The Stanford Encyclopedia of Philosophy article called "Zombies" https://plato.stanford.edu/entries/zombies/ makes no mention of an assumption that seems to be hidden in the famous philosophical zombie question. Using the search text function of my browser I looked at every instance of the string "assum" so as to examine every time the word "assume" or "assumption" or "assuming" or "assumed" in the entire long article.

Likewise, searching the article for "circ" to check for any mention of possible circularity or arguing in a circle turned up nothing relevant. Ditto for "beg".

The assumption I am referring to is that normal human beings are not philosophical zombies, in other words, the assumption is that normal humans have qualia and conciousness.

Here's the beginning of the SEP article: " Zombies in philosophy are imaginary creatures designed to illuminate problems about consciousness and its relation to the physical world. Unlike the ones in films or witchcraft, they are exactly like us in all physical respects but without conscious experiences: by definition there is ‘nothing it is like’ to be a zombie. Yet zombies behave just like us, and some even spend a lot of time discussing consciousness.

Few people, if any, think zombies actually exist. But many hold they are at least conceivable, and some that they are possible. It seems that if zombies really are possible, then physicalism is false and some kind of dualism is true."

There seems to be an implicit assumption that ordinary humans have consciousness and qualia. It's just taken to be a fact that can be used without acknowledgement.

I hope this isn't a digression, but it seems relevant to me that it says, "Few people, if any, think zombies actually exist." "if any". What? Dan Dennett said we are all zombies. There are clearly some people who think zombies exist, so this is flat out wrong. And that's not to mention the superstitious people all over the world who believe in walking corpses.

Dan Dennett famously said that we are all philosophical zombies. Wikipedia says in its article called "Philosophical zombies", "Some physicalists like Daniel Dennett argue that philosophical zombies are logically incoherent and thus impossible, or that all humans are philosophical zombies;" https://en.wikipedia.org/wiki/Philosophical_zombie

Turning now to the way the Wikipedia article handles the zombie idea, the idea is introduced with the following paragraph: "A philosophical zombie argument is a philosophical thought experiment which conceptualizes a hypothetical being that is physically identical to and indistinguishable from a normal person, but does not have conscious experience. [1] For example, if a philosophical zombie were poked with a sharp object, it would not inwardly feel any pain, yet it would outwardly behave exactly as if it did feel pain, including verbally expressing pain. A philosophical zombie would not possess consciousness acting only on instinctual programing, and actions of which respond to the stimuli of the world around them." No mention of the assumption that ordinary humans have consciousness and qualia.

Instead of stating in the intro of the Wikipedia article when defining the zombie idea the assumption that normal humans have consciousness and qualia, the assumption is mentioned in passing and in parentheses in a sentence buried (I found it with an automated seach for the string "assum") deep in the body of the article: "When a distinction is made in one's mind between a hypothetical zombie and oneself (assumed not to be a zombie), the hypothetical zombie, being a subset of the concept of oneself, must entail a deficit in observables (cognitive systems), a "seductive error"[4] contradicting the original definition of a zombie. " The extremely complex verbiage (I, for one, cannot make head or tail of it) makes it very hard to even figure who it is allegedly assumed by that oneself is not a zombie. It is far from being a clear statement that the zombie idea contains the assumption that ordinary humans have consciousness and qualia. So, although better than the SEP article, which doesn't even mention the assumption, the Wikipedia article is only a little better, and is guilty of not mentioning the assumption when defining the idea of a zombie at the outset.

What about Chalmers himself? His website introduces the zombie idea like this https://consc.net/zombies-on-the-web/: "Zombies are hypothetical creatures of the sort that philosophers have been known to cherish. A zombie is physically identical to a normal human being, but completely lacks conscious experience. Zombies look and behave like the conscious beings that we know and love, but "all is dark inside." There is nothing it is like to be a zombie.

Varieties of zombies

There are actually three different kinds of zombies. All of them are like humans in some ways, and all of them are lacking something crucial (something different in each case)."

No acknowledgement by Chalmers that it is assumed that ordinary humans have consciousness and qualia, nor that anyone doubts this.

