it means the effect already lies in the cause — LFranc

What does this even mean?

But overwhelmingly, lemons smell like lemons.

Seems some folk are perplexed by this. — Banno

Nobody is perplexed by this. It’s the vacuous claim that lemons cause me to experience what lemons cause me to experience.

It has no bearing on anything said by either direct or indirect realists.

How dod you get to that? — Banno

You said that we smell things as they are, which under any reasonable reading is to say that smells are properties of those objects that we are then able to detect.

The existence of organisms with noses has nothing to do with the properties of a lemon, and so if lemons have some property of smell then they have that property of smell even if no organisms have noses.

But lemons don't have smell properties of this kind. It is simply the case that lemons produce chemicals that cause humans (with functioning noses) to have a certain kind of olfactory experience (and likely cause non-human organisms to have a different kind of olfactory experience).

I haven't said the scientific understanding of perception is incorrect. I've said that if the assumption is that perception as such distorts reality then the scientific understanding of perception, which is itself based on perception, cannot be trusted. To trust it and base arguments on it, would on that assumption, be a performative contradiction. — Janus

If perception does not distort reality then the empirical evidence would show us that perception does not distort reality. The empirical evidence does not show us that perception does not distort reality. Therefore, perception distorts reality.

There's no performative contradiction in applying modus tollens.

I've said that if the assumption is that perception as such distorts reality then the scientific understanding of perception, which is itself based on perception, cannot be trusted.

That perception distorts reality isn't the assumption but the conclusion. We don’t start as indirect realists but as scientists and then accept what the empirical evidence tells us about how perception actually works. And that is that colours and tastes and smells are not properties of lemons but are a response to a lemon’s properties. The naive view that projects colours and tastes and smells onto lemons is mistaken.

In the context of this debate, there is no such thing as a direct experience of an external world object, since all such experiences are mediated by phenomenal experience. — hypericin

Direct realists recognize the difference between phenomenal experience and external world objects. So why do they still claim that perception of external world objects is direct?

In an every day context yes, but not in the context of this debate. — hypericin

In the context of this debate, what is required for an experience to be direct? In the context of this debate, is direct experience of an external world object only possible if that external world object is in physical contact with my brain/experience?

we do sometimes see (hear, touch, smell...) things as they are — Banno

So things have a smell even if nothing has a nose? I disagree. There's no such thing as smelling something as it is. It is just the case that some objects produce chemicals that stimulate some sense receptor of some biological organism, causing that organism to have an olfactory experience.

The naive realist view of projecting the properties of that olfactory experience onto that external world object is mistaken.

And the same principle with vision, e.g with colours.

I said nothing of the sort. — hypericin

You said that a direct experience is unmediated. You seemed to be suggesting that if there is some third physical thing in the causal chain between the experience and the external world object then the experience is mediated. The conclusion, then, is that the experience is direct if and only if there is no third physical thing in the causal chain between the experience and the external world object, i.e. that the external world object is in physical contact with the experience (or the brain activity upon which the experience supervenes?).

See my example of the baseball game. — hypericin

So when I'm watching at the stadium I have a direct perception of the game?

The distinction is about mediation. Is the experience mediated, so that it arrives second hand, via a more direct experience? Or is there no intervening layer of experience? — hypericin

So an experience of an external world object is direct if and only if the atoms that constitute that object are physically touching the atoms in my brain that constitute my experience (assuming, for the sake of argument, that experience is reducible to brain activity)? I don't think any direct realist claims that that is the case.

Direct realists claim that we directly experience objects that exist at a distance. So clearly they believe that experience is both mediated and direct, and so "direct" cannot simply mean "unmediated".

This seems like an anti-realist view?

"Blue" is definitional, in terms of wavelengths — AmadeusD

I don’t think that’s right. Particular wavelengths cause most humans in normal lighting conditions to see blue, and so as a matter of convention we might describe those wavelengths as “blue light” but it’s important to recognise that the term “blue” now has two different meanings.

In fact the very claim that two people see the dress to be two different colours requires that colour words (in this context) refer to the quality of the experience and not the wavelength of the light as the wavelength is the same for all of us.

Some colour realists seem to conflate these meanings.

Also there’s the photo of the dress that some see as black and blue and others as white and gold. Any “information” in the experience is influenced by the particulars of our bodies as well as the external stimulus.

