Well it seems to me that all we can rely on when it comes to logic is intuition — NotAristotle

That's really sad.

Fine.

That's not the antirealist thesis. The antirealist thesis is that something is true only if it can be demonstrated. You are, again, treating the critic's conclusion as the proponent's claim. — Michael

Ok. This is simply a restatement of the antirealist thesis that something can be true only if it can be demonstrated. Hence, if something can be true then it is possible to know that it is true. Hence, the antirealist knows everything that is true.

Yeah, but ∀p(p→◊Kp)⊢∀p(p→Kp) is valid. It's not enough for antirealists just to say they reject the entailment. Some explanation is needed.

For middle-size antirealism, if something is true then it is possible to know that it is true. This is simply a restatement of the antirealist thesis that something can be true only if it has been demonstrated. But from this it immediately follows that we know every thing there is to be known. That is,

The argument shows that if we assume p → ♢Kp then p → Kp follows. — Michael

Not following that. I'll have another look tomorrow.

And I should clarify, you talk about "all truths being known" in reference to Fitch's paradox, but the relevant claim under consideration is "all truths are knowable", a subtle but important difference. — Michael

Not too sure about that...

(K Paradox) ∀p(p→◊Kp)⊢∀p(p→Kp). — Fitch’s Paradox of Knowability

I don't see any reason to introduce modality. It just adds to the confusion.

SO you want to introduce a new form of validity, that depends not on the explicit structure of the argument but on your intuition. Ok.

If the search function started refusing to process low quality philosophy, most of us here on the forum would be in trouble. — T Clark

But there would be a notable improvement in the quality of search results.

Cheers.

There are two distinct questions we might do well not to compound here. One is if that is a cup. The other is if that is in the dishwasher.

Extensionally, "That is a cup" will be true if and only if that satisfies "...is a cup".

Nothing here about relationships to us. So extensionally,

It does not matter how we specify the set, or how we order its elements, or indeed how many times we count its elements. All that matters are what its elements are. — Open Logic p. 25

I doubt @Michael will disagree with this. He will be aware of Fitch's Paradox, that if the only things that are true are the things that we know to be true, then we know everything.

Now my conclusion is to allow things that are true yet unknown. The cup in the dishwasher is a rough proxy for this, and Michale is right to point out that it is a it too rough. It developed from the usual antirealism hereabouts, that relies on what he has called "phenomenalism".

Again, my contention is that realism provides a better way to talk about the 'medium-size small goods" around us, but that it isn't the only way. This amounts to claiming that it is better to understand that there are true things we do not know, than to claim that we know everything.

That might provide the context for Michael's thought.

That the world has evolved in such-and-such a way does not imply what we ought to do. Saying otherwise is indulging in the Naturalistic Fallacy (the logical one, not the silly idea that what is natural is good).

Within these evolutionary trends, we can find the essence of the ethical principles and moral norms that humanity seeks to identify. — Seeker25

How do you move from how things are to how things ought to be?

I'm not sure how that distinction applies to that premise. — Michael

I'm not sure what the distinction is doing here at all. You introduced it. But presumably, extensionally, X is a cup if and only if X is a cup. Extensionally, we are able to substitute salva veritate. I'm not sure that works for P2. Especially with the vacillation between "seen" and "used as".

I am hunting around for something to tie down your idea.

I explained it quite clearly in that post: — Michael

Not so much, perhaps, since "This has nothing to do with scientific realism" yet " it's perfectly consistent with physicalism and scientific realism". But thanks for clarifying.

P2. For all X, X is a cup only if X is being seen or used as a cup — Michael

I gather this is intensional, as opposed to extensional.

A shame. I was hoping that it would be something to do with the software thinking "A -> not-A, A, ⊨ not-A" invalid.

Still clinging to essentialism. There need be no specified thing that makes you, you. If you lose your memory, who is it who can't recall? The rope is a rope, even though no specific thread runs it's whole length.

Graham Priest has shown non classical logic is compatible with all sorts of theory of truths you find. So we cannot distinguish metaphysical realism or anti realism based on theory of truth via its commitment
to classical or non classical logic. — Sirius

I don't follow this. Non-classical logic is one way to defend anti-realism, but that does not rule out others. So Kripke's theory of truth is arguably classical, in that it only assigns "true" or "false" to any proposition, just not to all of them.

Sure. As I said,

If asked "where is the cup", which answer is to be preferred - "It is in the dishwasher" or "I don't know"? — Banno

This question also applies to . It is rather hard to see how "a cup exists only if there exists some X such that X is being seen or used as a cup" counts as scientific realism. I supose it's quantum?

