(this argument is paraphrased from:
http://www.closertotruth.com/video-prof ... tinga-/593)


1) For any x and y, if x is identical to y, then x and y have all the same properties. (Identity of Indiscernibles[1])
2) Possibly, my mind exists without my body.
3) So, my mind has the property "possibly exists when my body does not".
4) my body does not have the property "possibly exists when my body does not".
5) Therefore, my mind and my body do not have all the same properties.
6) Therefore, my mind and my body are not identical.

(1) is somewhat uncontroversial, and prima facie true. There are some possible objections deep within metaphysics however.

The "possibly" in (2) is the modal operator "◊". This just means that it is not necessarily false, in the same sense that "2+2=5" would be necessarily false. [2][3]

(3) just states (2) as a property.

(4) is true because of the law of non-contradiction; that is, if we call my body "B" it is necessarily false that B exists and does not exist(at the same time and in the same respect).

(5) follows from (3) and (4).

(6) follows from (1) and (5).

[1] http://plato.stanford.edu/archives/fall ... scernible/
[2] http://plato.stanford.edu/archives/fall ... stemology/
[3] http://plato.stanford.edu/archives/fall ... gic-modal/

I reject (2). Nonetheless the conclusion is no more controversial than saying that my hand and my body have different properties and are therefore not identical. Doesn't make my hand non-material.

Jef wrote:I reject (2).

Care to elaborate?

Jef wrote:
Nonetheless the conclusion is no more controversial than saying that my hand and my body have different properties and are therefore not identical.

I think most people would consider dualism a bit more controversial than that.

Nocterro wrote:

Jef wrote:I reject (2).

Care to elaborate?

I do not consider it possible for my mind to exist without my body, except perhaps in the same trivial sense that one can have a disembodied hand; i.e. I could be a brain in a vat. Other than that, my mind is just another functional part of my body.

Jef wrote:
Nonetheless the conclusion is no more controversial than saying that my hand and my body have different properties and are therefore not identical.

I think most people would consider dualism a bit more controversial than that.

Yes, but the argument doesn't show dualism, even if accepted. It just shows that my mind doesn't have identical properties to my body. Well, neither does my foot, but I'm pretty sure that was material last time I put my weight on it. Neither do the literally billions of things that aren't any part of my body, and which will continue to exist long after it has passed away.

bookmarking.

Jef wrote:
I do not consider it possible for my mind to exist without my body, except perhaps in the same trivial sense that one can have a disembodied hand; i.e. I could be a brain in a vat. Other than that, my mind is just another functional part of my body.

The argument still works given this. The modal possibility is only used to establish a property("possibly exists when B does not").

Jef wrote:
Yes, but the argument doesn't show dualism, even if accepted. It just shows that my mind doesn't have identical properties to my body. Well, neither does my foot, but I'm pretty sure that was material last time I put my weight on it.

That's fine. This is not an argument for any specific type of dualism, it just concludes that the mind and body are not identical. You could replace "body" with "brain", even. This argument is a "starting point" in building a case for dualism.

aspire1670 wrote:

Nocterro wrote:

Jef wrote:
I do not consider it possible for my mind to exist without my body, except perhaps in the same trivial sense that one can have a disembodied hand; i.e. I could be a brain in a vat. Other than that, my mind is just another functional part of my body.

The argument still works given this. The modal possibility is only used to establish a property("possibly exists when B does not").

Still works given that I don't accept that it is possible? I think not.

Jef wrote:
Yes, but the argument doesn't show dualism, even if accepted. It just shows that my mind doesn't have identical properties to my body. Well, neither does my foot, but I'm pretty sure that was material last time I put my weight on it.

That's fine. This is not an argument for any specific type of dualism, it just concludes that the mind and body are not identical. You could replace "body" with "brain", even. This argument is a "starting point" in building a case for dualism.

Well, if you mean it in the same sense that my hand is not my foot, then fine. But they are both constituent parts of my body, considered as a whole - as is my mind.

...methinks I smell equivocation on the horizon.

Nocterro wrote:2) Possibly, my mind exists without my body.

Most of the accumulated data on the brain indicates that it being damaged affects the mind. While (2) is possible, I consider it, and I believe you should as well, so unlikely that we should reject the idea until some evidence comes along.

Jef wrote:Still works given that I don't accept that it is possible? I think not.

Loren Michael wrote:
Most of the accumulated data on the brain indicates that it being damaged affects the mind. While (2) is possible, I consider it, and I believe you should as well, so unlikely that we should reject the idea until some evidence comes along.

Keep in mind that the property in question is "possibly exists when the body does not".

If you want to claim that the mind does not have this property, you have to show it's necessarily false.