How are we to know which parts of our experience provide us with “raw” information about the external world?

Perhaps this is the source of much of the disagreement. The debate is a factual one; about whether we do or do not perceive the world directly. The direct realist position is that we do perceive the world directly; the indirect realist position is that we do not. — Luke

Well, the first step is to explain what it means to experience something directly and what it means to experience something indirectly. Can "direct" and "indirect" be explained without simply being defined as not being the other?

Once that's done, I think it useful to consider senses other than sight. The preoccupation with only visual experiences is an uncritical approach.

So let's take olfactory experience. Do I smell a rose? Or do I smell the geraniol in the air, produced by the oils in a rose's petals? Must it be a case of either/or, or are they just different ways of talking about the same thing?

After that, we should ask if there's such a thing as a correct smell. Perhaps the way a rose smells to me isn't the way a rose smells to you. If there is a difference, must it be that at least one of us is wrong? This leads on to having to ask if, and in what way, smells are properties of roses. Do our noses enable us to experience a rose's "inherent" smell, or does a rose have a smell only because organisms have noses? If the latter then we might then ask if there's a difference between smelling a rose and experiencing a smell caused by a rose.

How would the direct and indirect realist each answer these questions?

And finally, is there something unique about visual experience such that noses and smells are fundamentally different (in the relevant philosophical sense) to eyes and e.g. colours.

It has nothing to do with somebody holding a secret. It has to do with putting a human in the box. — noAxioms

I was just trying to paraphrase the Wikipedia article.

However, unless Wigner is considered in a "privileged position as ultimate observer", the friend's point of view must be regarded as equally valid, and this is where an apparent paradox comes into play: From the point of view of the friend, the measurement result was determined long before Wigner had asked about it, and the state of the physical system has already collapsed. When exactly did the collapse occur? Was it when the friend had finished their measurement, or when the information of its result entered Wigner's consciousness?

The cat is not in a superposition there either — Benkei

It is according to some interpretations of quantum mechanics, e.g. Copenhagen, Von Neumann, and Many-worlds.

which in any case is not a state of being but a consequence of epistomological limitations of knowledge of a given system. — Benkei

I believe this entails local hidden variables, which have been disproven. Superposition isn't just an epistemological limitation but a literal fact.

The cat isn't in a superposition the particle triggering the poison is. The cat is either dead or alive upon opening the box. So the experience of the person is that he was alive in a box if he's still able to answer questions. — Benkei

I think this depends on whether or not something like objective-collapse theory is correct. If it's not then there's no "size limit" to a superposition. If a particle having one spin will result in one macroscopic outcome (the cat is dead) and the particle having another spin will result in another macroscopic outcome (the cat is alive), then the macroscopic outcome is in a superposition until measured.

From here:

According to objective collapse theories, superpositions are destroyed spontaneously (irrespective of external observation) when some objective physical threshold (of time, mass, temperature, irreversibility, etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself" or "the environment observes the cat".

This is Wigner's friend.

Wigner observes John.

John measures a particle spin but doesn't tell Wigner the result.

From Wigner's perspective, is John in a superposition?

I will just say that my question remains unanswered — Philosopher19

I answered it. Neither p nor q make sense. @TonesInDeepFreeze has explained to you in depth that the sentence "A is a member of B in C" is meaningless in set theory.

the universal set is not contradictory in any way. — Philosopher19

This isn't about the universal set. This is about the Russell set. The Russell set is contradictory. It can neither include nor exclude itself without defying its own definition.

There are a number of set theories with a universal set, such as New Foundations and positive set theory.

I was being lazy because this discussion has gone on long enough. Should have been:

S = {S, …}

and

S = {x1, x2, …} where no xn = S

Russell’s paradox:

Assumption: S is the set of all sets that are not members of themselves.

Option 1:

S = {}

S is not a member of itself. But, as per the assumption above, it ought be a member of itself.

Option 2:

S = {S}

S is a member of itself. But, as per the assumption above, it ought not be a member itself.

Neither option 1 nor option 2 work. Therefore, the assumption is a contradiction.

Your p and q make no sense in set theory. Only 3a is meaningful in set theory (although as already mentioned, the “in B” part of the sentence is vacuous). And using that meaning, the set of all sets that don’t contain themselves is a contradiction. Russell proved this.

Whatever you’re trying to argue has nothing to do with Russell’s paradox and nothing to do with set theory.

