I did a volte-face! Check out the OP. It's a bit too long for my liking and I'm sure you won't have the time so I'll summarize it for you here.

Definitions:

To be physical = To be matter or energy or the laws that govern them or some combination of the aforementioned

To be perceivable = Possible to become aware of through the senses or instruments following such procedures as necessary to rule out hallucinations

1. To exist implies To be physical [All things that exist are physical = Physicalism]

2. To be physical implies To be perceivable [all things physical (matter, energy and the laws that govern them) are, for certain, perceivable]

3. To be perceivable implies To be exist [See definition of perceivable]

4. To exist implies To be perceivable.

Suppose 4 is false. If 4 is false then, it's possible for, say, x exists & x is unperceivable

5. x exists & x is unperceivable [statement 4 is false]
6. x is unperceivable [from 5]
7. To be unperceivable implies To be non-physical [from 2]
8. x is unperceivable implies x is non-physical [6 and 7]
9. x is non-physical [6 and 8]
10. x exists [from 5]
Ergo,
11. x exists & x is non-physical [9 and 10]

Statement 11. x exists & x is non-physical is precisely what non-physicalism (some things exist that aren't physical) is. Ergo, the physicalist can't reject statement 4 i.e. for the physicalist who insists that 1. To exist implies To be physical [physicalism], statement 4 can't be false.

Now, the physicalist argument must have the conclusion,

1. To exist implies To be physical [Physicalism]

We know,

4. To exist implies To be perceivable [If the physicalist says this is false then it leads to non-physicalism (see above). So, the physicalist has to say 4 is true]

The physicalist wants to conclude 1. To exist implies To be physical.

The premise required to accomplish the physicalist's goal is,

12. To be perceivable implies To be physical

Then, the following argument takes form,

4. To exist implies To be perceivable
12. To be perceivable implies To be physical [necessary premise to conclude physicalism, 13 below]
Ergo,
13. To exist implies To be physical [from 4 and 12 and is physicalism]

Statements 4, 12, and 13 is the argument for physicalism. It's sound but only if statement 12 is true. Is statement 12 true?

Let's check...

We know,

3. To be perceivable implies To exist

So, now for the physicalist to prove statement 12. To be perceivable implies To be physical, a premise is required. That premise is,

14. To exist implies To be physical

The physicalist's argument that statement 12. To be perceivable implies To be physical is true should look like this,

3. To be perceivable implies To exist
14. To exist implies To be physical [???]
Ergo,
12. To be perceivable implies To be physical [3 and 14]

Take note of the fact that statement 14. To exist implies To be physical is physicalism i.e. physicalism is being presupposed by statement 12. To be perceivable implies To be physical.

Let's rewrite the physicalist argument as it actually is below,

3. To be perceivable implies To exist
4. To exist implies To be perceivable
14. To exist implies To be physical [Necessary premise]
12. To be perceivable implies To be physical [from 3
and 14. Necessary premise to conclude physicalism, 13 below]
Ergo,
13. To exist implies To be physical [from 4 and 12 and is physicalism]

Look at premise 14 and the conclusion 13. They're identical i.e. argument for physicalism is circular - the conclusion is assumed among the premises.

Oops! Too long again. Sorry, it's the best I can do without compromising my argument.

I presume

Circularity is a good thing — unenlightened

Because

Circularity is a good thing — unenlightened

:ok: :up:

Exactly. The rules of chess are the right rules for chess because those are the rules. There can be other rules, but they are the rules for other games.

If you want to do science, construct experiments; if you want to do mathematics construct proofs.

Suppose, for the sake of argument, that we run with some sort of physicalism plus abstract objects.

By some sort of physicalism, I'd start out with a cup of coffee (important), the Moon, a soccer match (Manchester United), ... Of course there's more to it (perhaps mass energy distance/volume duration forces relativistic quantum fields whatever), in a way, but we might start there.

So, where does that (physicalism plus abstracts) then take us?

So, where does that (physicalism plus abstracts) then take us? — jorndoe

To the stars?

Exactly. The rules of chess are the right rules for chess because those are the rules. There can be other rules, but they are the rules for other games.