Later on in Chalmer's article it says, "It can be used as a way of illustrating the "hard problem" of consciousness: why do physical processes give rise to conscious experience? This question might equally be phrased as "why aren’t we zombies?". If any account of physical processes would apply equally well to a zombie world , it is hard to see how such an account can explain the existence of consciousness in our world." "Why aren't we zombies?" There's the assumption that we aren't, but it's not acknowledged.

And then, "It can be used to raise questions about the function of consciousness: why did evolution bother to produce us if zombies would have survived and reproduced just as well? (As e.g. Flanagan and Polger have argued.)"

He seems to me to be assuming what he has set out to prove.

Interestingly, Chalmers does subtly acknowledge (IMHO, by placing the words "do more work" in quotes) that the existence of God is moot in this paragraph: "And it can even be used to argue against materialism. If there is a possible world which is just like this one except that it contains zombies, then that seems to imply that the existence of consciousness is a further, nonphysical fact about our world. To put it metaphorically, even after determining the physical facts about our world, God had to "do more work" to ensure that we weren’t zombies." But he doesn't let the reader know that the there are more than one school's of thought that regard "consciousness" and "qualia" as moot (consciousness illusionism (Keith Frankish) https://www.youtube.com/watch?v=Y2n-s6C1iYQ&list=PLhgvALi0LQGXIA7cKNmGNTiQ7dpS-7dLw and eliminative materialism https://plato.stanford.edu/Archives/Win2004/entries/materialism-eliminative/ to mention two that I know of, and one could arguably add heterophenomenology, behaviorism, and logical positivism).

And searching for "assum", "circ", and "beg" yielded nothing in the Chalmers article.

Allow me to make an analogous "free-will zombie" argument/thought experiment. "A free-will zombie is just like a normal human being except that it lacks free will." It's obvious that I have failed to acknowledge that whether we have free will is moot. The philosophical zombie idea is introduce just like this, but no one seems to notice the failure to acknowledge that it is moot whether we have consciousness. Philosophical zombies are "consciousness zombies" which are analogous to my "free-will zombies". It seems that the problem is that people are generally aware that some doubt that humans have free will, but they are not aware that some doubt that humans have consciousness (in the qualia-having sense).

So my question is, does the philosophical zombies question/idea contain a hidden assumption?

In light of this Meta answer: https://philosophy.meta.stackexchange.com/a/5470/58715 I have prefixed "(Why)" to the title of this question and have added to the body of the question, under the dashed line, some text.

I have convinced myself that there is no doubt that there is a hidden assumption in every presentation of the zombie question that I've looked at, including that of SEP, Wikipedia, and Chalmers' own website and so I have decided to focus the scope of the question on what seems a more interesting question, which is "Why is the assumption inherent in the zombie question hidden?"

I might as well add here another analogous question that shows how outrageous it is that the assumption in not acknowledged. Wikipedia, to its credit was the best out of the three in this regard, as you can read above, but even there the acknowledgement was buried in the body of the long article.

Imagine that I asked, "Is it conceivable that in our universe there could exist a philosophical zombie cat, meaning a cat that is the same in every respect as a normal cat, down to the last atom, except that it has no consciousness. It is dark inside. There is nothing it is like to be that cat." There's an assumption that ordinary cats are conscious. It would be interesting to put this question to people and see whether they notice or object to assumption hidden in it. It would be interesting to try out the zombie idea switching out humans for chimps, dogs, cats, crocodiles, snakes, sharks, and so on right down to bacteria and maybe viruses and even DNA molecules.

In the original version of this question I posited switching out free will for consciousness in the zombie question. This tactic could be combined with substitution of dogs and so on, to make the question "Could a kind of dog be conceived of that is the same as a normal dog except that it doesn't have free will?"

It's hard to believe Chalmers and SEP haven't heard about illusionism (or "consciousness illusionism" if you want to distinguish it from free-will illusionism which is a rarely-heard term for an unrelated and much older and well-known idea that says free will is an illusion i.e. does not exist despite the unshakeable subjective impression that it does.)

So my question is, does the philosophical zombies question/idea contain a hidden assumption and why (if/because it does) is this assumption (that normal humans are conscious and have qualia) not explicitly stated when the zombie question is asked?

