1 of 17
1
Necessity
Posted: 11 April 2007 07:58 PM   [ Ignore ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

I’d like to explore necessity.

I’ll start by saying I know I don’t understand it.

I’ll take a quote from Doug to get the ball rolling.

[quote:1ded36807c=“dougsmith”]

I don’t really know how to make any normal sense of a world in which everything happens necessarily—

But I don’t think this is a real possibility.[/quote:1ded36807c]

In my mind in the actual world everything does happen necessarily.

But I don’t have a problem believing their are many possible worlds.

Is this a contradiction?

http://en.wikipedia.org/wiki/Modal_logic

[color=darkblue:1ded36807c]In the most common interpretation of modal logic, one considers "all logically possible worlds". If a statement is true in all possible worlds, then it is a necessary truth. If a statement happens to be true in our world, but is not true in all possible worlds, then it is a contingent truth. A statement that is true in some possible world (not necessarily our own) is called a possible truth.

Whether this "possible worlds idiom" is the best way to interpret modal logic, and how literally this idiom can be taken, is a live issue for metaphysicians. For example, the possible worlds idiom would translate the claim about Bigfoot as "There is some possible world in which Bigfoot exists". To maintain that Bigfoot’s existence is possible, but not actual, one could say, "There is some possible world in which Bigfoot exists; but in the actual world, Bigfoot does not exist". But it is unclear what it is that making modal claims commits us to. Are we really alleging the existence of possible worlds, every bit as real as our actual world, just not actual? David Lewis made himself notorious by biting the bullet, then asserting that possible worlds are as real as our own. This position is called "modal realism". Unsurprisingly, most philosophers decline to sign on to this ontologically extravagant doctrine, preferring to seek various ways to paraphrase away the ontological commitments implied by our modal claims.[/color:1ded36807c]

There are possible worlds in which big foot exists but in the actual world he doesn’t.

I view other possible worlds as imaginary not real. Although they are imaginary, I think they could exist but don’t or if they do it makes no difference to us as we are in the actual world.

I’m sure I seem to be muddled up, well I think I am.

Any thoughts?

Stephen

Profile
 
 
Posted: 12 April 2007 01:17 AM   [ Ignore ]   [ # 1 ]
Administrator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  15305
Joined  2006-02-14

Re: Necessity

[quote author=“StephenLawrence”]In my mind in the actual world everything does happen necessarily.

But I don’t have a problem believing their are many possible worlds.

Is this a contradiction?

Yes, assuming that the “many possible worlds” you believe in are all different.

 Signature 

Doug

-:- -:—:- -:—:- -:—:- -:—:- -:—:-

El sueño de la razón produce monstruos

Profile
 
 
Posted: 12 April 2007 03:09 AM   [ Ignore ]   [ # 2 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

Re: Necessity

[quote author=“dougsmith”][quote author=“StephenLawrence”]In my mind in the actual world everything does happen necessarily.

But I don’t have a problem believing there are many possible worlds.

Is this a contradiction?

Yes, assuming that the “many possible worlds” you believe in are all different.

Ok.

Now assuming there are many possible worlds and in some of them big foot exists but he doesn’t exist in the actual world, can I make the following statements without contradicting myself.

Big foot might be in the actual world.

It is not possible that he is in the actual world.

Oh and one more question.

If somebody is a hard determinist does that mean that they think everything happens necessarily?

Stephen

Profile
 
 
Posted: 12 April 2007 03:29 AM   [ Ignore ]   [ # 3 ]
Administrator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  15305
Joined  2006-02-14

Re: Necessity

[quote author=“StephenLawrence”]Now assuming there are many possible worlds and in some of them big foot exists but he doesn’t exist in the actual world, can I make the following statements without contradicting myself.

Big foot might be in the actual world.

It is not possible that he is in the actual world.

This is confused.

First off, “might be” means “possibly is”. So the two sentences you cite are mutually contradictory.

Secondly, possible worlds talk is an analysis of possibility. That is, to say “possibly X” JUST IS to say “in some world X”.

So if bigfoot exists in some world, then it is possible that bigfoot exist.

There are two things you might mean by the odd locution “possible in the actual world.” One of them is uncontroversial, the other is incoherent.

The uncontroversial reading is that if X is possible, X is possible in the actual world. So if it is possible that bigfoot exists (= if bigfoot exists in some possible world) then it is possible that he exists in the actual world. That’s just to say it’s possible that some other world was actual. That’s perfectly sensible and uncontroversial.

The incoherent reading is that one hold that the actual world is the only possibly actual world, and ask: “In THIS world is it possible that bigfoot existed?” Well, if the actual world is the only one that can be actual, then in fact there is only one possible world—the actual one—and then it is incoherent to say that bigfoot “could have” existed. It is also incoherent to say that bigfoot could have existed in the actual world.