If you want to do science, construct experiments; if you want to do mathematics construct proofs. — unenlightened

That's odd. Chess is an invention; naturally, everything about it is arbitrary - for instance, the rules are the way they are because the inventor said so.

Physicalism is not like chess. It's a claim about the universe i.e. it has to correspond to reality. Nothing arbitrary about that. It's not that the universe has to conform to our theory (here physicalism), our theory has to conform to the universe. Again, nothing arbitray about that.

You speak as if I can, at will, on my whim and fancy, make the universe anything. Incorrect! Try making gravity disappear by changing the rules, something you must be able to do as per your own admission that the rules can be anything you want them to be (like chess), and see how that works out for you. If you want my advice, don't jump out of windows higher than those on the ground floor.

Physicalism is just a basic common sense notion taken to an extreme... maybe somewhat to it's detriment.

We invented words like real and to exist for the purpose of discerning between ideas/dreams and the world we experience. That's one of the first things moms teach their children, that dreams and ideas aren't real... they can't hurt you.

Circular or not, it still seems like a pretty useful principle to live your life by.

That's odd. Chess is an invention; naturally, everything about it is arbitrary - for instance, the rules are the way they are because the inventor said so.

Physicalism is not like chess. — TheMadFool

That, sir, is the thesis of atheism, that reality is not the way it is because the inventor said so. But it is not clear to me why it would make a difference even if it is true. Chess is real, whether it was invented or evolved, and the rules are the rules, whatever you may think.

That, sir, is the thesis of atheism, that reality is not the way it is because the inventor said so. But it is not clear to me why it would make a difference even if it is true. Chess is real, whether it was invented or evolved, and the rules are the rules, whatever you may think. — unenlightened

You're missing the point. The rules and board setup of chess are indeed arbitrary and the universe could be too whether a creator exists or not. However a theory of the universe is like a particular strategy a player adopts in a game. Just like how chess strategy must be in accordance to the rules, a theory of the universe (physicalism is one such theory) has to be aligned to the rules of the universe. A chess strategy can't be arbitrary and a theory of the universe can't be arbitrary. If you do that i.e. use arbitrary strategies in chess and whimsical theories for the universe, in chess you'll be disqualified and in the universe, it'll be worse as you'll face vigorous, even deadly, opposition at every turn.

You're missing the point. — TheMadFool

Dude first you deny my analogy on spurious grounds, and then you try and play it back at me in garbled form. No thanks.

Dude first you deny my analogy on spurious grounds, and then you try and play it back at me in garbled form. No thanks — unenlightened

Physicalism is a theory about our universe. It's an attempt to describe the universe as accurately as possible. In other words there's pressure for physicalism to correspond to the facts/truths of our universe and that's just another way of saying, physicalism can't be arbitrary - it's not a case of anything goes as you seem to be implying.

I'm afraid that what you're trying to do, and failing to do, is re-inventing or re-defining many of the fundamental terms of philosophy, and then by numbering your propositions, attempting to provide a semblance of logical rigour. You can't casually include 'the laws that govern physical events' in the set of 'physical things', as the ontological status of those 'laws' is an open question. Physics currently postulates things that are *not* perceivable, like dark matter, which are said to comprise a larger percentage of the mass in the universe than is perceivable.

Besides, I would argue that really we don't have a definition of what is 'physical', on the grounds of the many unanswered questions of physics. I think Noam Chomsky says somewhere that we don't have a satisfactory definition of 'a body', and I think that's true. Essentially what most physicalists believe is that what you can see, touch, and objectify, is the criterion of what is real. But I think that quantum physics has undermined that.

Read up on what physicalism actually says, and the counter arguments to it. https://www.princeton.edu/~fraassen/abstract/SciencMat.htm

Regarding the new title: all valid arguments show in the conclusion nothing more than was present in the premises, which seems to be what you mean by "circular" here. That's what validity means.

If you take "physical" to mean "empirical", and "real" to mean "empirical", then of course all and only physical stuff is real.

things that are *not* perceivable, like dark matter — Wayfarer

We can perceive the effects of dark matter, which counts as perceiving dark matter.

Otherwise the only things we ever perceive are photons, since all the interactions of the world with our senses are mediated by photons, and we infer everything else about the world through the patterns in those photons.