What is going on here is not a pedantic mismatch between English and some esoteric academic exercise. Rather, there are ambiguities in the English use of "If... then...", "...or..." and various other terms that we must settle in order to examine the structure of our utterances in detail.

Is it worth pointing out, again, that "P→~P" is not a contradiction? If P→~P is true, then P is false.

If that's been said once, it's been said a thousand times... which is not once.

you will cry or I won't punch you — Michael

This uses the inclusive OR which is also not so standard in English.

I can't search in the specific thread "A -> not-A"

In "advanced Search" entering "A -> not-A" in the discussion title does not proved that option in the pop-up. Search results include "A -> not-A", so it's in the searched DB.

I'm not expecting an answer. Just pointing out a curiosity.

But no one speaks like that and no one would make such an inference. — NotAristotle

And yet here we are. Turns out folk do speak like that.

If this thread is not long enough, then it is long enough.

I think it's important to recognise the distinction between intension and extension. — Michael

That strikes me as ad hoc - introducing a needless distinction in order to maintain a position that has been shown errant.

The topic is the truth of "the cup is in the dishwasher", understood extensionally as being about the cup. We might, separately and distinct from this conversation, talk about the suitability of the use of the word "cup" to talk about the cup before us as distinct from and the cup in the dishwasher. Just as we might talk about the suitability of "King Charles" to refer to Camilla's husband if he had been deposed.

The question at hand is not about the suitability of certain descriptions, but the truth of "the cup is in the dishwasher".

Unless you can show that these are somehow the very same question.

but haven't you said that what there is is determined by our words for them? — bert1

"Determined" doesn't sound right. We can name things in different ways, to different ends. But excluding the word "cup" from our vocabulary will not make the cup disappear, except perhaps from our conversation.

Someone who rejects both realism and anti-realism, as I believe Wittgenstein did... — Joshs

Quite. The choice between realism and anti-realism is not a choice of realities, but a choice of language games. If asked "where is the cup", which answer is to be preferred - "It is in the dishwasher" or "I don't know"?

I puzzle as to, if you do not know what a mind is, how will you be able to tell that your definition is correct?

Let's do philosophy instead of polemics. — Leontiskos

I thought you decided not to read my posts. Sure, beliefs have an impact on behaviour. And behaviours have an impact on belief. My point is that how to count genders is a decision, not an observation.

What aspect of what we are aware of will not be an aspect of our own minds? — javra

Not at all a loaded question, that one.

You cant taste oysters without using your mouth, therefore you can't tase oysters as they are in themselves.

Might as well ask what oysters would taste like if we did not have the ability to taste.

So did you change your opinion?

I'll leave you to it. I can't make much of your comment. I'm not sufficiently effete, perhaps.


In a way Wittgenstein subsumed and then expanded Schopenhauer.

Those games can be coherent. Hence their appeal.

Yesterday, upon the stair,
I met a man who wasn't there!
He wasn't there again today,
I wish, I wish he'd go away!

The will is shown in the doing.

Pretty much. Perhaps it's about joining up the stuff we can talk about in a coherent fashion.

Of course, you can show stuff as well as say it.

I don't see as we need the mysticism.

Gender as a case in point. Some folk need there to be only two genders, and so force everything into this or that box. That's an attitude, not an observation. It's taking a list with only two things on it to the shop, not looking at what is on the shelf.

Sure. Folk want to talk about stuff about which they can't say anything. Off-topic, but be my guest.

Kant perhaps would have agreed with Wittgenstein. And if they are right, than we can do away with the so often repeated idea that somehow it is important that we cannot know the nature of the thing in itself. It isn't, it's irrelevant, and takes up far too much time and effort.

I take it that we cannot justify all of our beliefs ad infinitum. — Sirius

This might be right. But it is worth noting that there are things that you know, believe or are certain. Moore made the claim that "Here is a hand". On a forum such as this, we might instead point out that you are now reading this post. Now if you find it difficult to doubt that you are now reading this sentence, then you might also grant things such as that there is a language in which it is written, that someone wrote it, that there are screens and devices and networks linking you to that writer, and so on.

This is not so far form Quine's ontological holism. Once you grant that there are things that it makes no sense to doubt, quite a bit follows.

Kant ran into this problem and there hasn't really been any satisfactory response to it. — Sirius

There is, actually, curtesy of Wittgenstein's beetle in a box argument. We can say nothing about the supposed thing-in-itself, so it cannot have a use in the conversation. It's a useless notion that can be set aside.

Unfortunately folk continue to say quite a bit about it.

SO to your OP. Your account is quite neat. I'll take it that we are here talking about realism as it applies to ontology - to what exists and what doesn't, and not to aesthetics, ethics or mathematics, each of which has it's own version of the realism/anti-realism debate.

