I will try to be as specific as possible here: philosophers of mind often specify two levels of existence and/or explanation, the mental and the physical, even if they don't subscribe to dualism. There are understandable issues that might require you to address ontological arguments in those terms if you are arguing for any non-dualist position against a dualist position, but the question I am asking does not concern those or any similar circumstances.

If two philosophers who agree that minds and mind states are fundamentally physical engage in a philosophical discourse that includes the premise that minds are fundamentally physical, is there any good reason they should not posit that minds are one kind of thing, among many other kinds of things, located in the environment external to one's own mind?

Some helpful context: My question is directly inspired by recent readings of Rey, Devitt, Jackendoff, Pietroski, Chomsky, Carruthers, and Fodor. It just seems that no one is willing to simply state what I think is the obvious thing to say.

  • In general it's quite difficult to answer this sort of question (why a school or a thinker doesn't argue for a particular position in a particular way) -- any chance you could provide more context on the problem you're trying to solve? And what have you found out so far?
    – Joseph Weissman
    Aug 19, 2011 at 1:34
  • I am looking at possible justifications for Standard Linguistic Entity realism, meaning realism about words, phones, phonemes, morphemes, etc. The line of argument I am pursuing is structured around locating the proper role of intentionality in a true theory of linguistics. I hope any of that makes sense. Aug 19, 2011 at 2:54
  • I apologize, my response was cut off. What I have found out includes: Rey's folieism offers SLE skepticism in a parallel structure to Chomsky's arguments that there can be no scientific theory of communication, which is also SLE skeptical. Devitt, Jackendoff, and Pietroski are realist (possibly more nominalist for Pietroski). At the center of the whole debate is the role of intentionality in language, especially for the needs of a true theory of linguistics. All parties here are mind realists. Aug 19, 2011 at 3:26
  • Why is grey not considered to be black? minds is undefined, it is a relatively simple concept, that of the self and self's thought, the mind is only as well a part of the external world as the self is part of it. is the self part of an external world? it's a vague topic, and a vague question, like an essay question. Jul 2, 2014 at 19:58

4 Answers 4


Do you simply mean, given that we accept that our own mind is the product of physical processes occurring in our brain, we should also accept that other people have minds much like ours (since they have brains much like ours)?

If that is what you are trying to ask, the answer is a resounding yes. You cannot credibly deny the existence of other minds while accepting the physical basis of your own. (You ought not believe the evidence for physicality if you reject that other minds exist.)

If, in contrast, you're asking whether we can simply assume that others' minds' cognitive narrative causes their actions, given that it seems that way to ourselves, the answer is a resounding no. And the reason is not any trouble with bridging the first-person third-person gap; it is that we cannot be too sure that our own conscious thoughts and decisions are causally necessary! Under certain circumstances, one can predict a "free choice" made by someone seconds in advance of when they make it or are aware of it; there's a decent Wikipedia article summarizing some of the findings.

So the answer seems to be it's complicated, and I expect that this cannot be disentangled by philosophy alone; we also need cognitive science and/or neuroscience to shed more light on what is really going on.

  • This is a genuinely fantastic response. Thank you. Aug 20, 2011 at 20:38
  • I need to get used to the fact that hitting "enter" sends my post. I am not looking at any conscious process which me might call intentionality. I assumed discussion of a subconscious process, possibly even be a higher order thought. Aug 20, 2011 at 21:16
  • @Jaime Ravenet - I am afraid I still don't know exactly what you're looking for, but I'm glad you found my post informative.
    – Rex Kerr
    Aug 21, 2011 at 2:05
  • What I'm looking for is some reason that (some specific) philosophers of mind do not explicitly state that other people's minds can be explanatorily satisfactory and causally efficacious factors of the external environment, when clearly they are. I was concerned that I'd misstepped and missed some important argument, but it looks like I actually was not being specific enough – I hadn't specified conscious vs. unconscious states, and am looking at unconscious ones only. Your post clarified that. Thank you. Aug 22, 2011 at 4:50
  • I think you have hit on one of anomalies that arise for physicalism, such that there is no good answer for your question. But I find the question rather vague and struggle to see exactly what it's asking. . .
    – user20253
    Feb 7, 2019 at 10:18

If two philosophers who agree that minds and mind states are fundamentally physical engage in a philosophical discourse that includes the premise that minds are fundamentally physical, is there any good reason they should not posit that minds are one kind of thing, among many other kinds of things, located in the environment external to one's own mind?

What would it mean for someone to posit that "minds...are external to one's own mind"?

Now, certainly, it is pretty uncontroversial for me to posit that your mind is external to my mind. But it doesn't appear that's what you're after.

A physicalist holds that mental states are reducible to brain activity, but even still, these mental states are not experienced as brain activity.

Put another way: even if one believes that the signified is ultimately reducible to physical states, this does not mean that it is identical to the signifier in its materiality.