[quote author=“StephenLawrence”]If somebody is a hard determinist does that mean that they think everything happens necessarily?

Not familiar with the description “hard determinist”, though it sounds plausible.

 Signature 

Doug

-:- -:—:- -:—:- -:—:- -:—:- -:—:-

El sueño de la razón produce monstruos

Profile
 
 
Posted: 12 April 2007 04:50 AM   [ Ignore ]   [ # 4 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

Ok.

Hopefully with your help I’ll get there.

It is true that big foot is not in the actual world.

Therefore it is impossible for him to be in the actual world because we know that he isn’t, given that he isn’t, it is not possible that he is.

Is this true a contradiction or confusion?

Stephen

Profile
 
 
Posted: 12 April 2007 05:59 AM   [ Ignore ]   [ # 5 ]
Administrator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  15305
Joined  2006-02-14

[quote author=“StephenLawrence”]It is true that big foot is not in the actual world.

Therefore it is impossible for him to be in the actual world because we know that he isn’t, given that he isn’t, it is not possible that he is.

Is this true a contradiction or confusion?

You’re just repeating the same confusion you had before. It’s possible that another world be actual.

 Signature 

Doug

-:- -:—:- -:—:- -:—:- -:—:- -:—:-

El sueño de la razón produce monstruos

Profile
 
 
Posted: 12 April 2007 06:24 AM   [ Ignore ]   [ # 6 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

[quote author=“dougsmith”][quote author=“StephenLawrence”]It is true that big foot is not in the actual world.

Therefore it is impossible for him to be in the actual world because we know that he isn’t, given that he isn’t, it is not possible that he is.

Is this true a contradiction or confusion?

You’re just repeating the same confusion you had before. It’s possible that another world be actual.

Ok.

So can it make sense to say that it is true that big foot does not exist in the actual world?

Stephen

Profile
 
 
Posted: 12 April 2007 06:38 AM   [ Ignore ]   [ # 7 ]
Administrator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  15305
Joined  2006-02-14
[quote author=“StephenLawrence”]So can it make sense to say that it is true that big foot does not exist in the actual world?

To be absolutely clear, it is true that bigfoot does not exist in THIS world, and THIS world happens to be the actual world, though it need not have been.

 Signature 

Doug

-:- -:—:- -:—:- -:—:- -:—:- -:—:-

El sueño de la razón produce monstruos

Profile
 
 
Posted: 12 April 2007 07:03 AM   [ Ignore ]   [ # 8 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

[quote author=“dougsmith”]

To be absolutely clear, it is true that bigfoot does not exist in THIS world, and THIS world happens to be the actual world, though it need not have been.

OK, so the problem seems to be with my laymans view of possibility. I’m trying to get a handle on the difference between these two views.

Is it true to say this.

It is true that big foot does not exist in this world.

Therefore if somebody offered me odds of a million to 1 on big foot existing in this world, assuming my only aim of betting would be to try and win the bet, it would be pointless betting because I could not win?

Is it true to say if I was to take on such a bet, given the fact I knew that big foot does not exist in this world, I would be a fool.

Or would odds of a million to one be in some way attractive to me?

Stephen

Profile
 
 
Posted: 12 April 2007 07:47 AM   [ Ignore ]   [ # 9 ]
Administrator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  15305
Joined  2006-02-14

I dunno, Stephen, that’s a different question—one of epistemology rather than metaphysics. I mean, when I say “bigfoot doesn’t exist in this world”, I am making a not-entirely-absolute claim. I mean, I don’t think bigfoot exists. But is there a two-in-a-million chance that he does? I’d say no, but it’s no longer entirely so clear.

Of course, if you had some sort of ‘god’s eye view’, and as a result already knew for sure, then the bet would be useless. If bigfoot doesn’t exist, that means there’s a ZERO in a million chance that he does.

 Signature 

Doug

-:- -:—:- -:—:- -:—:- -:—:- -:—:-

El sueño de la razón produce monstruos

Profile
 
 
Posted: 12 April 2007 08:45 AM   [ Ignore ]   [ # 10 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

[quote author=“dougsmith”]I dunno, Stephen, that’s a different question—one of epistemology rather than metaphysics. I mean, when I say “bigfoot doesn’t exist in this world”, I am making a not-entirely-absolute claim. I mean, I don’t think bigfoot exists. But is there a two-in-a-million chance that he does? I’d say no, but it’s no longer entirely so clear.