  • How does the mere act of discussing something constitute an assumption that the thing being discussed doesn't exist? Apr 14, 2023 at 17:42
  • @DavidGudeman Where did I say or imply that it does? Apr 14, 2023 at 17:45
  • No the idea doesn't contain that assumption going off what you wrote. If that quote is attributable to Dennett, "Some physicalists like Daniel Dennett argue that philosophical zombies are logically incoherent and thus impossible, or that all humans are philosophical zombies", the emphasized part (me), shows a qualia denier, Dennett, knows what it means to speak of qualia regardless. To say zombies brings in the notion of qualia. Since Dennett denies qualia and can speak about the ideas of zombies and qualia as he did, the idea of zombies doesn't require such an assumption.
    – J Kusin
    Apr 14, 2023 at 17:57
  • @JKusin You wrote, "Since Dennett denies qualia and can speak about the ideas of zombies and qualia as he did, the idea of zombies doesn't require such an assumption." Please state explicitly the assumption that you are referring to, so that I can understand and respond. Apr 14, 2023 at 18:08
  • "an assumption that seems to be hidden in the famous philosophical zombie question". There is nothing implied by "the famous philosophical zombie question" than a discussion of the possibility. A particular discussion of the question might make the assumption you mention, but you are pointing to all discussions in general. Apr 14, 2023 at 18:26

8 Answers 8


You say that the first para of the SEP article include the words "[Zombies] are exactly like us in all physical respects but without conscious experiences". Clearly the 'but' implies that we (ie humans) have conscious experiences. If you consider that to be a hidden assumption, so be it. Others might consider it a matter of fact.

Claims of hidden assumptions can be made in relation to almost anything. Suppose I asked you to imagine a planet that was locally identical in every respect to Earth, except that it was flat. Would you say there was a hidden assumption that the Earth was not flat? If I asked you to imagine a white Volkswagen Beetle that was identical to any other white Volkswagen Beetle except that it had a mind of its own, would you say there was a hidden assumption that white Volkswagen Beetles don't have minds of their own? I am as utterly convinced about my having conscious experience as I am about the Earth not being flat and Herbie being a fiction, so to me there is no hidden assumption in the SEP article. If you are convinced that you are a zombie, then to you the SEP article might seem utterly bigoted nonsense that begs a very important question.

  • I hesitated to edit my question after you had posted an answer, and did so only after reading this Meta answer: philosophy.meta.stackexchange.com/a/5470/58715. Apologies for any inconvenience caused. Apr 16, 2023 at 7:37
  • I'm not convinced that I am philosophical zombie, but I do have genuine doubts about the matter, as do many others including Dan Dennett (assuming he isn't convinced that he is zombie). "Bigoted" seems a bit strong. Ignorant and/or (self)deceptive seems possible and reasonable. Apr 16, 2023 at 7:40
  • 1
    @MatthewChristopherBartsh it was very kind of you to let me know. And I must also thank you for posting the link to the series of lectures on Youtube, which I have been playing with great interest. It seems to me that there is a distinction between the zombies of Chalmers and Denote. I will reply again when I have finished the lectures. All the best! Apr 16, 2023 at 8:36
  • All the best to, you, too. I watched some parts of the series on speed 1.5 because he does sometimes speak very slowly indeed. Enjoy! Apr 16, 2023 at 9:49
  • The flat earth theory is intuitive, ancient, and primitive, and doubters were ridiculed and worse, but the doubters prevailed and the theory (or belief or assumption of a flat earth) was proved false. It seems that the unproved and nearly always unquestioned and unreflecting belief in qualia is analogous to flat earth belief. In light of this, it seems to make more sense to reword your remark as follows: "Suppose I asked you to imagine a planet that was locally identical in every respect to Earth, except that it was round. Would you say there was a hidden assumption that the Earth was flat?" Apr 17, 2023 at 9:38

So my question is, does the philosophical zombies question/idea contain a hidden assumption and why (if/because it does) is this assumption (that normal humans are conscious and have qualia) not explicitly stated when the zombie question is asked?