  • The question is not whether or not mental phenomena are irriducibly complex, it is about why, if one is a reductionist already, should one not be able to simply claim that the mental lives of others are causally efficacious in an explanatorily satisfactory way as a part of the overall environment external to one's own mind. To out it another way, if physicalism IS true, then why should the discourse continue to discuss only internal mental states when trying to establish the nature of intentional objects. Can't other minds suffice as external causally efficacious objects of our thoughts? Aug 19, 2011 at 17:23
  • I don't see how other minds suffice directly as external causally efficacious objects of our thoughts; it seems to me that (short of telepathy), communication always takes the form of a sign (with a sensible signifier and an intelligible signified). Aug 19, 2011 at 20:12
  • Agreed qua communication. However, this does not explain acquisition of language by infants (barring acquisition be possible in virtue of telepathy). In that case, minds in the environment are specifically causally efficacious, which implies that (under a chomskyan reading) people must be born with the capacity to posit minds, and doing so is one of the principle factors for the unique phenomenon that is the human language faculty. So why does nobody say that? Aug 19, 2011 at 21:55
  • Sorry, I'm afraid I'm not following you. On the problem of "Other Minds" as it applies to non-humans, I'd recommend Simon Glendinning's book "On Being With Others". I don't see how other minds are directly causally efficacious in the case of infants; the usual materiality of the signifier still applies, it seems to me. Aug 20, 2011 at 11:02
  • @Ravenet: i think you also need a genealogical reading. That infants are born with the capacity to posit minds has evolved. Dec 2, 2012 at 17:24

External suggests space. To start with, whether "other minds" take up different spaces is a physical question, one that depends on science, and there's no consensus on what causes consciousness, in any of the sciences. It is safe to assume that consciousness is "located" in the brain, but this is probably not mentioned due to its immense obviousness. We might ask whether two minds take up different space in our everyday world of tables and chairs, but I think that without behaviourism there would be "physical" overlap.

Unless you mean "ontically" external (ontological independence here is pretty trivial): but then we are back asking about ontology in general - which you wanted to sidestep - right?


minds are one kind of thing, among many other kinds of things, located in the environment external to one's own mind?

There is a basic flaw here that assumes 'everything is a thing'. When you try to wedge the mind (or the set of integers, for that matter) into that model, lots of the model of what 'a thing is' falls apart.

To most folks shy of "We are all God" thinkers like Berkeley or Leibniz it is obvious other minds are outside my own mind. If the environment is just 'everything', your position becomes trivially true as a deduction from a non-sequitur -- physicality has nothing to do with it. At the same time, if each mind is a 'thing', as others here have already pointed out, your own mind is hardly external to your own mind, so if this is the notion of minds in general, your own mind is not a mind.

Minds are not that easily separated, anyway. Not only are there many competing thought processes going on at once in your own composite experience, but thought processes are not, by nature, individual.

If the environment isn't just 'everything' then things need some way that they are affixed to it. Usually this is places, but that clearly does not fit our notion of minds. There is clearly 'mind-stuff' that is just kind of nowhere and everywhere, in that it spans minds and does not belong to any individual mind: things that only exist in a composite of minds. Take for instance the English language. Its side-effects, like various sound patterns in the environment, or inkblots on a page are clearly outside the mind.

But the English language itself cannot be said to exist out side the collection of minds. So even if all minds are physical, there are still things that do not exist outside of minds. Likewise 'hope' or 'pi' are things that exist only within minds. They describe patterns of behavior and observations of physical reality, but they cannot be said to exist 'in' or 'as' those things.

So the notion of mind, as a thing has the TARDIS problem, it is bigger on the inside. I can conceive of English, which spans a whole range of minds, including my own. It is inside me, and I am one of the things inside it. Referentiality does not work for 'things in the environment'.

As process-oriented thinking like Daniel Dennett's both points out and pretends not to notice, if the mind is physical, it does not really exist, or at least it is not the sort of thing we think it is.

From this point of view, the mind is a useful concept, but at root it is metaphor for something else too complex for us to discuss easily. And as a metaphor, it immediately becomes one of those things like English or hope, that do not have an independent existence outside a mind.

Then, 'mind' is a metaphor I use to make sense of other people, and ultimately myself. But those metaphors cannot be entirely shared. My exact theories and assumptions about your mind don't exist outside of mine. It is dubious whether they exist inside of mine, to the extent they are not entirely clear.

Flipping the perspective over, all of our minds, as you see them, are not outside your mind. They are models of something that is clearly out here with us, and not in there with you, but the models aren't out here, they are just in there. You can communicate part of them, and you can act on the logic they are made of, but you cannot put them out here in their complete reality.

Even if you decide everything is physical, names and metaphors have to be a different kind of thing, just patterns, physical only in their effects. Then discussing them becomes like trying to hold water in a net. The effects are all there are, and together they specify the thing they make up, but many things have the same effects and many effects have the same cause. The grouping is too fluid to be a thing.

So rejecting idealism is practical in theory, but you are endlessly drawn back to it. You can declare references to be some kind of thing, but that thing has only some kind of statistical existence, and the place where statistics are, is very hard to imagine as having a physics.

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