Neuroscientists tell us that time, space, and perceived matter are all constructs of the brain.

As physics is about the exploration of these, is physics really a branch of psychology ? If not, what is the difference ?

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    The experience may be psychological, but the theory about the experience would be separate from that. That would make them different or perhaps I misunderstood your question. – Frank Hubeny Jul 29 '18 at 14:12
  • Well, theories are all constructs too. Constructs on constructs. I know this is probably basic philosophical ground that people versed in idealism and dualism covered in detail. If they have then I hope they step up and explain! – Jimmy Widdle Jul 29 '18 at 14:21
  • If you assume that we are trapped by our experience any science including physics examining our experience. Physics examines now do we experience fundamental forces. But psychology differs from that - it examines how do we have experiences. – rus9384 Jul 29 '18 at 14:39
  • Yes I wasn't sure wether to say psychology or neuroscience. Neuroscience has more objective connotations - deals with matter etc. But neuroscientists are the ones saying space/time and matter are subjective experiences. I'm not sure if or how they avoid solipsism in this. Referring to your comment, isn't it more than an assumption to say we are trapped by our experience ? Would it really be a trap, or does calling it a trap posit a limited subjective viewpoint within an objective whole ? ie - physics tells us what is beyond ourselves and frees us from ourselves. But does it ? – Jimmy Widdle Jul 29 '18 at 14:48
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    Neuroscience, as a field, does not assume that time and space are merely constructs of the brain. Our perceptions of time and space are, but not the time and space itself. Neuroscience, like all science, assumes a physicalist view of reality, not idealist. – Chelonian Jul 29 '18 at 19:31

There's a difference between the ordinary mental representations of space, time and matter everyone has and the mathematical representations of the physicists. The physicists representations are abstract, formal constructs that are posited to explain physical phenomena, while one's mental representation is given in experience, and not posited as an explanation of anything. So it would be a mistake to conflate the two.

Also importantly, the physicist's representations are not an individual's representation, they have collective use: physical theories are not tested against one's subjective perception of positions, but against inter-subjective measurements, generally carried out by teams of scientists, often relying on elaborated measuring apparatus rather than direct perception (distances can be measured with lasers or sonars, durations with all kinds of clocks), converted to numbers (data models) that anyone in principle could check, very often by reading numbers on a computer screen. Neuroscience has nothing to say about these measurements of distances and durations because they do not really depend on anyone's subjective experience of space and time.

Finally, neuroscience cannot really cast sceptical doubt on the results of physics because it relies on them, to some extent: part of neuroscience rests on an understanding of chemistry, which itself rests on an understanding of physics, and the apparatus of neuroscience are based on physical knowledge too. So if neuroscience were to show that the content of physics was an illusion, it would undermine its own basis.

All this does not mean that one cannot be an anti-realist about the content of physics, but it takes more than neuroscience to argue for this.

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  • yes I think that characterises the standard way this is talked about. But when you say "formal constructs that are posited to explain physical phenomena" - isn't that where a conflation takes place - because neuroscience tells us we only have mental phenomena. Wouldn't it be more accurate to say that "formal constructs are posited to explain mental phenomena." That sums up a longer reply which I had to edit. So yeah, I think that's a weak spot in that scenario you paint, which is kind of the standard one we hear. Don't people really conflate mind and matter in that way, not just semantics ? – Jimmy Widdle Jul 29 '18 at 16:44
  • It took me a while but studying what you wrote helped me clarify the issue, good stuff thanks. – Jimmy Widdle Jul 29 '18 at 16:51
  • @JimmyWiddle I think it's a mistake to think of physics as explaining mental phenomena rather than physical phenomena. I understand where the idea comes from: ultimately, all we know comes from some experience. But our everyday experience is messy and unreliable, whereas physics focuses on robust measurements that do not depend on particular individuals and attempts to eliminate subjective variations. This is primarily a collective endeavour, not an individual one (I think this is really where the mistake lies). – Quentin Ruyant Jul 29 '18 at 17:51
  • @JimmyWiddle basically, trusting the results of physics requires trusting that there's some common ground to our various experiences, something that does not depend on particular individuals. If one does not believe in that, for example a solipsist, then s/he can dismiss the whole of physics because all one knows about physics is what one has learned by testimony (in school etc.), not by personal experience. – Quentin Ruyant Jul 29 '18 at 17:57
  • But doesn't neuroscience, as soon as it says we live in a mentally constructed world, say that essentially physical phenomena are mental ones, and all we are trying to do is explain or manipulate what happens in our constructl ? You could postulate some physical matter that plays no part in our mental construct - but we'd never know about it. We also experience collective endeavours in the same mental space. – Jimmy Widdle Jul 29 '18 at 17:58

