You've already shown that you have no idea what you're talking about — Harry Hindu

I know exactly what I'm talking about, thanks.

Now you're contradicting yourself. You said "I don't know" and now you're saying that you do. Which is it? If you know, how do you know? Using AndrewM's qualification for knowledge as having "good evidence", what "good evidence" do you have that you know what propositions are well enough to talk about them?

How can you tell the difference between a proposition and a chicken if you don't know what a proposition is? How are a chicken and a proposition different? You said that you know that, so you should be able to answer that question.

How can you tell the difference between a proposition and a chicken if you don't know what a proposition is? — Harry Hindu

I said I can't give you a definition of "proposition", just as I can't give you a definition of "number". But I know which things are numbers, which things are propositions, and which things are neither.

And I know that 2 + 2 = 4.

And I know that modus tollens is a valid rule of inference.

And I know that chickens are animals.

That's all that matters for this discussion.

It isn't possible to know that p is true and that p is not known to be true, even though there is some p that is true and not known to be true. Therefore, some truths are unknowable. — Michael

Likewise, it isn't possible to eat a chicken and to have it remain uneaten, even though there are some chicken that remain uneaten. Therefore, some chicken cannot be eaten.

Likewise, it isn't possible to eat a chicken and to have it remain uneaten, even though there are some chicken that remain uneaten. Therefore, some chicken cannot be eaten. — Olivier5

That doesn't follow at all.

There are five chickens in a cage. They haven't been eaten but they can all be eaten.

I said I can't give you a definition of "proposition", just as I can't give you a definition of "number". But I know which things are numbers, which things are propositions, and which things are neither.

And I know that 2 + 2 = 4.

And I know that modus tollens is a valid rule of inference.

And I know that chickens are animals.

That's all that matters for this discussion. — Michael

What is a definition if not the suggested, or commonly understood way of using the term? What you're saying is that you don't know how to use the term, proposition, so it doesn't follow that you can know how they relate using formal logic.

What does it mean to know that 2+2=4 - that you've learned how to copy someone else's behavior typing that string of scribbles?

Chickens are animals and propositions are...? You didn't need to get in-depth and metaphysical with your description of a chicken, so why would you think I'd be asking for something different when describing a proposition? Seems like you just want to avoid the question by being purposely obtuse.

It's easy. Propositions and numbers are scribbles that refer to states of affairs. No metaphysics needed.

What is a definition if not the suggested, or commonly understood way of using the term? What you're saying is that you don't know how to use the term, proposition, so it doesn't follow that you can know how they relate using formal logic. — Harry Hindu

Read Wittgenstein’s Philosophical Investigations.

What is life? I know that I’m alive and that a rock isn’t. But there’s no proper understanding of what life is, with over a hundred proposed definitions.

Read Wittgenstein’s Philosophical Investigations. — Michael

As if Wittgenstein is the prophet of propositions. :roll:

Will philosophy ever recover from the damage that Wittgenstein has dealt it?

Read a dictionary.

What is life? I know that I’m alive and that a rock isn’t. But there’s no proper understanding of what life is, with over a hundred proposed definitions. — Michael

Which is to say that we have definitions of life that allow us to distinguish it from things that are not alive. All I'm asking is what those distinctions are. If you can't even answer that simple question then it does not follow that a chicken is not a proposition. A proposition could be anything, which makes your arguments non-sensical.

Philosophy has degenerated into a game of scribbles and utterances. Philosophers scribble and utter like they know what they are doing, but when you ask them what they are doing, they don't know.

To be clear, the difference with that to the knowability paradox is that "p & ~p" is a contradiction - it can never be true. Whereas "p & ~Kp" is not a contradiction. It can be true, but never known to be true.
— Andrew M

Yes, but for the exact same reason than you can't eat an uneaten chicken. Fitch says that one cannot know an unknown truth, because as soon as one knows it, it cease to be an unknown truth. Likewise the Olivier5 chicken paradox states that one cannot eat an uneaten chicken, because as soon as one eats it it ceases to be an uneaten chicken. — Olivier5

That isn't what Fitch says. If the unknown truth is that "there is chicken in the fridge", then it becomes a known truth when you look in the fridge. Then you can eat the uneaten chicken.

But you can never come to know the truth that "there is chicken in the fridge and no-one knows there is". That's unknowable. The philosophical point is that Fitch's proof undermines antirealist theories that define truth in terms of knowability.

