can we know
what is possible-and impossible-for us to know?
I don’t know whether this applies to your question, but in modal logic, before you can posit that something is not possible, you must first posit that it is possible. Failure to do so is called a “substantive denial of a positive ontological proposition”, and is a famous fallacy.
Puff, puff, give! Puff, puff, give! You’re fuckin’ up the rotation!
I think the OP is describing the whole branch of philosophy called epistemology. I doubt you’ll get a factual answer to this - more like a GD.
I read somewhere in a philosophical text that the only thing we can know for certain is that “something” exists.
The only thing you know for certain is that you exist at the present moment.
And that depends on a very cautious definition of “you” and “present moment.”
Surely this must be taken down a peg to be usable… but to where?
Epistemology it is. Ask five philosophers and get five answers.
Not a factual question, I second the motion to move this to GD.
I’m not real familiar with modal logic, but that seems a little strange. Do you have a reference for that?
I can’t give an answer about ‘know’ and ‘not-know’, but ‘prove’ and ‘not-prove’ is kind of interesting.
Kurt Goedel proved around 1930 that in any sufficiently complex logical system, there will be statements which are true, but cannot be proven true by any means within the rules of that logical system.
It was also proven that we cannot know beforehand whether a given statement is provable or unprovable.
Off to Great Debates.
I know I don’t want to go to work tommorow.
I don’t know why I should go to work tommorow.
I know people will probably notice that I’m not there.
I don’t know if I care.
I don’t know!
…or do I? (heh heh heh he he!)
How do we know something exists? we might be just fooling ourselves.
Tars: If we’re fooling ourselves, we exist.
“I think, therefore I am.” -Renee Descartes. Simple definition, demonstrably true: If you’re thinking, you are.
The basic proof, the only proof, of existence is empirical: Physical proof is required, plain and simple. If a thing has a measurable affect on things around it, it exists. If it does not have any, it doesn’t.
This was covered in some detail (complete with references) in the recent ontological argument thread.
It’s really a much simpler concept than it seems at first glance. You can look at it this way: negation and possibility are two separate operators, ~ and <> respectively. Thus, <>p (p is possible) is implicit in ~<>p (p is not possible).
Another way to look at it is to ask yourself this question: how can you negate something that cannot exist? You are negating something that isn’t there, let alone possible. Therefore, there is nothing for your negation operator to predicate.
To show impossibility, you must posit <>p V ~<>p (p is either possible or not possible), and use a tool of inference (such as modus ponens or modus tolens) to remove <>p.
In a similar vein, you cannot posit necessity without first positing impossibility. The necessity operator, , is merely a composite of ~<>~. Thus, p means ~<>~p (not p is not possible, i.e., p is necessary).
Q: When is a door not a door?
Mark Twain A: When it’s ajar!
Modal Logic A: If ~<>Door, always. If Door, never.
Steve Martin A: Never… no, it was Always… Never open a door when it’s a jar.
Annoying talking car A: [snotty monotone] The door is ajar.
Engywook and Derleth are right. The only thing we can absolutely prove is that we, ourselves, exist – and we can’t prove that to anyone else (As Derleth pointed out, the existence of our thoughts is the proof – we couldn’t wonder about this if we didn’t exist in some form).
We can’t even prove the universe is not a Plato’s-Cave/the Matrix-style illusion.
Everything beyond our existence starts with several basic assumptions. Even science rests on assumption (that the universe is real, that it can be known through the five senses, that the laws of physics will not suddenly stop functioning, etc).
I’m afraid I must disagree.
Why can’t non-existant things think? Seriously, why can’t they?
For that matter, what does it actually mean for something to exist? Again, I’m being serious. It’s a much more difficult question than it would seem at first.
I think that the most difficult questions are those that have obvious (and wrong) answers, because it’s so hard for us to see that the answers are wrong.
“Can we know what is possible and what is impossible for us to know?”
Well now, isn’t that like the dog chasing its tail? First you must establish the parameters of knowing before you can establish the parameters of possible and impossible of knowing.
I sense you are searching for something you can’t understand because you are too busy trying to control it. The problem with control is the limitations it imposes. Why not try trusting -otherwise known as FAITH.
If nothing is impossible and all things are possible then knowing is established and not only knowing in itself but in the knowing of possible and impossible for us.
Which came first the chicken or the egg and does it even matter in the parameters of faith?
You want to see in order to believe. That is control. You are or have allowed yourself to become Doubting Thomas. There is nothing wrong with being a doubting Thomas so long as you know you are in doubt.
The more I know the less I know because everything lives within the parameters of possibilities. This is faith. A word that someone once used to label something unknown.
Hope this helps you if you are still wondering.
Clearly, it was the egg.
Really, heads-up, no joking, it was the egg – that the egg came out of a non-chicken ain’t that surprising to me.
What the rest of that stuff was I have no idea.
I’ve said it before, and will say it again (unless I get hit by a bus) Descartes went too far, he surely meant to say:
I think I think, therefore I think I am.
I would say that first in the list of things that can’t be known is the list of things that can’t be known.
I have to go – there’s a bus I have to catch.
My problem with this is “think” and “I” are very fuzzy ideas. They’re both very hard to explain and require a whole list of other suppositions.
It seems that thought is posited as necessary in the very act of discernment between truth and illusion. But this says very little about what thought is or why a self must exist to think it. It says a lot about our assumptions however.
As I’ve said elsewhere on this board, saying a self is necessary for thought is like saying a creator is necessary for a universe.
There are already some ground rules in the way the OP is phrased. There is a “we” which is probably a set of subjective experiences. There is also the possibility of absolute knowledge about something which supersedes those subjective experience (objective knowledge of a universe). So the very asking of the question and the acceptance of it’s validity, gives us a starting point. I will further make the assumption/clarification that knowledge is a form of awareness experienced by an “I”.
The first thing I can think of that might be impossible to know from these assumptions, is the complete subjective experience of another “I” as this would contradict the subjective/objective relationship of the question (unless I have misunderstood “we”) . The second thing would be the complete objective knowledge of that which excludes “I” since this would also ruin our subjectivity. I would say we cannot know the universe, unless we were the universe, we only know ourselves.