When a set is a member of another set it is still a set with members of its own.

Given this:

A = {A}
B = {A, 1}

One of these must be true:

1. In B, A isn't a set
2. In B, A is a set with 0 members
3. In B, A is a set with 1 member, and that member is itself
4. In B, A is a set with 1 member, and that member isn't itself
5. In B, A is a set with more than 1 member, one of which is itself
6. In B, A is a set with more than 1 member, none of which is itself

So which of these claims are you making? It must be one of them.

The correct answer is (3):

A = {A}
B = {A, 1} = {{A}, 1}

So how does it follow that L has n-1 members in LL? — Philosopher19

You said that L is a member of itself "in L" but not a member of itself "in LL". So you're saying that L "in L" has one more member (itself) than L "in LL".

Which is nonsense.

If L has $n$ members then L has $n$ members "in L" and L has $n$ members "in LL".

Again, L is not a member of itself in LL (even though it is in LL because it is a member of itself in L). L is only a member of itself in L. — Philosopher19

This is wrong.

1. L is a member of L.
2. L is a member of LL.
3. L is a member of L "in LL"

4. January is a member of Months
5. Months is a member of L
6. January is a member of Months "in L"

Let's make this simple:

A = {A}
B = {A, 1}
C = {{}, 1}

When A is a member of B, is A the empty set?

The answer is no. "In B" the set A contains itself as the only member.

Your position entails that B = C, which is false.

When in fact B = {A, 1} = {{A}, 1}

Here's some JavaScript code to demonstrate:


Can test here. Click "Run" in top left. Bottom right will show "true".

Does L list itself in LL?
Is L a member of itself in LL/not-L? — Philosopher19

What is the difference between asking if L lists itself and asking if L is a member of itself?

I'm not asking how many members does x or y have. So I don't see how your example is relevant to what I asked. — Philosopher19

If L is a member of itself "in L" but not a member of itself "in LL" then L has $n$ members "in L" and $n - 1$ members "in LL".

But this makes no sense. A set is defined by its members.

If L has $n$ members then it has $n$ members "in L" and it has (the same) $n$ members "in LL".

So if L is a member of itself then it is a member of itself "in L" and it is a member of itself "in LL".

L = The list of all lists
LL = The list of all lists that list themselves

1) In which list does L list itself?
2) In which list is L a member of itself?

Can you answer both questions consistently and non-contradictorily? — Philosopher19

Let's consider these four lists:

Months

• January
• February
• March
• April
• May
• June
• July
• August
• September
• October
• November
• December

Planets

• Mercury
• Venus
• Earth
• Mars
• Jupiter
• Saturn
• Uranus
• Neptune

Lists

• Months (January, February, ...)
• Planets (Mercury, Venus, ...)
• Lists (Months, Planets, Lists, Lists that list themselves)
• Lists that list themselves (Lists, (?) Lists that list themselves)

Lists that list themselves

• Lists (Months, Planets, Lists, Lists that list themselves)
• (?) Lists that list themselves (Lists, Lists that list themselves)

Q1. How many members does Months have?
A1. 12

Q2. How many members does Months have when it is a member of Lists?
A2. 12

Q3. How many members does Planets have?
A3. 8

Q4. How many members does Planets have when it is a member of Lists?
A4. 8

Q5. How many members does Lists have?
A5. 4

Q6. How many members does Lists have when it is a member of Lists?
A6. 4

Q7. How many members does Lists have when it is a member of Lists that list themselves?
A7. 4

Q2, Q4, Q6, and Q7 are redundant/confused questions. We only have to consider Q1, Q3, and Q5.

So returning to your questions, they should simply be:

1. Does L list itself?
2. Is L a member of itself?

Assuming that these mean the same thing, the answer to both is yes. L lists itself/is a member of itself.

And so it is also listed by/a member of LL.

So, numbers start at one. — Zolenskify

You're half right.

A subject (you) smells some direct object (smoke, for instance). — NOS4A2

Saying that John smells smoke doesn't explain what it means for John to smell smoke.

The word refers to an external object. If you were to point at that object you would never point internally. The direction towards which your eyes face, in combination with measurable distance between you and that object, never reveal that any of it is internal, and in fact prove the opposite. — NOS4A2

And yet I see and talk about Joe Biden without ever being anywhere near him. The point I am making is that this supposed connection between what I see (and talk about) and the (meta)physics/epistemology of perception is a false one. You're getting stuck on an irrelevancy.