Let me fix this for you, Nocterro:

1) For any x and y, if x is identical to y, then x and y have all the same properties. (Identity of Indiscernibles[1])
2) Possibly, my mind exists without my body.
3) So, my mind possibly has the property "exists when my body does not".
4) My body does not have the property "exists when my body does not".
5) Therefore, my mind and my body might not have all the same properties.
6) Therefore, my mind and my body might not be identical.

And (6) is only true because you assumed it in (2).

Chrisw wrote:Let me fix this for you, Nocterro:

1) For any x and y, if x is identical to y, then x and y have all the same properties. (Identity of Indiscernibles[1])
2) Possibly, my mind exists without my body.
3) So, my mind possibly has the property "exists when my body does not".
4) My body does not have the property "exists when my body does not".
5) Therefore, my mind and my body might not have all the same properties.
6) Therefore, my mind and my body might not be identical.

And (6) is only true because you assumed it in (2).

No, your property in (3) is different than my property.

Do you claim that my mind does NOT have the property "possibly exists when my body does not"?

Nocterro wrote:

Chrisw wrote:Let me fix this for you, Nocterro:

1) For any x and y, if x is identical to y, then x and y have all the same properties. (Identity of Indiscernibles[1])
2) Possibly, my mind exists without my body.
3) So, my mind possibly has the property "exists when my body does not".
4) My body does not have the property "exists when my body does not".
5) Therefore, my mind and my body might not have all the same properties.
6) Therefore, my mind and my body might not be identical.

And (6) is only true because you assumed it in (2).

No, your property in (3) is different than my property.

Do you claim that my mind does NOT have the property "possibly exists when my body does not"?

Is the possibility of a property, a property in itself?

I would say so, yes. (at least in the modal sense).

Nocterro wrote:I would say so, yes. (at least in the modal sense).

My car is red. I could paint it green. Is possibly green a property of my car?

Jef wrote:

Nocterro wrote:I would say so, yes. (at least in the modal sense).

My car is red. I could paint it green. Is possibly green a property of my car?

Yes.

Nocterro wrote:

Jef wrote:Still works given that I don't accept that it is possible? I think not.

Loren Michael wrote:
Most of the accumulated data on the brain indicates that it being damaged affects the mind. While (2) is possible, I consider it, and I believe you should as well, so unlikely that we should reject the idea until some evidence comes along.

Keep in mind that the property in question is "possibly exists when the body does not".

If you want to claim that the mind does not have this property, you have to show it's necessarily false.

The issue is that when one of your premises is this low on the probability scale, the entire argument shifts down as well. I mean, I'm agnostic on all kinds of weird stuff, but I don't entertain the possibility of any particular unlikely thing because of the low probability of most of said weird stuff. The stuff I care to talk about is the things I perceive as high probability weird stuff.

Unless you can bump up the likelihood of (2), "Argument for Dualism" is really just "Unlikely Argument for Dualism" and there are plenty of those already.

Nocterro wrote:

Chrisw wrote:Let me fix this for you, Nocterro:

1) For any x and y, if x is identical to y, then x and y have all the same properties. (Identity of Indiscernibles[1])
2) Possibly, my mind exists without my body.
3) So, my mind possibly has the property "exists when my body does not".
4) My body does not have the property "exists when my body does not".
5) Therefore, my mind and my body might not have all the same properties.
6) Therefore, my mind and my body might not be identical.

And (6) is only true because you assumed it in (2).

No, your property in (3) is different than my property.

Do you claim that my mind does NOT have the property "possibly exists when my body does not"?

That isn't a property. My version was a restatement of it that picked out a real property. Though what I actually should have said was:

3) My mind possibly has the property "is capable of existing when my body does not".

Existence as such isn't a property.

If possibly being a certain way could be a property then (1) would be false.

For example take Jef's "possibly green" car. Suppose he had two of them. Are they identical in colour? Possibly, but only possibly.

Nocterro wrote:

Jef wrote:

Nocterro wrote:I would say so, yes. (at least in the modal sense).

My car is red. I could paint it green. Is possibly green a property of my car?

Yes.

So in order to be accurate I should describe my car as 'red, possibly green, possibly purple, possibly polka dotted' and so on ad infinitum? No. My car is wholly red. It cannot possibly be green at this time due to the law of non-contradiction.

Basically, the problem you have is that while green is a property, 'possibly green' isn't; not until it becomes actually green.

Personally, I think the only reason anyone would want to put the word possibly into an argument of the kind you have made is that they don't want to openly state 'my mind can exist without my body' and have to defend that blunt premise. People like wiggle room. Nonetheless, either your mind can exist without your body, or it cannot.