Barbers cannot shave themselves.

I maintain that barbers are people who shave people who are in the world.

If they must be shaved, the barbers must visit other barbers. Shaving involves a correspondence between an ideal of cleanliness and the state of affairs on an actual face. Therefore, if a barber tries to shave himself, there is an inherent contradiction.

=========================================

I hope this is clear?

Only if you think A→B does not stand for Not A without B. — Lionino

The "without" reading of A→B does need brackets when written:

Not (A without B)

i.e. ¬(A & ¬B)

I think they are there implicitly in "not A without B" as spoken. So the spoken phrase does clarify the logic of →.

But perhaps they are needed explicitly when the phrase is written. I mean,

(not A) without B

seems a willful misunderstanding. And gives (¬A) & (¬B).

But brackets will prevent that particular misunderstanding.

Yes, the red and white system at least. Unfortunate that it shades in where I was shading out. But it shows how logic uses "not" as a reversal of shading, sending anything in row 2 to row 4 (and vice versa, and also reversing shading within row 3). Whereas ordinary language, while it might do that, might equally well signal a retreat to the very top, leaving all options on the table.

Or (@Leontiskos) it might do something else more elaborate which deserves analysis. Rabbit holes galore, of course. :grin:

If — bongo fury

If.

If

So it's intuitive that

¬(A→B) means A without B. — bongo fury

doesn't follow from

it's intuitive that

A→B means not(A without B). — bongo fury

then it would seem that we don't intuit negation in this case as a photographic negative of the Venn diagram, which is what logic would deliver. In which, i.e., all previous no-go (shaded) areas are declared open for business, and all previous open regions are shaded out. Rather, the intuition is that a (in this case the) previous no-go area is opened up. But nothing closed off. We wish to withdraw or deny an assertion without thereby committing to its negative. Deny it is the case there won't be a sea battle, without claiming there will.

So, not really negation. Not cancelling out the first. Not restoring not(A without B) to A without B.

¬(A→B) appears to suggest, intuitively: maybe A without B, maybe not. No commitment. No information. Tautology. No shading in the Venn diagram. (Whose 4 non-overlapping areas correspond to A & B, A & ¬B, ¬A & B, ¬A & ¬B.)

Leaving it open.

But ¬(A→B), ¬B |= A is invalid. — Banno

Oops.

It's not rocket science.

We use a word to mention a thing.

We use a word in quote marks to mention the word.

I think people can (almost) be forgiven for misunderstanding use and mention in this way. "Mention" in ordinary usage (!) strongly fits with "by the way" or "in passing" ... "Mentioned in dispatches" (... ones that referred more obviously to more central characters.)

And perhaps it's natural to think that any use of a word toward its main function, i.e. towards referring beyond its linguistic context, to actual cats and mats etc, should be understood also to refer in a smaller way, in passing, to the word itself and its linguistic context. And that this subsidiary reference (to syntactic features) might be what the distinction is acknowledging as "mention".

Whereas the distinction as I understand it is the other way round. It insists that we use a word (employ syntax) for the semantic purpose of mentioning, referring to, an object, subjecting it to this or that scrutiny or description. (Or, in less common usage of the same technical distinction, we use a sentence in order to mention a state of affairs.)

Which is slightly at odds with the usual connotation. When you say "scoundrel" do you mean to refer to the man in the dock? Fine. Do you mean to mention the man in the dock? In what oblique connection?? (In ordinary usage of "mention", I mean.)

No excuses. It's a technical distinction, and not rocket science. Just saying.

yet ¬(A→B) and ¬B entail A. — Lionino

To be fair, so does ¬(A→B).

If A does not imply B and [regardless of whether] B is false, can we really infer that A is true? — Lionino

Yes, because it means A without B. Isn't it intuitive that A without B entails A? And isn't it intuitive that A→B means not A without B, i.e. ¬(A ∧ ¬B), so that ¬(A→B) means A without B, and therefore A ∧ ¬B and therefore A?

¬(A→B) means A without B
B is true
Therefore A is true

Does that make intuitive sense to you? — Lionino

Yep. Even if you add the irrelevant and contradictory P2, which is going to make everything true anyway.

What about the following example?
Rain without wetness
Wetness
Therefore rain. — Lionino

Rain without wetness
Wetness
Therefore rain.

Yes. So?

here is the trouble: if ¬(A→B) is true and A is false, B is true. — Lionino

To be fair, if ¬(A→B) is true and A is false, anything is true.