Almost everything we perceive, we perceive indirectly, through its effects on other things (which we also perceive through their effects on other things, and so on until you get to the final photons that impart energy to the molecules of our sense-organs), and dark matter is no different in that regard.

A theory is not an argument.

Furthermore, physicalism is not a theory - it's a metaphysic.

We can perceive the effects of dark matter, which counts as perceiving dark matter. — Pfhorrest

Again, don't agree with that. It's a placeholder for a gap in the accounts, but that should be discussed in the thread on that topic.

Otherwise the only things we ever perceive are photons, since all the interactions of the world with our senses are mediated by photons, and we infer everything else about the world through the patterns in those photons. — Pfhorrest

Photons themselves are an element in a causal chain of perception and judgement. We don't perceive photons, in fact it takes an elaborate experimental setup to make them visible, and even then they can manifest as either particles or waves, so their real nature remains moot.

I would argue that really we don't have a definition of what is 'physical — Wayfarer

Therein lies the rub.

Matter, energy, and the laws that govern them are treated as physical. They are known to exist because they're percievable.

How can we define physical.

Since perception through our sense and instruments is the only channel open to the outside world, the definition of physical must be based thereof.

So, it must be that perceivable implies and is implied by physical and this definition of the physical can be decomposed into two statements,

1. Perceivable implies physical
2. Physical implies perceivable

Of these two statements, 2 can't be rejected by the physicalist because it's true that all that's physical (matter, energy, and the laws that govern them) is perceivable

Coming to statement 1, rejecting it means,

3. To be perceivable and To be non-physical

We know that the following statement has to be true,

4. To be perceivable implies To exist [perception here includes all procedures to rule out hallucinations]

Combining 3 and 4, we get,

3. To be perceivable and To be non-physical
4. To be perceivable implies To exist
5. To be perceivable [From 3 Simplifcation]
6. To exist [4, 5 Modus ponens]
7. To be non-physical [3 Simplification]
8. To exist & To be non-physical [6, 7 Conjunction]

Statement 8 is non-physicalism which essentially states that something non-physical exists. This follows from rejecting statement 1 and so the physicalist can't reject statement 1.

What does the physicalist now have to make the case for physicalism viz. concluding that To exist implies To be physical?

1. To be perceivable implies To be physical [can't be rejected by the physicalist]
9. To exist implies To be perceivable

Rejecting statement 9 would mean the following statement is true,

10. To exist and To be unperceivable

Combining 10 with statement 2 we get

2. To be physical implies To be perceivable [remember this can't be false]
10. To exist and To be unperceivable
11. To be unperceivable implies To be non-physical [2 Contraposition]
12. To be unperceivable [10 Simplification]
13. To be non-physical [11, 12 Modus ponens]
14. To exist [10 Simplification]
15. To exist and To be non-physical [13, 14 Conjunction]

Statement 15 is precisely what non-physicalism is viz. something exists and that something is non-physical. Ergo, a physicalist can't reject statement 9. To exist implies To be perceivable.

Now what statements can't be rejected/denied by physicalists?

1. To be perceivable implies To be physical [can't be rejected by the physicalist]
9. To exist implies To be perceivable [can't be rejected by the physicalist]

An argument for physicalism now begins to emerge,

1. To be perceivable implies To be physical
9. To exist implies To be perceivable
Ergo
16. To exist implies To be physical [1, 9 Hypothetical syllogism] [This is physicalism]

However, we know one other statement is true,

4. To be perceivable implies To exist [perception here includes all procedures to rule out hallucinations]

For the moment assume statement 9 is true and doesn't require proof and that statement 1 needs proof

The physicalist argument then made explicit is the following,

1. To be perceivable implies to be physical [4, 17 Hypothetical syllogism]
4. To be perceivable implies To exist
9. To exist implies To be perceivable
17. To exist implies To be physical [necessary to prove statement 1] [This is physicalism]
Ergo,
16. To exist implies To be physical [1, 9 Hypothetical syllogism] [This is physicalism]

As you can see, the conclusion [physicalism 16] is contained in the premises [physicalism 17]

Begging the question OR Circular argument.

Sorry but I can't make it any shorter than this.