Yes. All questions do. And all answers. And all arguments. This was noted and explicated on by Quine with his notion of confirmation (epistemological) holism in his exploration of theory ladenness which has a perceptual and semantic aspect. While the discussion is had among philosophers of science, the notion that there is a holistic aspect to epistemological thinking permeates contemporary philosophy of language with its focus on expressiveness, productiveness, and compositionality. Semantic epistemological holism is the thesis in its moderate form that propositions are only meaningful within the context of the situation. Thus, there is the larger body of text (endophora), by examining references outside of language (deixis), refering to meaning not specifically encoded (implicature), and paying attention to the intentions of language (Sprachspiel). This is what Quine may have been signalling when discussing the notions of web of belief. Every argument made has hidden assumptions, because no one spells out one's worldview before crafting language. The question becomes is it necessary to include the assumption? The one you point to doesn't seem necessary since it is almost universally presumed to be true.

So, is it unstated that human beings have consciousness and experience qualia. Yes. Is this surprising? No. The objective of philosophical zombies argument is to challenge that intuition and force the thinker to deal with the notion that other human beings might not have minds. This isn't isn't revolutionary. It's solipsism in a modern language.

In Ancient Greece, three important epistemological problems unfolded themselves. The first is the question of the existence of knowledge. Why shouldn't we be radical skeptics? The second is the question of the difference between appearance and actuality. Should we accept naive realism? And the third is how do we know other minds exist if we only can introspect our own? This is the problem of solipsism. Needless to say, most modern thinkers move beyond Pyrrhonism, naive realism, and solipsism and accept knowledge exists, accept representational theories of mind, and accept that we may infer other minds exist. Thus, the problem of the philosophical zombie is an attempt to push back on the last two to accentuate that there isn't consensus on mind-body duality, which is another problem that seems to arise.

Why do people hide the assumption contained in the philosophical zombies question/idea?

So, the assumption is not hidden. It's just so obvious it isn't mentioned in these sorts of conversation, because the notion that humans have consciousness is powerfully intuitive. According to a naturalistic approach to epistemology, the reason for that is straight forward: human beings are genetically enabled to generate theories of mind and to use collective intentionality. Like breathing and using our opposable thumb, it's simply natural to understand and collaborate with other people; in fact, it is thought by some researchers that autism is a condition that is caused in part by neurodiversity leading to mind-blindness. I suspect most psychiatrists would consider radical solipsism, an unfettered inability to believe in other minds, a presentation of a symptom of a mental disorder. People who sincerely believe they are Jesus, or Elvis, or aliens, or the only person really alive behave in ways that confirm it, and lead to social situations that support therapy and institutionalization in the extreme.

The sort of people who engage in vibrant debate about mind-body duality, reducing the mental to the physical, and can discuss intelligently eliminative materialism and subjective idealism presumably all have the intuition that other people have conscious experience. Thus it's not usually explicitly spelled out for parsimony.

  • But what about a "weaker" solipsism of the kind that "SOME people have consciousness" ? How can we assert as fact -rationally- that "(ALL) people are conscious"? It is probably ETHICALLY obvious statement, but is it rationally? May 15 at 17:41
  • I deal with solipsism, not by a strictly rational approach, but an empirical one also. If we define 'consciousness' with an operational definition, then we what we have is not a struggle over a realist's quest to demonstrate that some mystical "mental" essences are met, but rather accept that our position is instrumentalist and that is reasonable to infer that if we impute to ourselves consciousness, then while we have no direct access to others', by virtue of empirical measure, they have it too...
    – J D
    May 15 at 17:55
  • For instance, we can apply various psychometrics in conjunction with a Turing test and NCC's and rule out simulation. If a system can walk into a room, appear to be human, complete an MMPI, have a go at a clever game of word play, and we can measure brain activity with fMRI's consistent with our own, what grounds would we have to suspect they are mental zombies?
    – J D
    May 15 at 17:58
  • @GrigorisL. It seems to me the key is to soften up the categorical distinction between mental and physical by moving from substance dualism to property dualism, so to speak.
    – J D
    May 15 at 17:58

If actual humans are philosophical zombies, then none of them have the concept of qualia (if they have any concepts at all). There would be no point in asking a question about possible qualia-free lookalikes of qualia-ful beings, then.