Because, if ¬(A→B) is true, A is true.

Which isn't counter-intuitive, because it's intuitive that

A→B means not(A without B).

So it's intuitive that

¬(A→B) means A without B.

E.g. "An equation being quadratic implies it has real solutions" means not(the equation is quadratic without the equation has real solutions)

So "An equation being quadratic does not imply it has real solutions" means the equation is quadratic without the equation has real solutions.

to posit nested sets — Count Timothy von Icarus

Wouldn't that suggest they are crisp, and a hierarchical tree by set inclusion? But you mean fuzzy and laterally overlapping?

"Clouds" more appropriate?

Unless A is already a contradiction, e.g. defined as C ∧ ~C. Then, regardless of whether A is affirmed or denied, both (A entails B) and (A entails notB) are true. And neither one contradicts the other.

Related...

Do (A entails B) and (A entails notB) contradict each other?

man-made brains-in-a-vat. — Michael

I see.

Surely the problem is the one frequently pointed out, with the word "simulate" being ambiguous between "describe or theoretically model" and "physically replicate or approximate". — bongo fury

You know, map vs replicated territory.

This

high-fidelity ancestor simulations — Michael

being a good example. Amazingly detailed descriptions/theoretical models of ancestors; or physical replicas/approximations of them?

Or something else?

I'm inclined to say than that a thing's effects are signs of it. Directness then should probably be looked at from a phenomenological perspective. — Count Timothy von Icarus

Only if semiotics implies phenomenology.

Photography has almost no reality; it is almost a hundred per cent picture. And painting always has reality: you can touch the paint; it has presence; — perhaps

This corresponds to Scruton's sliding scale of degree of pornographic-ness, if I recall: the greater our interest in what is pictured and the less our interest in the picture for its own sake, the more pornographic. (I think he claimed.)

I once took small photographs and then smeared them with paint. That partly resolved the problem, — perhaps

Interesting. Goodman would probably deny the alleged problem, or see it not as inherent in the medium of photography but rather as a failure to see and interpret the photographs with enough discernment and discrimination. But then he would acknowledge the potential efficacy (just not the necessity) of the proposed solution.

Funny how thus doctoring the photos doesn't necessarily reduce their evidential/trace value. While the apps mentioned by @Jack Cummins probably do?

Anatomical diagrams are a good example here, — Count Timothy von Icarus

Yes, excellent. Especially in pressing Goodman's point that

a thing's properties, "what it is." — Count Timothy von Icarus

is relative to the scientific or other purpose.

Things are phenomenologicaly present in pictures. — Count Timothy von Icarus

But here you're back in the other thread.

Isn't this kind of side-stepping the debate and saying "You have your truth, I have mine" — AmadeusD

Haha, not if @Michael can help it. And good for him.

As he says, and I admitted in the first place, I may not be addressing the usual problem, and certainly not in the usual terms.



Yes, you raise some relevant points about aesthetic notions and doctrines concerning photorealism, which might help expose the subtext I mentioned.

What would a "broken" chain be? — Michael

If conveyance of a physical trace is the criterion, the chain is broken by any link that fails to convey an actual physical trace from one link to another.

An artist's or AI's visual image might be richly informative, and even be considered a true picture of the reported scene or event, but it would break any chain of supposed forensic connection with that scene. Just as a verbal description would break that chain, even if true.

Is seeing my face in a mirror an "unbroken" chain and so "direct" perception of my face? — Michael

If you mean, is your retinal image, or the array of reflectance in the glass, a physical trace of the light reflecting off your face, obviously yes. And the process is direct in the sense of an unbroken chain of conveyance of physical properties and patterns and effects, but indirect in the sense of the properties being transformed and the patterns distorted.

Is watching football on TV an "unbroken" chain and so "direct" perception of a football match? — Michael

I expect most fans of TV football hope that the displayed picture completes an unbroken chain of conveyance of physical traces from the light and sound reflecting off players and scenery at a particular place and time. They would be displeased to learn that the chain began or (restarted) at a different place and time, perhaps in an AI.

So would I. Sometimes a direct, I mean unbroken, connection with reality is important to the epistemic value of audiovisual footage. Although it doesn't guarantee any such value. And it isn't always needed.

I'm not even sure which properties you're claiming to be "presented in and constitutive of the photo". — Michael

Visual ones.