Consider the gas laws for an example of physical understanding. They were derived in the first instance from experimental observations and measurements.

The observations were then theorised in the kinetic theory of gases. Certain assumptions about an 'ideal gas' allow the gas laws to be derived mathematically, but with limitations ...

Such a model describes a perfect gas and is a reasonable approximation to a real gas, particularly in the limit of extreme dilution and high temperature. Such a simplified description, however, is not sufficiently precise to account for the behaviour of gases at high densities.

'The ideal gas' is a made up entity to which reality approximates some of the time. This is called "physics". It is of course out of date, and better approximations and more complicated equations have replaced these ideas.

Nevertheless, such is still the nature of physics. Dark matter is a made up entity to explain why galaxies do not fly apart, which they otherwise would if everything else we think we know was right, and yet they don't seem to.

Theoretical models are not reality, they are useful simplifications.

What, then, is physicalism?

Physicalism is the thesis that everything is physical, or as contemporary philosophers sometimes put it, that everything supervenes on the physical. The thesis is usually intended as a metaphysical thesis, parallel to the thesis attributed to the ancient Greek philosopher Thales, that everything is water, or the idealism of the 18th Century philosopher Berkeley, that everything is mental. The general idea is that the nature of the actual world (i.e. the universe and everything in it) conforms to a certain condition, the condition of being physical. Of course, physicalists don't deny that the world might contain many items that at first glance don't seem physical — items of a biological, or psychological, or moral, or social nature. But they insist nevertheless that at the end of the day such items are either physical or supervene on the physical.

https://plato.stanford.edu/entries/physicalism/

My take on it is that physicalism is a form of philosophical monism, that is, there is only one kind of substance (in the philosophical, not everyday, sense) and that substance is matter (or now, matter~energy, as they were discovered to be essentially the same interchangeable through Einstein's famous equation e=mc²).

Perhaps we should clarify what being perceivable means. All perception starts with contact between two physical objects. We see because light bounces off other objects. We hear words through the physical contact of sound.

So what is physical is perceivable, because perception is a process of contact between two physical objects. That's not circular, that's just a description of a physical process.

All perception starts with contact between two physical objects. — Philosophim

But you cannot start there in this thread, because in this thread we are problematising "physical objects". That kind of circularity is the vicious kind.

"Perception starts with physical objects; something is physical if it can be perceived." Nothing has been said, and nothing has been elucidated. Rather, reality has been made dependent on observation, which actually smacks of idealism.

"Perception starts with physical objects; something is physical if it can be perceived." Nothing has been said, and nothing has been elucidated. Rather, reality has been made dependent on observation, which actually smacks of idealism. — unenlightened

No, I'm trying to point out that perception cannot occur without there being a collision of two mediums. Its not an ideal, its simply a fact. You cannot use perception to contradict physicalism, as perception is a physical process. It is a result of physicalism, and not the cause of physicalism. Reality is not dependent upon observation, observation is dependent on reality. And reality, is what is physical.

If you are to counter physicalism, it will have to be something which does not allow the collision of two mediums. And if something can exist that cannot collide with another medium, then it is also beyond perception. An example would be, "nothing". "Nothing" cannot be perceived, only inferred.

Thus we can say reality is composed of the physical, and the nothing. Perhaps there is something else. But you can't use perception, which is a result of a tenant of physicalism called "collision", to contradict physicalism.

I'm trying to point out that perception cannot occur without there being a collision of two mediums. Its not an ideal, its simply a fact. — Philosophim

It's a fact under physicalism. Unsurprisingly, physicalists do not have a problem with physicalism any more than Christians have a problem with Jesus.

reality has been made dependent on observation, which actually smacks of idealism. — unenlightened

Or at least phenomenalism, which I see as a feature, not a bug. Proper physicalism is phenomenalist; proper phenomenalism is physicalist.

The real questions underlying the question of whether physicalism or not are:

is there anything that’s real but completely unobservable?

and

is there anything that’s real to one person but not to another?

Physicalism is the position that says “no” to both of those, or conversely says that there is a universal, non-relative reality, but that it’s entirely phenomenal, non-transcendent.

I'll state the physicalist argument for your consideration.