So, either (A) the ability to ask the question about qualia and zombies is itself disproof that we are zombies (or else we couldn't ask the question), or (B) the question is meaningless. To actively make the opposite "assumption" in the OP case would nullify the pragmatic ground for conducting the thought experiment at all.

So, not so much that the assumption is hidden, but that making the assumption is required to ask the given question in the first place. Dennett wouldn't be factually correct about his own theory in saying, "My theory is that actual people, including myself, are philosophical zombies." If he doesn't believe in qualia (or if his concept of qualia is empty), then he's just not talking about things that other people talk about when they proclaim qualia; he's using the same words but his presuppositions fundamentally redirect those words' meanings.


"Why aren't we zombies?" There's the assumption that we aren't, but it's not acknowledged.

You have to understand, the language-game 'Philosophical Zombies' is above all a thought experiment. Whether we personally are not zombies, or whether zombies are possible, are not subject to assumption or observation - but, definition in this context. The thought experiment begins there, with looking to consequences if the definition is allowed to stand. So really, Dennett conducts a sleight-of-hand, which personally I don't think stands scrutiny, he just says what we call inner experience isn't really that, when clearly definitionally it is - a la cogito.

P-Zombies is the parallel of the Turing Test, where there is the recognition 'all we have' for other humans seems to be that we pass such a test of acting conscious, and so allows us to focus on the gap between our experience of ourselves and how we experience others, and examine our intuitions about ourselves and others.

To me the critical piece for this topic, which I find all too frequently bizarrely and to my mind inexplicably neglected, is The Private Language Argument. Take Wittgenstein's points about pain, a topic you raise:

"What would it be like if human beings showed no outward signs of pain (did not groan, grimace, etc.)? Then it would be impossible to teach a child the use of the word 'tooth ache'." Well, let's assume the child is a genius and itself invents a name for the sensation! But then, of course, he couldn't make himself understood when he used the word. So does he understand the name, without being able to explain its meaning to anyone? But what does it mean to say that he has 'named his pain'? How has he done this naming of pain?! -PI 257

He has a lot more to say on this, and the full Private Language Argument was not strictly developed by Wittgenstein but from his work.

This quote though points us at intersubjectivity. We do generally, if we are not solipsists, begin with the assumption other humans are like ourselves, and, that is functional and useful, in constructing our world and reality - like so: Indra's Net. That is, whether or not we consider other humans to 'really' be like ourselves, if we at least 'act' like they are, then we can engage in this peer-to-peer reality where our experiences are named and organised through engaging in language games, and we greatly extend our experiences and understanding by acting like other people are like ourselves - and, beliefs to the contrary aren't really functional. Through language tools like 'chunking' and assembling 'salience landscapes', and forming 'explanatory layers' that use those, we focus on the bits of the world where we can have influence, enabling our mental model of reality to give us 'cognitive grip' on our experiences. See detailed discussion here: According to the major theories of concepts, where do meanings come from?

The Turing Test in practice is subject to endless iterations and reforming, because despite superficial plausability in practice we just don't feel that engaging in text-based chat does indicate the presence of inner experience, though it can apparently fool some people some of the time (I'd suggest this was actually done in bad faith for attention, which it got, given the substantial editing of the chats involved). But, the idea of the Turing Test points towards the shift from thinking about what subjectivity 'is' to what it does for us. What we really look for in a Turing Test is evidence of subjective experience like our own, manifested by mirroring, empathy, and sponteneous responses to internal experiences like our own. When we think more deeply, these may not be good criteria at all, and while we can point at structural/functional attributes like manifesting a strange-loop, there is a real risk of suffering occuring that we are blind to by only recognising human-like sentience, as discussed under Bostrom's 'mind crime'.

I would explain the deep roots of this gap, between the idea of the Turing Test and the practice, by looking to how we expect a deeper mirroring by other humans: for them to deduce things about our experience by queues like wincing, and that the assumptions involved in that pre-exist our capacities to make sense of our experiences by naming them, involved in language. We just can't begin to sift noise for signal, and begin to form tractable models of the world, without accepting it. Babies isolated from interaction die, babies deprived of verbal language develop their own (babbling, hand gestures, etc), and risk never becoming fully cognitively developed if the don't get human interaction (see children raised by wolves, or severely neglected). Human brains fully developing, and language, arise together. An AGI could potentially arise out of language itself, in the way AlphaZero generated a chess player, this is I think comparable to how some twins sponteneously generate their own language from the evolutionary trigger of babbling (associated with FoxP2 genes, plus honed by mirror neurons).