I would suggest that math is a branch of psychology. From an Intuitionist perspective on math, it is the study of what abstract intuitions most humans naturally share. Those intuitions are clearly ideas, and therefore the province of psychology. The question as to what ideas are mathematical is not about 'absoluteness' or some other way of being true, because ultimately there is nothing real that they actually describe perfectly. The real question is whether they can be naturally evoked in other humans, largely independent of experience, and therefore used as a basis for a shared explanation.

Physics reduces observations to math, but it is not the physics that is psychological, it is the math. Physics does not actually study the concept of space, it studies what things do in space and what space might do in response. Mathematics studies the concept of space as a manifold and provides physics with the geometry that expresses the theory of relativity.

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  • Yes to most of that but the important point is that every psychology textbook will state that the physical world we perceive and play around in is only a model. This is at odds with your depiction of physics, but must be reconciled. – Jimmy Widdle Aug 11 '18 at 11:19
  • No, because it is a shared model, and in the modern world, to combine perspectives, we measure things. So physics, not just physical experience, still reduces it to math on its way to being psychology. – user9166 Aug 11 '18 at 23:23
  • But not forgetting that physical experience is a mental experience, we only experience a model. – Jimmy Widdle Aug 12 '18 at 9:12
  • And that model is not physics. Physics is something built on top of that model, in a way that keeps it from being psychology, because it references data that it has already assumed is perceived by other minds. Math references data that it assumes already exists in other minds without having to be perceived, so it is testing assumptions directly about other minds, not about some intermediate object. – user9166 Aug 13 '18 at 20:59
  • The idea that things in the world are sometimes red is not physics. The idea that red is constituted by a given electromagnetic pattern is. An analogy, perhaps weak: listening to a story isn't reading, reading presumes the story exists in a given form. So does physics. – user9166 Aug 13 '18 at 21:04

The empirical and explanative power of advanced physics is simply incredible, and has even provided "us" with Hiroshima, a man on the moon, etc. You might find some people (philosophers?) that claim these miracles are merely ideal, and say nothing about reality itself. But no-one is saying that we can do these things just by studying the brain. Outside one's Cartesian fantasies, I mean.

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  • "But no-one is saying that we can do these things just by studying the brain. " Indeed. You agree that nobody is ever going to see any actual matter though, yes ? – Jimmy Widdle Jul 31 '18 at 22:25

Our mind categorizes perceptions on two groups:

  • what exists only in our mind, concepts, ideas, etc. That is, subjective perceptions, things that are perceived only by everyone of us.
  • what seems to exist out of our mind, stuff, matter, energy. That is, objective perceptions, things that other persons can perceive, things that several persons can agree about.

What you are saying is that things on the second group are also subjective perceptions, and that can be true: several philosophers state that objectivity is not possible, there is only shared subjectivity.

Anyway, the rules of the first group are fuzzy and irregular. Psychology is the discipline that takes them as the object of study. But it is difficult to assess, due to the high level of subjectivity involved.

On the contrary, the discipline that studies the second group's principles is essentially physics. Physics have shown that several physical behaviors are predictable, regular and stable. This is relatively easier to address, since we can be objective (or at least, share congruent subjectivities) about it.

No, the second group has nothing to do with psychology. Moreover, with philosophy, a set of objects on the first group that allow an intermediate level of objectivity.

