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Tom Trelogan
Forum Admin
1368 Posts |
 Posted - Jul 06 2010 : 11:40:20 AM
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| Aaron: you're right that one of these days the sun may not come up. In fact, I think we have excellent grounds for saying that one of these days, the sun won't come up. But from this is doesn't follow that we can't be sure of anything. Can't we be sure of this, that on any day when the sun does come up, the sun does come up? That's another example of an analytic truth. |
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Aaron Mund
Apprentice
37 Posts |
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Tom Trelogan
Forum Admin
1368 Posts |
Posted - Jul 06 2010 : 12:15:41 PM
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Aaron, what you're talking about isn't a case of putting the same statement in different ways. What you're talking about is different statements. And by the way, being right, even being pretty sure you're right, isn't the same thing as being certain.
Furthermore, we don't always have to treat these statements case by case. In many cases, we can treat them class by class. All of the infinitely many statements of the form "If p then p" are true, and we can be absolutely certain that they are. |
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Aaron Mund
Apprentice
37 Posts |
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Tom Trelogan
Forum Admin
1368 Posts |
Posted - Jul 08 2010 : 06:06:39 AM
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Aaron, my guess is that what you meant to write is either this: "We can be certain right now that some statements are true, but will we always be certain that they are true?" or this: "We can be certain that some statements are true right now, but can be be certain that they will always be true?" Which is it? What you actually wrote presents us with a pair of alternatives that don't really make very good sense as alternatives. Word order really matters, you know.
In any case, whatever it is exactly that you meant to write, every statement of the form "If p then p" is just plain necessarily true. It's therefore true now and it will always be true. We can be certain now that it's true, and in the future too, we will always be able to be certain that it's true (unless of course we are bereft of our faculties by the onset of Alzheimer's syndrome or something else similarly debilitating). Similarly for every statement of the form "Either p or not p," for every statement of the form "Not both p and not p," and so on for all the other truths of logic. The truths of logic are really nice examples of necessary truths partly because it's so very easy to see, at least so long as the statements are reasonably simple and we have our wits about us, that they are necessary truths. |
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Richard Mikel
Apprentice
32 Posts |
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John Koban
Apprentice
40 Posts |
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Tom Trelogan
Forum Admin
1368 Posts |
Posted - Jul 11 2010 : 06:24:50 AM
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| John, I'm really unclear what you mean when you say: "I suppose I could see the futurist application if one were looking at something that happened in the past, and was trying to figure out if said truth or plausibility was still true or plausible now." In any case, I most definitely am of the opinion that we cannot know for sure what really happened in the past. I think we we can and do know a great deal about what happened in the past, but certainty--confidence we couldn't possibly be wrong, that there are no conceivable circumstances in which we might turn out only to have thought we knew something about the past when in fact we didn't know it at all--is as elusive here as it is with respect to every purely contingent state of affairs. |
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Andrew Koziuk
Apprentice
34 Posts |
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Cassie Vrooman
Apprentice
32 Posts |
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Cassie Vrooman
Apprentice
32 Posts |
Posted - Jul 11 2010 : 7:49:07 PM
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| Also, I agree with Tom's point concerning "If p, then p," but my question is, how can we know, for certain, that p? So, I guess the question here is this: How can you be certain of anything? |
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Eliott Dimond
Fledgling
19 Posts |
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Katie Contreras
Apprentice
29 Posts |
Posted - Jul 11 2010 : 8:52:24 PM
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Cassie, in response to your question, I myself think that we can't be certain of anything. I don't feel that it is possible to be absolutely certain of anything. I was reading over the recent posts and saw that Tom said that on a day that the sun comes up, it does come up. But, how are we certain that the sun is coming up tomorrow? We aren't. None of us, not in my opinion, can see into the future and tell us all that the sun is for certain coming up tomorrow. Is there a high probability that the sun will come up tomorrow? Yes, but it isn't a 100% certainty. So, I guess what I'm trying to say is that I don't feel that we can ever be 100% certain that something will or will not happen, or that anything is 100% certain; what we can say is that there is a high degree of probability that something will or will not happen, or that it is close to being certain. I just don't feel anything can reach complete certainty. That's all my opinion, though. Others may not agree.
[Lightly edited to enhance readability -TT] |
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Eliott Dimond
Fledgling
19 Posts |
Posted - Jul 11 2010 : 8:53:00 PM
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Richard recently made what I thought was a really good point: "If a statement is true now and untrue later, wouldn't the false statement be an entirely different statement?" If yesterday I said, "Today is Saturday," and it really was Saturday, my statement will always be true. If I was talking today about what I said yesterday, it might seem to no longer be true even though it is. When I said "today" I was referring to the today of then, which is and always will be July 10, 2010, which was a Saturday. This is like saying "Your name is Richard" to Richard and turning to talk to Aaron. Your "you" is now Aaron, not Richard, and if now you said to Aaron "Your name is Richard," that would be false, but that does not change the truth of the statement you made to Richard when you said, "Your name is Richard."
[Lightly edited to enhance readability -TT] |
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Katie Contreras
Apprentice
29 Posts |
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Jenna Stimac
Apprentice
28 Posts |
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Jenna Stimac
Apprentice
28 Posts |
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Cassie Vrooman
Apprentice
32 Posts |
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Aaron Mund
Apprentice
37 Posts |
Posted - Jul 12 2010 : 09:16:06 AM
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quote:
Originally posted by Richard Mikel
My thought on whether or not a statement we know to be true right now might be false later on is similar to what Tom said on July 6th: If a statement is true now and untrue later, wouldn't the false statement be an entirely different statement ? Once it has changed, it is no longer about the state of affairs that made it true, therefore it must have some variable, and must be in some way, a different statement.
I like this question. I would have to contradict you though. I think of older scientific ideas like the earth is flat. That was true then and it is untrue now. The science of the day said that the earth was flat. Today, due to our science, we know that is false, but it was fact then. Or take a criminal case in which a man is proven guilty but then set free on appeal on the grounds of new DNA that proves another guy guilty. There are lots of things that are said to be fact that are reconsidered after more research brings new evidence to light, or that the passage of time proves to be false.
Here are the questions and the answers:
Is the earth flat?
Then "yes"; now "no."
Did John Doe do the crime?
Then "yes"; now "no."
Same question, different answers.
[Lightly edited to enhance readability -TT]
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Katie Contreras
Apprentice
29 Posts |
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Are Philosophers in Touch with Reality?