Now if you want to progress the analogy, you need a proof that not all chickens are edible. But, even if true, I'm not sure what theory it would undermine. Maybe that everything is a goat.

The alternative, that the Great Goat eats itself, is unpalatable. — Banno

Undoubtedly. But I would further conjecture that the Great Goat is inedible.

Undoubtedly. But I would further conjecture that the Great Goat is inedible. — Andrew M

That's the classical solution, that the Great Goat eats everything but is itself uneaten. Hence the heresy in the argument that:

• Goats eat everything,
• Eating is asymmetric. That is, if A eats B, then B does not eat A.
  Therefore,
• There is at least one non-goat

...which apparently would have one conclude that the Great Goat is not a goat!

Using the convention C for the relation comeditur a , to be consumed, and G for being a goat,

• U(x) ∃(y) (G(y) & C(y,x))
• U(x) U(y) (C(x,y) → ~C(y,x)
  Therefore,
• ∃(x)(Gx)

We don't. But "every possible observation" is not the standard for making knowledge claims or forming beliefs. Good evidence is. If good counter-evidence emerges, then we should change our minds and retract the former claim.
— Andrew M

Which isn't any different than saying knowledge is an interpretation that changes with new evidence - not that you never had it. — Harry Hindu

There isn't an epistemic difference (i.e., either way, one is correct or mistaken about whether it is raining). However there is a semantic difference. With the "knowledge changes" position you can know it is raining when it isn't, on ordinary usage you can't.

What qualifies as good evidence? Isn't there a chance that good counter-evidence emerges later? If yes, then you can never say that you possess knowledge. You would never know that you know or you would know something unknowable. — Harry Hindu

If you want to know whether it is raining then looking out the window provides good evidence. You can say that you know it, but be mistaken, as with any claim. You can also know that you know. That's just how the logic of the usage plays out. As mentioned, the standard for claiming knowledge isn't Cartesian certainty. So its possible to think that you know that you know when you don't.

Yet we asserted that we did know and were wrong, which is good evidence that you could be wrong again, and again, and again - hence no such thing as knowledge unless we define knowledge as an interpretation that changes - not that you never had it. So, using your "good evidence" definition, you have good evidence that you can't ever possess good evidence. Your argument defeats itself. — Harry Hindu

You could be wrong again and again. But that's unlikely for a given case, since you require good evidence for each iteration of the claim. The space of possibilities rapidly diminishes. Consider what it would take to be wrong that the Earth orbits the Sun.

As I pointed out, it is very possible that your good reason or evidence isn't actually a good reason or evidence, and you only find that out after you get good reason or evidence, yet it is very possible that your good reason or evidence isn't actually good reason or evidence, and you only find that out...,etc. It's an infinite regress. — Harry Hindu

It can be a good reason at the time. It may no longer be a good reason in the light of new evidence. Also there need be no infinite regress, as suggested by the orbit example. At some level of evidence you expect to converge on the truth.

No. It is you that assumes a standard of infallibility or Cartesian certainty by saying that "good evidence" is what is needed to possess knowledge. I'm simply asking you to define what that means, if not that "good evidence" is a state of infallibility (knowing the truth). I already pointed out that looking out the window is not good evidence because your brother could be spraying the window with a hose. — Harry Hindu

It is good evidence. If it weren't, then essentially no knowledge claims could ever be made (as Descartes discovered). Yet we do have knowledge. However what constitutes good evidence at one time may no longer be sufficient in the light of new evidence. If you become aware that your brother sprayed the window, then you retract your former claim, since the fact that you looked out the window is no longer a good reason to believe it was raining (though it was a good reason before).

In Fitch's case, the epistemic operator K is usually assumed to be factive and used in the future-tense in standing for "Eventually it will be known that ...", where K's arguments are general propositions p that can refer to any point in time. — sime

knowledge changing over time is no big deal for the verificationist and simply means that one's beliefs are changing as the facts are changing. But this doesn't necessitate contradiction.

For instance, if p is "Novak is Wimbledon Champion", then p today, and hence K p (assuming verificationism). Yet on Sunday it might be the case that ~p and hence K ~ p. But any perceived inconsistency here is merely due to the fact that the sign p is being used twice, namely to indicate both Friday 8th July and Sunday 10th July. — sime

Perhaps I'm just confused by: "K is...used in the future-tense in standing for "Eventually it will be known that ...".

Do you mean anything different to the SEP's definition of K: "it is known by someone at some time that’?

