Can we have knowledge of the future?

[Bork]

Neither of my examples are logical tautologies.

They are necessarily true, but not by virtue of their logical form.

The problem that was posed was whether we can know anything about the future. The answer is yes because we can deduce necessary truths. Some of which are tautologies( my examples are not). Even if they were they still count as knowledge about the future, useful or not.

Now if he was asking whether we can know which possible future events will occur then the answer is also yes. Unless you are some kind of uber old fashion skeptic who thinks no inductive support can justify a belief. This person would also be commited to say we arent justified in believing that we have hands, or that we know our parent's names, or that physical objects exist, etc.

[peritonlogon]

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Neither of my examples are logical tautologies.

They are necessarily true, but not by virtue of their logical form.


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Actually what you said is true precisely because of it's logical form... Even if you did not write it down, or elucidate it.

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Tomorrow, nothing will exist which is both red all over, and green all over.

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If we can all except this proposition.

All logical forms that are true today are true any other day.

"Tomorrow, nothing will exist which is both red all over, and green all over"

Is true because of this identity


All-red-all over things are red-all-over things

and its converse

All non red-all over-things are non red all over things.

and this proposition.

A green all over thing is a non red-all-over thing.

Since, principle of non contradiction "A thing can not both be and not be in the same respect at the same time"

Which means, what you said is just a specific instance of the principle of non-contradiction, which is a rule of logic that is also provable by tautology.

[Bork]

Nothing that is red all over is green all over.

Its logical form is: Something that has property X cannot have property Y.

You can make substitutions which make this true and which make it false.
It is NOT true because of its form. It is not a logical tautology.

You seem to be confused about what logical form is so I will provide you with a couple links.
http://plato.stanford.edu/entries/logical-form/
http://plato.stanford.edu/entries/analytic-synthetic/

The above is completely tangential to the OP's question. The fact remains if you only accept deductive justification for knowledge then you better be an almost absolute epistemological skeptic. Almost every belief we form is the result of induction.

[peritonlogon]

The statement was that no logical form makes it so, not just tautology. The fact of the matter is that, as I said, this statement is simply a specific example of the logical rule of non-contradiction. Simply to state that things won't be contradictory in the future isn't really a deduction a of the future, only a deduction of logic. I'd write a proof, but I don't think it's worth my time.

[Bork]

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The statement was that no logical form makes it, so not just tautology.

[/ QUOTE ] You still dont know what logical form means and ignored my links which would have been helpful in this area.

Nothing can be both X all over and Y all over is not an instance of Nothing can be (X and not-X).

Do you believe its contradictory for something to be red all over and fuzzy all over? Its the same logical form as the statement you are claiming is an instance of a simple contradiction.

The contradiction does not come from merely the logical form but from the logical form in conjunction with the concept of colors.

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Simply to state that things won't be contradictory in the future isn't really a deduction a of the future, only a deduction of logic. I'd write a proof, but I don't think it's worth my time.

[/ QUOTE ] Well first it requires a deduction using logic and the concept of color to come to the conclusion that something that is red all over and green all over is impossible. Then you validly infer that necessarily impossible things things are impossible in the future. So yes you use logic in your deduction, but you certainly can make necessarily true statements about future states of affairs. I would really like to see your proof to the contrary.

[Bork]

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All logical forms that are true today are true any other day.

"Tomorrow, nothing will exist which is both red all over, and green all over"

Is true because of this identity


All-red-all over things are red-all-over things

and its converse

All non red-all over-things are non red all over things.

and this proposition.

A green all over thing is a non red-all-over thing.

Since, principle of non contradiction "A thing can not both be and not be in the same respect at the same time"

Which means, what you said is just a specific instance of the principle of non-contradiction, which is a rule of logic that is also provable by tautology.

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One more point.
Just because you used a tautology (you used more than one btw) in your 'proof' of my statement it does not follow that my statement itself is a a tautology or an instance of the the tautology that you invoked in the proof.

[chezlaw]

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Neither of my examples are logical tautologies.

They are necessarily true, but not by virtue of their logical form.

The problem that was posed was whether we can know anything about the future. The answer is yes because we can deduce necessary truths. Some of which are tautologies( my examples are not). Even if they were they still count as knowledge about the future, useful or not.



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They are necessarily true by virtue of the meaning of the parts. Thats what I mean by tautology, but lets not have an extremely dull conversation about that [img]/images/graemlins/smile.gif[/img]

The point remain, all you are saying is that you know that necessarily true propositions wont be false tomorrow.

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Now if he was asking whether we can know which possible future events will occur then the answer is also yes. Unless you are some kind of uber old fashion skeptic who thinks no inductive support can justify a belief. This person would also be commited to say we arent justified in believing that we have hands, or that we know our parent's names, or that physical objects exist, etc.

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I dont think thats what skeptics claim. Induction can support beliefs, one question is can it support knowledge. Even if you allow that induction can support knowledge then thats not enough to make knowledge possible.

chez

[Bork]

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I dont think thats what skeptics claim. Induction can support beliefs, one question is can it support knowledge. Even if you allow that induction can support knowledge then thats not enough to make knowledge possible.


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I dont understand what you mean by this.

Im simply saying if you think induction cannot justify knowledge, then you are commited to saying we only know very few present tense things. People who used this rationale when answering no to the OP must also believe we cannot know anything about past events either. Any justification for a past event requires induction. I claim this a defect in the rationale.

[chezlaw]

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I dont think thats what skeptics claim. Induction can support beliefs, one question is can it support knowledge. Even if you allow that induction can support knowledge then thats not enough to make knowledge possible.


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I dont understand what you mean by this.

Im simply saying if you think induction cannot justify knowledge, then you are commited to saying we only know very few present tense things. People who used this rationale when answering no to the OP must also believe we cannot know anything about past events either. Any justification for a past event requires induction. I claim this a defect in the rationale.

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There's much debate about whether/why induction suuports rational beliefs. I don't think I've ever heard an argument that shows that induction supports knowledge in the sense meant by skeptics.

Of course your right about past events, skeptics clearly don't believe you can have knowledge of past events (nor present ones for that matter).

You claim there's a defect in the rational, fire away.

chez

[Bork]

I guess I wasnt clear. The defect is simply that if you claim that it is impossible to justify knowledge through induction, which I am guessing all the 'no' answer people are doing then they are commited to saying that we know almost nothing. They dont know that Bush is president, they don't know that that the earth isnt resting on a turtles back, they dont know that dinosaurs existed, or JFK existed, etc. If you define knowledge in that sort of cartesian (must be proven deductively to be true) sense then you are going to know almost nill. Even when you think you have proven something deductively doubts will still creep in about error of inference or memory and with them inductive reasoning creeps in. Induction is not something that can be dismissed if we want to have knowledge beyond things like I am having a monitor like sensation right now, or the a priori necessary truths that were mentioned earlier.