1. To exist -> To be perceivable [Has to be true for physicalism]
2. To be perceivable -> To exist [True]
3. To exist -> To be physical [??? necessary for 4]
4. To be perceivable -> To be physical [from 2, 3 and necessary for 5]
Ergo,
5. To exist -> To be physical [Physicalism] — TheMadFool

Trouble is, this is not the argument for physicalism. I've seen something like this before, again in a proof of circularity in physicalism. Did you perchance write a paper on this?

The physical (as in physicalism, as in the physical sciences) is that which is empirically verifiable in principle by definition. There is no difference between (1) and (5) without making the definition of 'physical' up for grabs, so the circularity is being introduced by hand.

The usual argument I'm aware of is reductio ad absurdum. Physical objects are those with purely physical properties, such as mass, charge, position, momentum, etc. Physical properties are couplings between objects. A change in the momentum of one body is brought about by the change in the momentum of another. The charge of one body that _causes_ the properties of another body to change is precisely the same property that allows the first body to change due to the second. Such correlated changes in the (directly or indirectly) observable properties of bodies are what physics is about.

We can consider additional, non-physical properties and bodies comprised purely or partly of them, but we have to understand what that means. A non-physical cause might have a physical effect, such as a non-materialist idea of free will leading to physical movement. A physical cause might have some non-physical effect, such as perhaps a creationist might think of emotional responses to physical stimuli as being an effect on the soul. Finally a non-physical cause might have a non-physical effect.

The first two are empirically eliminated, since either would breach conservation laws. E.g. if a non-physical cause could have a physical effect such as movement, physics wouldn't work at all: momentum and energy would not appear to be conserved. Likewise if a physical cause had non-physical effects. In addition, it's a contradiction. Supposing that a non-physical property could couple to a physical property such that the non-physical thing having the former could cause the physical thing to change, e.g. the proposed non-physical mind has the property of being able to induce the physical brain to send a signal to the left leg to make it move. What then makes that property non-physical? It is not unobservable any more than the curvature of spacetime or the colour charge of quarks: we can infer its presence from its effects. Such a non-physical property would be physical by virtue of what it does.

Which leaves non-physical causes of non-physical effects, neither of which can be observed directly or indirectly, subjectively or objectively since they are, by definition, purely unobservable things. We cannot speak of their properties since we have no insight into them. We cannot verify their existence. These are dismissed as redundancies.

The same goes for non-physical properties of otherwise physical things. If it is their physical properties that couple to the properties of purely physical things, then either the non-physical properties couple to those, making them physical, or else the non-physical properties do nothing at all, in which case why postulate them?

A physical cause might have some non-physical effect, such as perhaps a creationist might think of emotional responses to physical stimuli as being an effect on the soul. — Kenosha Kid

So to believe in the soul is to be creationist?

So to believe in the soul is to be creationist? — Wayfarer

That is not a logical inference.

So to believe in the soul is to be creationist? — Wayfarer

Are there Hindu creationists?

That is not a logical inference. — Kenosha Kid

It appeared to be what you had written.

The physical (as in physicalism, as in the physical sciences) is that which is empirically verifiable in principle by definition. — Kenosha Kid

Physicalism and empiricism are different principles. Besides there are vast areas of conjecture in current physics which are beyond empircal verification in principle, such as the multiverse conjecture and string theory.

A non-physical cause might have a physical effect, such as a non-materialist idea of free will leading to physical movement. — Kenosha Kid

Leave aside telekenesis. What about plain old psycho-somatic effects? Patients get sick, and are also sometimes cured, by what they believe. Placebos have a measurable affect on patients, even though they're physically inert. In those cases a psychological (mental) cause has a bodily (physical) effect.

Are there Hindu creationists? — Marchesk

Probably. There are sufficient numbers of Hindus to include representatives of almost everything although it's hard to see how that's relevant to the OP.

I couldn't emphasize how important it is that you watch this film, it will clarify doubts you may have on the topic. There are also some interesting articles.

In those cases a psychological (mental) cause has a bodily (physical) effect. — Wayfarer

If what you call "psychological causes" are themselves physical, neuronal processes then your argument fails, and the mystery (or at least the one you're promoting) dissolves. In other words, your argument assumes what it purports to demonstrate.