We can observe degrees of intersubjectivity with animals: How to define intelligence amongst animals

We can I think have experiences without language, new-born babies do, although they quickly learn to cry when hungry, reach when they want to be picked up, focus their eyes and make eye contact to show interest or ask for attention, mimicry, and so on - which in this context are language. With distinct developments in children's quality of intersubjectivity, like the ability to decieve others that usually develops around age three. Our observations themselves, rapidly become theory-laden, through the application of language. And a huge amount of human cognition and communication is about picking up implicit and contextual queues, which is highlighted by trying to communicate with computers, and we can relate evolutionarily to the neocortex (Dunbar Number) and the Default Mode Network. Simply participating in interactions with other agents, can begin to develop language.

I feel that the distinction in science between phenomena and theory, is a useful model for understanding the relation between personal experience (not private, but intersubjectively-informed) and language. Discussed here: Is scientific knowledge personal or general? We use tools like consilience and examining our cognitive biasees, to filter what about our experiences is intersubjective, and would be experienced by others in a similar way if they were in our situation.

We are enculturated into a peer-to-peer reality, but there is the capacity for a 'hard fork' or paradigm shift, if a new framing can take enough people into it's language game. This can help us understand the problems of interspecies communication.

  • 1
    That "mindcrime" link is super interesting. Apr 16, 2023 at 18:29
  • You wrote, "So really, Dennett conducts a sleight-of-hand, which personally I don't think stands scrutiny, he just says what we call inner experience isn't really that, when clearly definitionally it is - a la cogito." I don't understand any of this. Could you clarify what you mean, please? Apr 17, 2023 at 9:54
  • @MatthewChristopherBartsh: Descartes cogito ergo sum is considered to evidence the certainty we have that we are a thing having experiences, even if we doubt the nature of the experiences. That is not deduced or inferred, but considered self-evident, & I would argue - definitional. Our experiencing subjectivity, precurses anything else we can access or come to know about the world, so Dennett claims to 'build a house with such bricks which proves bricks aren't real'.
    – CriglCragl
    Apr 17, 2023 at 14:05
  • But a p-zombie (if the p-zombie idea makes sense) would be just as likely to say "Cogito ergo sum" as a normal person, and be just as likely to say they have qualia, and consciousness. Apr 17, 2023 at 15:29
  • @MatthewChristopherBartsh: Indeed. That is the game though, contrasting that to our personal direct experience of ourselves. If we are to doubt our personal direct experience, then we can surely make no headway with anything, we may be brains in jars, or we may be made of glass, or any other thing, & progress in our inferences would be impossible - yet, we do seem to make useful inferences..
    – CriglCragl
    Apr 17, 2023 at 18:45

The Stanford Encyclopedia of Philosophy article called "Zombies" (...) makes no mention of an assumption (...) that normal human beings (...) have qualia and conciousness.

The two sources that you yourself quote give the appropriate answer:

Unlike the ones in films or witchcraft, they are exactly like us in all physical respects but without conscious experiences -- Stanford Encyclopedia of Philosophy

A philosophical zombie argument is a philosophical thought experiment which conceptualizes a hypothetical being that is physically identical to and indistinguishable from a normal person, but does not have conscious experience -- Wikipedia

Zombies here are said to be like us, or indistinguishable from a normal person, except for their lack of conscious experience. This is enough for the reader to be able to infer that these authors assume that normal humans have conscious experience.

I don't see where is the problem. Philosophy is not formal logic. Readers are assumed to be able to infer what is left implicit when it is implied by what is said.