Pain is neither a thing nor a property. It is a noun, sure, but it is without a referent. — NOS4A2

Pain is very real. I don't know what else to say. You're lucky if you've never felt it.

But what it is one is seeing... — NOS4A2

I think the question isn't clear. What does it mean to say that I smell some X?

I agree with a lot of what you said there about the over-concern with the language. But what it is one is seeing, and what object in the world that noun ought to refer too, is important and relevant; and if the indirect realist is unable to state what that is, then the ideas are immediately lacking.

When I see Joe Biden on TV I am seeing Joe Biden on TV, and the term "Joe Biden" refers to the man who is the President of the United States.

I don't see how this addresses the (meta)physics or epistemology of perception. In fact I think it highlights precisely how the attention to how we ordinarily describe perception is misplaced.

A term like “pain” is a sort of folk biology. Maybe one feels a pinched nerve or some other malady that would reveal itself upon closer examination. If true, the latter ought to supersede the former as a more accurate accounting of reality. — NOS4A2

We might disagree over whether or not pain is a physical or non-physical thing, but whatever it is it is real and we feel it, so I don't see how this amounts to folk psychology.

Perhaps physicalism is correct and that pain is reducible to the firing of C-fibres. It still entails that pain isn't a property of the external world object (e.g. fire) that is causally responsible for the firing of those C-fibres. The indirect realist will say the same about tastes and smells and sounds and colours. They're reducible to some bodily function (whether it be in the brain or in the ears or in the eyes), not to some property of the external world objects that are causally responsible for these bodily functions.

Well that is certainly true. That and we often fail to consider how other people are using the terms "direct" and "indirect." — Count Timothy von Icarus

I made much the same point here in another recent discussion.

So to avoid using the terms "direct" and "indirect", my own take is that we have an experience that we describe as seeing an apple, but that the relationship between the experience and the apple isn't of a kind that resolves the epistemological problem of perception (or of a kind that satisfies naive colour realism, as an example).

“Directly acquainted with perceptions” seems a roundabout way of saying we perceive perceptions, which is to assume the initial point. We cannot perceive perceptions any more than we can see sight or observe observations. — NOS4A2

Wording aside, the general idea is that when I put my hand in the fire the pain I feel isn't a property of some external world object but a mental phenomenon caused brain activity (and in turn caused by the nerves in my hand). The same principle holds with tastes and smells and sounds and visual imagery.

Many read far too much into the particulars of English grammar. The fact that we say "I feel pain" and the fact that pain is a feeling and the fact that a simple substitution gives us the non-standard "I feel a feeling" has no philosophical relevance at all. The same for tasting and smelling and hearing and seeing.

The ordinary way of speaking and the (meta)physics/epistemology of perception are two very different things.

What makes them distinct is that in the hallucinatory experience nothing is experienced. — jkop

If nothing is experienced then what is the distinction between having an hallucinatory experience and not having an hallucinatory experience?

It seems to me that you're just playing with words here. Under any normal use of language, things are experienced when we hallucinate (and when we dream); it's just that the experience isn't a consequence of external stimulation of the relevant kind.

some will say that truth and falsity are not applicable judgements for mathematical axioms — Metaphysician Undercover

Which is correct.

What this so-called axiom attempts to do is to introduce truth and falsity into mathematics in the form of correspondence. — Metaphysician Undercover

Maybe for mathematical realism, but then that’s a problem with mathematical realism. Just be a mathematical antirealist and accept that “true” in the context of maths just means something like “follows from the axioms”, with the axioms themselves not being truth-apt.

Referring back to this, it makes no sense to say that the axiom is either true or false. It just is an axiom, and the inference follows.

You’re making a mountain out of nothing.

the point being that we cannot coherently use scientific theories to draw the conclusion that we are most likely BBs — Janus

The consequence of this is that even though we have strong a posteriori evidence for some scientific theory we can rule it out a priori. That seems quite significant.

See the argument here.

Either we know a priori that the universe will not succumb to heat death and expand forever or we know a priori that quantum fluctuations do not happen (or that if they do happen that they cannot form brain-like structures).

Does that seem rational? Or is it just more rational than accepting the possibility that we are most likely Boltzmann brains?

