Are All Synthetic Propositions Subject to Doubt?

@hue-man,

truth - 'i live on planet earth' - can be said with reasonable conviction, and is the way we use the word truth on a day to day basis
absolute truth - as yet to be defined, perhaps 'cogito ergo sum', a proposition which is indubitable.

Personally i don't think they should be distinguished from one another, truth is truth, a proposition which it is imopossible to doubt. The truths we say we know are just beliefs which we hold - for good reason - as working hypotheses which enable us to live our lives

---------- Post added 03-03-2010 at 10:14 PM ----------

kennethamy;135606 wrote:

What would make you say that if there is no absolute truth, there is no truth. Would you say that if there are no blue fire trucks, there are no fire trucks?

No, but i would say that if there were no fire trucks, there would be no blue fire trucks.
And this is exactly my point.

@Gracee,

Gracee;135611 wrote:

truth - 'i live on planet earth' - can be said with reasonable conviction, and is the way we use the word truth on a day to day basis
absolute truth - as yet to be defined, perhaps 'cogito ergo sum', a proposition which is indubitable.

Personally i don't think they should be distinguished from one another, truth is truth, a proposition which it is imopossible to doubt. The truths we say we know are just beliefs which we hold - for good reason - as working hypotheses which enable us to live our lives

The propositions that we believe are true, even when we have good reason for them, might be false. But what we know is not false. Therefore, how could it be that what we know are just beliefs we hold are true? I think you must mean that what we think we know may just be what we think are true because we have good reason to think them true. In other words, we believe we know, and we may believe we know for good reason. But it may turn out that our belief that we know is false. That is, of course, right.

@kennethamy,

kennethamy;135616 wrote:

But the propositions that we believe are true, even if we have good reason for them, might be false. But what we know is not false. Therefore, how could it be that what we know are just beliefs we hold are true?

this is the point i have been trying to make all along!
the propositions that we believe are true, even if we have good reason for them, might be false - Exactly, which is why we can doubt things such as 'i exist on planet earth'
And i agree that what we know is not false, which is why we know so little, because there is so little - if anything - we can no without some sort of doubt.

@Gracee,

Gracee;135611 wrote:

truth - 'i live on planet earth' - can be said with reasonable conviction, and is the way we use the word truth on a day to day basis
absolute truth - as yet to be defined, perhaps 'cogito ergo sum', a proposition which is indubitable.

Personally i don't think they should be distinguished from one another, truth is truth, a proposition which it is imopossible to doubt. The truths we say we know are just beliefs which we hold - for good reason - as working hypotheses which enable us to live our lives

---------- Post added 03-03-2010 at 10:14 PM ----------

No, but i would say that if there were no fire trucks, there would be no blue fire trucks.
And this is exactly my point.

That may very well be your point now. But it was not your point then, since to say that there cannot be truth without absolute truth is certainly not the same as saying that there cannot be absolute truth without truth. The first is what you did say, and that is obviously false. But the second is what you say now, and that is quite true. But they are not at all the same.

i wonder why you believe it is impossible to doubt the truth. People have been doing just that throughout history. For example, it was true, as it is now, that the world is round, but, as you know people in the Middle Ages not only found it possible to doubt it, they did doubt it.

@kennethamy,

Gracee;135549 wrote:

Well no, but just because this is the most logical conclusion to come to about the world given the evidence - Russell calls the external world a 'working hypothesis' - does not mean its the right one.
It would be logical for someone who had never experienced water before to assume it would not impede their breathing, just as it is logical for me to conclude that I am alive and I live on planet earth, because I have no reason to believe otherwise. But both are dubitable, there is always the chance that tomorrow I will wake up on another planet and find out I was part of some sort of Matrix like experiment.

Of course it is reasonable of us to conclude that this is not the case, but the point is it is always open to philosophical doubt.

This is what i said to begin with, and you said...

kennethamy;135561 wrote:

But what kind of doubt is philosophical doubt? The American pragmatist, Charles Peirce called it, "sham doubt" , "fake doubt", and "paper doubt", since it has no connection to action. We can philosophically doubt there is a chair at the same time we try to sit on it. Peirce wrote, "We ought not to doubt in philosophy what we do not doubt in our hearts".

And now, i believe, we are in agreement that is is possible to doubt all of our synthetic propositions

@Gracee,

Gracee;135627 wrote:

This is what i said to begin with, and you said...

And now, i believe, we are in agreement that is is possible to doubt all of our synthetic propositions

Oh, it is possible to doubt anything, I guess, just by uttering the words, "I doubt that P is true". As Peirce said, "Some people think that doubting is as easy as lying". I can always utter, "I doubt that P". But the question is whether by doing that I am really doubting that P. Here I am, sitting on the chair, and uttering the word, "I doubt there is a chair I am sitting on". Am I doubting that there is a chair? How are we to tell? What must I do to doubt that I am sitting on a chair? You seem to know, since you seem to believe that it is possible to doubt all our synthetic propositions, so you had better tell me how I can tell whether I have succeeded in doubting that there is a chair I am sitting on. (Now, isn't that a weird question?)

@hue-man,

Can one doubt a hypothesis? Does that even make sense to say? Is not a hypothesis fallible by definition? Then what is the point of doubting what doesn't profess to be the truth to begin with?

But can one doubt 1+1=2? If I say there is lightning and rain because there are storm clouds about, in what sense can my proposition be known or doubted?

For there is a difference between geometric constructions and calculations. Namely, one learns how to use the latter by way of the answers. One is taught how to solve 1+1 by being told the answer is 2.

But suppose we used a different mathematical system, something base 4 or base 20 instead of base 10. Wouldn't the base unit added to itself still be equal to the next sequential unit? At least, if it did not, I would not call the calculus addition.

And so it is with our logical scaffolding; the logic of our language; the limits of propositions.

But surely logic is not a theory. No more than blue is a theory. Or 3.

@Gracee,

Gracee;135574 wrote:

But we cannot forget the rest of the spectrum because in it, somewhere, lies absolute truth, and this is what philosophy was born to find.
No, its not practical, and, no, the search for it may only lead us on pathways of pure abstraction, but it is still truth, in its purest form, undiluted by our humanity, our 'being' - without which we are not, and yet somehow we are something so much more than what we are - and we cannot forget that, no matter how incomprehensible it can become.

This is beautiful. I agree with all of it, and well put. To make another triangle, let's put "truth" which is what sustains us on one lower corner, and Truth that delights and terrifies us in the other. We sit at the top, a collision concept systems, utility-as-truth and unity-beauty-truth. It seems that logic is based on the intuition of the beauty of identity, pure unified being. A beacon summoning Geist to impose its systems on the sensual/emotional chaos.

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Are All Synthetic Propositions Subject to Doubt?

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