aren't real, it's better than deliberate pain, suffering and misery that aren't real, along with crime and punishment that aren't real. The only real difference is, once you die you'll be a dead brain in a vat instead of a dead human.

 

Posted Jul 15, '14 at 6:41pm

09philj

09philj

1,251 posts

As odd as it may sound, so what? You might as well make the best of your nonexistent life.

In any case, we have no idea how we would escape from it anyway. And it's better than being a brain in a vat. Also, who would want to wake up to a reality where they had been made to become a brain in a vat?

 

Posted Jul 15, '14 at 8:27pm

MattEmAngel

MattEmAngel

5,155 posts

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

 

Posted Jul 15, '14 at 10:57pm

FishPreferred

FishPreferred

1,546 posts

I honestly don't understand the significance of the "brain in a vat" argument.

It isn't about what you would do about it. The thought problem is only meant to explain how reality and perception can be altogether different.

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

Both spellings are correct. One is just more common.

 
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