...which apparently would have one conclude that the Great Goat is not a goat! — Banno

Clearly an absurd conclusion. Thus the Great Goat is edible. Which raises the important dilemma of whether all goats partake of the Great Goat, or just the Great Goat itself.

Goats eat everything,
Eating is asymmetric. That is, if A eats B, then B does not eat A.
Therefore,
There is at least one non-goat — Banno

I don't see how the conclusion follows. It seems to follow only that nothing eats goats.

EDIT: ah I see now.

But you can never come to know the truth that "there is chicken in the fridge and no-one knows there is". That's unknowable. The philosophical point is that Fitch's proof undermines antirealist theories that define truth in terms of knowability. — Andrew M

The way I see it, Fitch is a joke of a paradox, and it debunks absolutely nothing. Just like the idea that one cannot eat an uneaten chicken is a joke, and debunks absolutely nothing. So to me, you guys are getting all hung up on a joke.

Have fun. :-)

Clearly an absurd conclusion. — Andrew M

Just another way of saying that it is a misuse of language.

There isn't an epistemic difference (i.e., either way, one is correct or mistaken about whether it is raining). However there is a semantic difference. With the "knowledge changes" position you can know it is raining when it isn't, on ordinary usage you can't. — Andrew M

Yet you did assert that you know when you didn't with ordinary usage. You just know something different now.

If you want to know whether it is raining then looking out the window provides good evidence. You can say that you know it, but be mistaken, as with any claim. You can also know that you know. That's just how the logic of the usage plays out. As mentioned, the standard for claiming knowledge isn't Cartesian certainty. So its possible to think that you know that you know when you don't. — Andrew M

As I already pointed out, you being mistaken is good evidence that you can still be mistaken with any knowledge claim, which is to say that you can never know that you know. So thinking of knowledge as a changing interpretation based on new good evidence resolves the issue. There can be right and wrong interpretations. A wrong interpretation is not no interpretation, just a different one based on the good evidence one had at the time. Given that evidence you had at the time, it would be a valid interpretation. So either we make knowledge a synonym of interpretation or we just omit the word from usage because it would be useless. Using knowledge as a synonym for interpretation is how we use the word in ordinary usage anyway when we take into account how we used the term, "knowledge" in the past as well as now when we say we know but can't know that we know thanks to the good evidence that our interpretations have changed in the past.

The problem of induction is also good evidence that some observation is not good evidence to support an assertion of knowledge in that it seems to call into question observations as justification for forming knowledge.

You could be wrong again and again. But that's unlikely for a given case, since you require good evidence for each iteration of the claim. The space of possibilities rapidly diminishes. Consider what it would take to be wrong that the Earth orbits the Sun. — Andrew M

Which addresses my question that I asked before about how many observations need to be made before we can claim knowledge which you responded:

But "every possible observation" is not the standard for making knowledge claims or forming beliefs. — Andrew M

How would you know that the space of possibilities "rapidly diminishes" without knowing how many observations need to be made? You are claiming to know something that you couldn't possibly know or else you would have made the correct interpretation in the beginning if you knew how many observations you needed to assert knowledge.

Our observations about the movement of the Earth took place on the Earth and out in space. What if we are able to move into another dimension and observe the movement of the Earth - could we say that it still orbits the Sun? "Orbit" might not make any sense when observed from another dimension. We keep trying dislocate ourselves from reality when making observations as if we can make an observation outside of reality. One QM interpretation is that observers have an impact on what they observe, so how do we know that the orbit of the Earth around the Sun is a product of just the Earth and the Sun, or also us as observers.

It can be a good reason at the time. It may no longer be a good reason in the light of new evidence. Also there need be no infinite regress, as suggested by the orbit example. At some level of evidence you expect to converge on the truth. — Andrew M

Which is to say that the interpretation we had was valid given the reasons we had at the time. Our interpretation can change, but that doesn't mean that we never had an interpretation in the past.

It is good evidence. If it weren't, then essentially no knowledge claims could ever be made (as Descartes discovered). Yet we do have knowledge. However what constitutes good evidence at one time may no longer be sufficient in the light of new evidence. If you become aware that your brother sprayed the window, then you retract your former claim, since the fact that you looked out the window is no longer a good reason to believe it was raining (though it was a good reason before). — Andrew M

Which is the same as saying that it was a valid reason for arriving at that interpretation. Knowledge claims can be made if we define knowledge as an interpretation (which I have already shown that the ordinary usage of knowledge is a synonym for interpretation). So we do have interpretations/knowledge. What constitutes good reasons for one interpretation does not qualify as good reasons for a different interpretation. If you become aware of new evidence then you amend your interpretation. This doesn't disqualify that looking out the window is good evidence for interpreting that it is raining. Most of the time it is, and still is even though you were mistaken once before.