One possible solution is to reject the premise that we ought reason as if we are randomly selected from the set of all observers with experiences like ours (and so that there is some third alternative to SSA and SIA). We accept that heat death and eternal expansion will happen, we accept that quantum fluctuations will form significantly more Boltzmann brains than normal observers have ever existed, but we don't accept that we are most likely one of these Boltzmann brains. Although I'm unsure how to justify this.

What are these models/theories? What predictions do they make? How are they tested? — Patterner

There's the Lambda-CDM model which entails eternal expansion (and eventual heat death), and the energy-time uncertainty principle which entails quantum fluctuations.

Given enough time (which there will be with eternal expansion), quantum fluctuations can generate macroscopic objects, including human-like brains. And given enough time (which there will be with eternal expansion), the number of human-like brains generated from quantum fluctuations will outnumber the number of ordinary human brains that ever existed.

Axiom
Jane is standing between John and Jack, with John on our left and Jack on our right

Inference
The person to the right of John is identical to the person to the left of Jack

The inference is valid even though Jane, John, and Jack are not physical people and are not abstract entities that exist in some Platonic realm.

It seems very straightforward to me.

there is no such thing as an extensional reading of "1+1 = 3-1" — Metaphysician Undercover

There is. The extensional reading of "1 + 1" is the number 2. The extensional reading of "3 - 1" is also the number 2. And the number 2 is identical to the number 2.

Also – and correct me if I'm wrong @TonesInDeepFreeze – but "1 + 1" doesn't actually mean "add 1 to 1". Rather, it means "the number that comes after the number 1". And "3 - 1" means "the number that comes before the number 3".

The number that comes after the number 1 is identical to the number that comes before the number 3.

The only choice is then to reject 2. — Lionino

Which is why I keep saying: either we are most likely Boltzmann brains or our scientific theories are incorrect.

There is an infinite amount of Boltzmann brains though. — Lionino

Well, this ties into my rejection of an infinite past. Even though we can say that if the universe will last forever then the number of Boltzmann brains will increase to infinity, it must be the case that the time from the Big Bang to now is finite, and so that as of now there have been a finite number of brains (whether normal or Boltzmann).

And if your argument for the multiverse follows, the same can be applied for the Boltzmann brains. So Carroll is wrong and we are as likely to be Boltzmann brains with accurate as with inaccurate scientific knowledge. Thoughts? — Lionino

Yes, that would seem to follow if we allow for infinite "parallel" universes (as my reasoning against an infinite past wouldn't hold).

Or perhaps we don't need to reject either heat death or quantum fluctuations, but just the possibility of quantum fluctuations generating a macroscopic object — which is against our scientific theories but not as harshly so. And even if we don't want to do so, by your footnote here, it can be that the time after the heat death is neither infinite or sufficiently large to make it so that there are more Boltzmann brains than ordinary brains. — Lionino

This would be one solution. However, this still entails that we can dismiss some possible empirical fact a priori:

1. If quantum fluctuations can form macroscopic objects then we are almost certainly quantum fluctuations
2. This conclusion is silly/cognitively unstable
3. Therefore quantum fluctuations cannot form macroscopic objects

Of course, it may be true that quantum fluctuations cannot form macroscopic objects, but there's something less-than-rational about the suggestion that we can dismiss such a possibility a priori, especially given that "we are quantum fluctuations" isn't a contradiction.

An a priori but non-necessary truth is peculiar.

Perhaps the simplest solution is to reject scientific realism in favour of instrumentalism. The mathematics of quantum fluctuations are just a useful tool, not something to be taken so literally.

The "laws of nature" are just descriptions of how things behave.

Perhaps you meant to ask why things behave the way they do, or why their behaviour is consistent?

Many still believe it is controversial, and I do too. — Corvus

Many mathematicians?

Many still believe it is controversial, and I do too. No one is saying it is illegal to use it, but just pointing out the existence of the controversy and also reservation on the theory. No one can deny that. — Corvus

This goes back to what I said here:

I wonder if mathematical realists and mathematical antirealists have different views about mathematical infinity. I'm a mathematical antirealist. I have no problem with mathematical infinity. The "existence" of infinite sets does not entail the existence of infinities in nature (whether material or Platonic).

Infinite sets have a use in mathematics. That's all that matters. Reading more into them is a mistake.