I guess, the same work as "actually"? — bongo fury

But also, the hidden subtext of "forensic" and "physical trace". Which I think Goodman would argue is skewing the debate.

What is the word “directly” doing here? — Michael

I guess, the same work as "actually"?

I'm not defending direct realism on that basis.

Direct and indirect then both apply, in different senses: direct because connecting in an unbroken chain; indirect because involving links and transformations. — bongo fury

Do you mean that some part of the computer running the game would need the detail?
— bongo fury
It would need to simulate the NPC down to the biochemical level. The NPC would need to be conscious to believe anything, and not just appear to believe stuff. — noAxioms

How isn't this as confused as saying "the computer would need to simulate the weather event down to the level of water droplets. The weather event would need to be wet and windy, and not just appear to be wet and windy."

The NPC in the computer game would need that amazing level of detail to actually believe stuff (like the fact that he's not being simulated), and not just appear (to an actual player) to believe stuff. — noAxioms

Do you mean that some part of the computer running the game would need the detail? Then you're talking about an AI, a simulation in the unproblematic sense of a working model: a physical replication or approximation. You might consider subjecting it to an elaborate deception, of course, but then you would be in what you have rightly demarcated as a different set of problems: the VR ones.

Or do you mean that a fictional character described and depicted in the game would need the detail? To actually believe stuff, like the fact that he's not fictional?

A simulation is a running process, not just a map. — noAxioms

A running process isn't just a succession of maps? Does magic happen?

The simulation hypothesis does not suggest that any physical planet (Earth) was created as an approximation of some design/model/real-planet. — noAxioms

Oh good.

It is nothing but a hypothesis of something akin to software being run that computes subsequent states from prior states. — noAxioms

So, a simulation as a description or theoretical model, distinct from any real or imaginary structure satisfying the description. A map, distinct from its territory, real or imagined. Good.

That was very serious. — noAxioms

Gosh. This?

That means that yes, even the paper and pencil method, done to sufficient detail, would simulate a conscious human who would not obviously know he is being simulated. — noAxioms

I have to say this appears to confuse the two senses of "simulate". Otherwise why the fascination with some amazing level of detail? This is generally a sign that the hypothesiser has allowed themselves to confuse map with territory.

A novel or a computer game can perfectly well describe or depict a conscious human that doesn't know he is being imagined, and it can equally well describe or depict a conscious being that does know. Detail is neither here nor there.

... I am not supporting the simulation hypothesis in any form. I'm looking for likely ways to debunk it, ... — noAxioms

Surely the problem is the one frequently pointed out, with the word "simulate" being ambiguous between "describe or theoretically model" and "physically replicate or approximate".

So the question occurs, are you holding this

That means that yes, even the paper and pencil method, done to sufficient detail, would simulate a conscious human who would not obviously know he is being simulated. — noAxioms

up for ridicule, or serious consideration?

I guess I'm intrigued. For example?

To identify the phenomena as being a perfectly attainable goal of science is hardly to debunk the noumena as being a necessarily unattainable goal of science.

If so:

https://en.wikipedia.org/wiki/Unconscious_inference?wprov=sfla1

If not:

https://en.wikipedia.org/wiki/Ecological_psychology?wprov=sfla1

Hence my suggested rewording.

Hence my suggested rewording.

It’s out of Hume. — Jamal

Not with

unperceived existence of what we perceive

Also: https://en.wikipedia.org/wiki/Object_permanence?wprov=sfla1

Perhaps they meant "perception-independent" rather than "unperceived"?

22% of people believe that eating meat is immoral and 88% don't. — Michael

10% are confused.

https://thephilosophyforum.com/discussion/14873/what-could-solve-the-hard-problem-of-consciousness/p1

With or without neuroscience we have the Chinese Room to thank for explaining that a proper semantics (skill in pointing words and other symbols at things in the world, as opposed to merely co-ordinating them with each other) is what makes the difference between a neural network having or not having consciousness. (I.e. between it tending or not tending to think it has a theatre in the head.)

That just leaves unsolved those other, truly hard problems of philosophy that you allude to. Time and so on.

So, the latter?

1. A p-zombie is physically identical to us except that it has no consciousness — Michael

So, physically identical except in respect of its lacking consciousness, possibly physical?

Or, physically identical but different non-physically, in respect of its lacking consciousness, presumed non-physical?

Everybody seems to think we're all the same. It's really hard to grasp that we aren't. — frank

Touche.