Regardless of whether idealism or realism is true, our phenomenological experience of the world would remain unchanged. We would still believe in the existence of the same number of objects. — Sirius

I don't think this is quite right. I'll use an example I've used to the point of tedium here about. When you take your coffee cup and put it in the dishwasher, does it still exist? A realist might say that it either exists or it doesn't, and since we have no reason to think it has ceased to exist, then we can reasonably maintain that it still exists. On this view, there are at least two things in the world, the cup and the dishwasher.

On the other hand, the anti-realist might suppose that since the cup is in the dishwasher we cannot perceive it, and so cannot say for sure if it exists or not. They might conclude that at best we can say that it is neither true nor false that the cup exists. They would conclude that there is at least only one thing, the dishwasher.

These two differ as to how many things they are willing to say there are in the world. But you are quite right that this is about a difference in attitude towards the world, in this case a difference in attitude towards what we might count and what we might not. There is a difference in how the realist and the anti-realist set things out, in what is to count as existing or not exiting.

I would here draw attention to Anscombe again, and to direction of fit. What is to count as an item on our list is something we decide, so our list is more like the one we take shopping than the one we receive at the checkout.

Once more unto the breach, dear friends, once more.

This is a regular topic. What follows is a re-write of stuff from three years ago.

Speaking very roughly, just to get started, realism holds that ...stuff... is independent of what we say about it; anti-realism, that it isn't.

"Stuff", because the content makes a difference.

For instance, if our topic is aesthetics, then aesthetic anti-realism is the view that beauty is in the eyes of the beholder; but an aesthetic realist might hold that beauty and ugly are a part of whatever it is we are beholding.The realist says that something is either beautiful, or it isn't, while the anti-realist perhaps says that being beautiful is an attitude we take towards the item.

A further example. An ethical realist might say good and bad are as much aspects of the world as matter and volume; while an ethical anti-realist might say that no observation of the world will reveal good or bad, because they are not 'out there' to be found.

Stealing blatantly from my Rutledge Encyclopaedia of Philosophy, a realist would generally hold to a set of beliefs that includes: that correspondence to the facts is what makes a statement true; that there may be truths we do not recognise as such, do not believe and do not know; that the Law of excluded middle holds for things in the world; and that the meaning of a sentence may be found by specifying it's truth-conditions.

An ant-realist may in contrast hold that truth is to be understood in sophisticated epistemic terms, perhaps as what a "well-conducted investigation" might lead us to believe; that there can be no unknown truths; that we need include "unknown" as well as true and false in our logical systems; and that the meaning of a sentence is to be found in what it might assert.

Going back to the main point I'd like to make here, one can be a realist in one area and an anti-realistin another. SO for my part, I've argued against typical examples of anti-realism such as pragmatic theory, logical positivism, transcendental idealism and Berkeley's form of idealism. I have however also defended a constructivist view of mathematics, an anti-realist position; and off-handedly rejected realism in ethics and aesthetics.

It is important to note that there is a difference in logic sitting behind the distinction between realism and anti-realism. Realists supose that a proposition is either true or it is false, and that there are no alternatives. Their attitude towards truth is binary. On the other hand, anti-realists are happy to admit at least a third possibility, that a proposition might be neither true nor false, but have some third value. Anti-realism became more prominent towards the end of last century with the development of formal paraconsistent and many-valued logics.

I think a large part of the difference between realism and anti-realism can be explained by making use of Anscombe's notion of direction of fit. This is the difference between the list you take with you to remind yourself of what you want to buy and the list the register produces listing the things you actually purchased. The intent of the first list is to collect the things listed; of the second, to list the things collected. The first seeks to make the world fit the list, the second, to make the list to fit the world. So perhaps anti-realism applies to ethics and aesthetics because we seek to make the world as we say, while realism applies to ontology and epistemology because we seek to make what we say fit the world.

This by way of background.

My apologies. So Davidson took truth as primitive, using it to define meaning, Wittgenstein took use as primitive, using it to talk about truth. Davidson leads to the truth-theoretical approach, Wittgenstein, indirectly, to the proof-theoretical.

That's part of the problem - it was one of the topics I briefly considered for a Doctorate I (thankfully) decided not to pursue. A long time ago.

Roughly, Davidson inverts Tarski, keeping truth constant in order to derive meaning. He hoped to translate natural languages into extension formal language - basically first-order calculus. So truth-theoretical.

Wittgenstein dropped meaning in favour of examining what we are doing. This was loosely linked to introduction rules by Gentzen, roughly that they give logical connectives meaning. Proof-theoretical semantics followed.

But if I had the answer, I'd have that PhD.