Have fun. :-) — Olivier5

Will do!

So thinking of knowledge as a changing interpretation based on new good evidence resolves the issue. There can be right and wrong interpretations. A wrong interpretation is not no interpretation, just a different one based on the good evidence one had at the time. — Harry Hindu

Knowledge refers to the correct interpretations. One can incorrectly interpret something (like the planetary orbits or the weather), but one can't incorrectly know something. As ordinary language philosopher Gilbert Ryle pointed out (bold mine):

The distinction between task verbs and achievement verbs or ‘try’ verbs and ‘got it’ verbs frees us from another theoretical nuisance. It has long been realised that verbs like ‘know’, ‘discover’, ‘solve’, ‘prove’, ‘perceive’, ‘see’ and ‘observe’ (at least in certain standard uses of ‘observe’) are in an important way incapable of being qualified by adverbs like ‘erroneously’ and ‘incorrectly’. ... — The Concept of Mind, p134 - Gilbert Ryle

Which is to say that the interpretation we had was valid given the reasons we had at the time. Our interpretation can change, but that doesn't mean that we never had an interpretation in the past. — Harry Hindu

That's right (though I would use the term justifiable instead of valid). But if your interpretation changes and you believe that you have the correct interpretation now, then you should also believe that you had an incorrect interpretation in the past. But only a correct interpretation can be knowledge, per ordinary usage.

Goats eat everything,
Eating is asymmetric. That is, if A eats B, then B does not eat A.
Therefore,
There is at least one non-goat — Banno


I don't see how the conclusion follows. It seems to follow only that nothing eats goats.

EDIT: ah I see now. — Luke

Ah, but one non-goat won't be sufficient if eating is ongoing.

Deleted

I think all truths are not currently known. Then in the future some truths will be unknowable, they will be lost truths. — Winner568

Something like that, yes. If you make a funny face now, and no one sees you, and you don't even see yourself in the mirror or film yourself, the face you made will be lost to the world (tragically :razz: ). A temporary, transient signal that nobody picked up.

Seen this way, billions of things happen that are never picked up or recorded. What did young George Washington ate for breakfast on February 5, 1742? And the next day, etc.

But are these technically "truths"? It was said by someone here, wiser than me, that truth is a property of statements. Certain statements affirm that x or y is the case, and these statements can be true if indeed x or y is the case, that is, if the statement accurately describes something real, and false if it doesn't.

In the absence of a statement such as: "George Washington ate eggs for breakfast on the morning of February 5, 1742", there would be no truth about it. In the absence of a sentient being questioning what happened, there's no statement being made, no description that can be true or not in comparison to reality. There's only reality. A state of affairs. Things take certain shapes, stuff happen a certain way. A face is made, a young lad eats a breakfast.

This is what is lost: not really truth, technically, but information.

This is what is lost: not really truth, technically, but information. — Olivier5

That said, it is quite possible that our assumption that the past is immutable speaks to nothing more than our own prejudice. Of course we do think that is how things must be...

it is quite possible that our assumption that the past is immutable speaks to nothing more than our own prejudice. — Janus

In his History of Russia and its Empire, Michel Heller states that "Nothing changes faster than the past". He was speaking of historiography: of the way the past is told, of the stories that politicians feed to the people. And in Russia, this national pseudo history changes every decade, to fit today's ideology. So the past changes all the time over there.

Ah, but one non-goat won't be sufficient if eating is ongoing. — Janus

Goats shave eat all those, and only those, that do not eat themselves.

I’m not sure that this is the same, but seems similar.

What about Gödel's incompleteness theorems? Within a given system that we can do math with, there are some propositions that are true but not provable from the axioms of that system. Can we claim to know such propositions which can be handled in only one way - add them to the axioms. Are axioms known? Furthermore, the problem reappears in the new system so constructed?

What about Gettier problems? Justifed, true, beliefs that we have doubts in re claims of knowing 'em!

What about (hyper)skepticism, the position that nothing is knowable in any sense of the word "knowable", argued to based on Agrippa's trilemma, etc.?

Then there's solipsism we have to deal with. The only person I'm certain exists is me! I clearly am not omniscient!