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  • Objective is a tricky word to use for the second category as these are still constructions and indeed many if not all do have a different subjective experience of them. I wonder if you know the sort of neuroscience idea that originally made me think about all this - that our perceived world and it's properties are constructed by the brain ? Examples are online - forbes.com/sites/daviddisalvo/2015/10/13/… I just want to know the limits of this, whether it amounts to idealism. – Jimmy Widdle Aug 14 '18 at 13:47
  • @JimmyWiddle Right. The word "objectivity" is considered by some as "shared subjectivity". It is specifically stated "...things that other persons can perceive, things that several persons can agree about". If you and me can agree about something, we are objective: we are referring to the same object, with the same level of truth. Agreement is the key to objectivity and truth. Anyway, as the word is debatable, it's ok to dispense of it: Here, I'm referring to what we agree about. Group 1 is what we don't agree about, and 2 is about we agree about, particularly, physics. – RodolfoAP Aug 15 '18 at 6:59
  • Thanks yes I agree that's a good definition of a certain day-to-day way we use the word objective. People see the word objective in subjective ways, reading all sorts of philosophical assumptions into it. Which makes something of a mess of the subjective/objective dichotomy. I differ on the 'same level of truth', I think it can only approximate (but can approximate closely) except (without assuming everyone is a zombie) for the basic problem of reading other people's minds. We compare our objects with our subjective interpretation of their report of their experience of their objects. – Jimmy Widdle Aug 15 '18 at 7:46

Is it biology that cats fall out of trees at 32 ft/sec/sec? No. Why not? Because there is no biological content. The fact is easily subsumed under a fact from physics. Is it sociological that when you drop acid on a crowd, people cry out in pain? No. Why not? Because the facts of acidity are chemical, and the reaction to pain that causes you to cry out is a matter of individual psychology.

But what do we mean by such assertions. We consider things like acidity to lie within the realm of chemistry, but we consider most facts about protons to lie more properly within physics. And acidity has been part of chemistry since before we knew what protons were. Why did it not spontaneously become physics? Why did chemistry come out of alchemy instead of all this material just vanishing under the umbrella of physics when the theoretical basis of alchemy failed?

One reasonable answer is that the different domains of science handle things that are emergent properties of other domains of science, as elaborated here

By that criterion mere experience is one thing, and psychology studies emergent properties of experience. Your particular sadness is a fact of experience, but it is not a fact of psychology. Only patterns of thought which emerge out of experience can be considered psychological. That watching my dog struggle causes me to be sad qualifies as a psychological observation. That I see red light when there is a red light shining in my eye is hardly psychological phenomenon. That I can see yellow light when you shine a green and a red light in my eye is not even a psychological phenomenon, it is a biological one. And it is not even really a physical one -- it does not fit the normal theory of color in physics.

The idea that I can choose a given wavelength of light that will be perceived as yellow has some physical quality but may not even qualify. The fact that in general different wavelengths of light are perceived as different colors is clearly physics. The breadth of the pattern matters, as it determines where we pull away from the underlying cause and consider an explanation relevant to the question at hand, rather than an overly specific failure to answer it.

The emergence in physics, for physics to be physics, requires separation from individual experience, in a way that the patterns of psychology do not always have to. There can be a psychological fact that applies to only a single individual. But if you had a physical fact that applied only when a given person ran the experiment, it would be rejected as a theory of physics.

To attempt to reduce everything to physics, or to psychology, or even to human experience ignores the reasons we have these concepts. Human experience involves things that are emergent from biology, and things that are emergent from psychology in the same way that biology contains things that are emergent from chemistry and therefore from physics. There is at best a network of loops here, and no most basic set of facts.

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  • "That I see red light when there is a red light shining in my eye is hardly psychological phenomenon. " Comes under psychology though. u.arizona.edu/~bedford/s03outline.htm Awkward fact - mood affects colour vision. Are you talking about the red you see when you're in the pink, or the red you see when you're blue ? – Jimmy Widdle Aug 23 '18 at 18:55
  • It is affected by psychology. If every sensation is psychological because it is affected by our mood, I might have that mood because I am drunk, so that psychology is affected by biochemistry. Is then, everything in your world also biochemistry? Because we can't observe objects falling unless we are beings capable of sensing them fall and sensation is at some point an interior exchange of biochemicals. We don't know that non-biological beings could possibly have a psychology or a physics, so both psychology and physics as we know them must be biochemistry. – user9166 Aug 23 '18 at 22:13

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