Of course, if you had some sort of ‘god’s eye view’, and as a result already knew for sure, then the bet would be useless. If bigfoot doesn’t exist, that means there’s a ZERO in a million chance that he does.

If big foot doesn’t exist in the actual world there is a zero in a million chance that he exists in the actual world. We agree on that.

i also agree that neither of us can make the absolute claim that big foot does not exist in the actual world because we cannot know with certainty that this is true.

This is the bit I don’t understand.

How can it make sense to say that it is true that big foot doesn’t exist in the actual world, given that we don’t know whether he does or he doesn’t? 

When in philosophy we say something is true is that not an absolute claim?

Profile
 
 
Posted: 12 April 2007 08:55 AM   [ Ignore ]   [ # 11 ]
Administrator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  15305
Joined  2006-02-14

[quote author=“StephenLawrence”]How can it make sense to say that it is true that big foot doesn’t exist in the actual world, given that we don’t know whether he does or he doesn’t? 

When in philosophy we say something is true is that not an absolute claim?

Not sure what you mean. People in philosophy say what they believe just like anyone else ... if we think that X is very probable, we’ll say, “I believe X”. That’s how belief works.

As for the notion of an “absolute claim”... The only absolute claims I make have to do with logic and mathematics. Empirical claims may be very probable (and some are very, very probable indeed), but can always be false.

 Signature 

Doug

-:- -:—:- -:—:- -:—:- -:—:- -:—:-

El sueño de la razón produce monstruos

Profile
 
 
Posted: 12 April 2007 09:12 AM   [ Ignore ]   [ # 12 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

[quote author=“dougsmith”][quote author=“StephenLawrence”]How can it make sense to say that it is true that big foot doesn’t exist in the actual world, given that we don’t know whether he does or he doesn’t? 

When in philosophy we say something is true is that not an absolute claim?

Not sure what you mean. People in philosophy say what they believe just like anyone else ... if we think that X is very probable, we’ll say, “I believe X”. That’s how belief works.

As for the notion of an “absolute claim”... The only absolute claims I make have to do with logic and mathematics. Empirical claims may be very probable (and some are very, very probable indeed), but can always be false.

What I’m asking is, what does “it is true” mean in this case?

Stephen

Profile
 
 
Posted: 12 April 2007 09:26 AM   [ Ignore ]   [ # 13 ]
Administrator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  15305
Joined  2006-02-14

Short answer: “X is true” means X is true.

Another short answer: “X is true” means X.

A somewhat longer answer: “X is true” means there is a truth-making correspondence relation between “X” and features of reality.

 Signature 

Doug

-:- -:—:- -:—:- -:—:- -:—:- -:—:-

El sueño de la razón produce monstruos

Profile
 
 
Posted: 12 April 2007 04:25 PM   [ Ignore ]   [ # 14 ]
Moderator
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  4052
Joined  2006-11-28

I’m no philosopher, but to me absolute truth only exists inside self-referential systems where one can first set the rules, such as mathematics. 2+2=4 because that’s built into the definitions of the terms. I agree with what I think Doug is saying, that the more ordinary use of the idea that something is true means “true to the best of my knowledge” or “true with a high degree of probability.” To say something is true doesn’t ordinarily mean there is absolutely no possibility of it being false, only that one considers this possibility so small as to be irrelevant. I can say Bigfoot doesn’t exist and yet allow the negligible possibility I might be wrong without contradicting myself in any meaningful way.

 Signature 

The SkeptVet
The SkeptVet Blog
Militant Agnostic: I don’t know, and neither do you!

Profile
 
 
Posted: 12 April 2007 09:33 PM   [ Ignore ]   [ # 15 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5939
Joined  2006-12-20

Hi Brennan

I don’t know what I think which is why I’m asking.

[quote author=“mckenzievmd”]I’m no philosopher, but to me absolute truth only exists inside self-referential systems where one can first set the rules, such as mathematics. 2+2=4 because that’s built into the definitions of the terms.

Ok so absolute truth exists inside self- referential systems.

In the case of big foot, does an absolute truth of the matter exist but we can’t know what it is, or is there no absolute truth of the matter?

I agree with what I think Doug is saying, that the more ordinary use of the idea that something is true means “true to the best of my knowledge” or “true with a high degree of probability.” To say something is true doesn’t ordinarily mean there is absolutely no possibility of it being false, only that one considers this possibility so small as to be irrelevant. I can say Bigfoot doesn’t exist and yet allow the negligible possibility I might be wrong without contradicting myself in any meaningful way.

So if we consider two statements.

Big foot does not exist.

The possibility of big foot existing is very very small.

These both mean the same thing, is that right?

Stephen

Profile
 
 
   
1 of 17
1