  • The problem, as I see it, is that the readers mostly do not know that anyone has ever said that it is not true that ordinary humans have qualia and conciousness. The writers on the other hand all know this because they have read Dan Dennett and maybe Keith Frankish. So they would seem to be deliberately keeping the reader in the dark (no pun intended). And rather than stating openly that ordinary humans have qualia and are conscious, they make the claim subtly, subliminally, one might say, by saying "the same as us but not conscious". Apr 16, 2023 at 18:18
  • "Subliminally" is not the best word. Maybe I mean that by not explicitly stating that normal humans are conscious they might be, intentionally or not, conveying the idea that this issue is not "up for debate", as they say, and questioning this assumption will not be regarded as constructive. Do you see what I mean? By not explicitly making it a premise, one implies that it isn't relevant, and isn't a "legitimate target". The reader or interlocutor is thus, perhaps, intimidated slightly and/or manipulated into not asking about this, or even thinking about it. He can expect to be ridiculed. Apr 17, 2023 at 9:50
  • @MatthewChristopherBartsh I still don't see any problem. The articles you incriminate discuss philosophical zombies, not whether we have consciousness. 2. "they might be, intentionally or not" There is no reason to see this as intentional. leaving obvious premises implicit is not only standard practice but in fact what everybody does. We do it in ordinary life because time is of the essence and we don't want to be fussy, and academics do it because they assume the reader can do the maths. These articles are also not for the general population. They are targeted at an informed audience. Apr 20, 2023 at 8:56

Zombies - SEP

The article in question (First published Mon Sep 8, 2003; substantive revision Sat Mar 25, 2023) explicitly states the usual assumption in the last paragraph of Section 1.


The usual assumption is that none of us is actually a zombie, and that zombies cannot exist in our world. The central question, however, is not whether zombies can exist in our world, but whether they, or a whole zombie world (which is sometimes a more appropriate idea to work with), are possible in some broader sense.

What is it like to be a bat? - WP


Thomas Nagel - "An organism has conscious mental states if and only if there is something that it is like to be that organism – something that it is like for the organism."

Philosophical Zombie - WP


Philosophical zombies are associated with David Chalmers, but it was philosopher Robert Kirk who first used the term "zombie" in this context in 1974. Before that, Keith Campbell made a similar argument in his 1970 book Body and Mind, using the term "Imitation Man."

Are There Philosophical Zombies?

Talk by David Chalmers


Phenomenal consciousness: The subjective experience of mind and world.

A being is conscious if there is something it is like to be that being.

A human is conscious. Dogs are probably conscious. Rocks are probably not conscious.

A philosophical zombie is a being that is physically identical to a conscious human being, but that is not conscious.

There is nothing it is like to be a philosophical zombie.

Conscious and Unconscious Human Cognition Is Explicit in the Definition of Philosophical Zombies

I am conscious of my inferences that other living humans are conscious, that living dogs are conscious, and that rocks are not conscious. I am conscious that it appears as if my inferences in this domain arise as the product of an unconscious process as described by Hermann von Helmholtz. I am conscious of my ability to doubt or question these inferences. If philosophical zombies exist, and if I have interacted with them, then they have fooled me into thinking they are human like me, and by definition I would not be able to detect the difference between a human and a philosophical zombie! The actions and behaviors of a philosophical zombie would be driven totally by some sort of unconscious cognition but by definition every human would infer that the zombie is conscious!


The short answer is yes. The assumption, the default position, is that humans have consciousness. Even as a thought experiment, I find the definition of a p-zombie unsatisfactory. Suppose someone slaps you and the p-zombie in the face for no reason apparently. You and the p-zombie cry out in pain and shout and swear at your assailant. The p-zombie feels pain just like you, but is not conscious of the insult implied in the slap. So why does it shout and curse just like you? The definition is inconsistent. To suggest that the only thing that I can be absolutely sure of, my consciousness, is an illusion is sophistry. Consider that the difference between consciousness and the illusion of consciousness is indiscernible. Then, employing Leibniz's principle of indiscernibles, they are logically identical.


You are right in supposing that there is something significant missing from almost all presentations of Chalmers' zombie argument, but it is not the issue you suppose; it is the question of whether conceivability does entail possibility.

I do not think one has to be a committed materialist to find something to be deeply skeptical of in the form of this argument. After all, conceiving of something seems to be merely the first step in finding out whether it is possible, and we are all well aware of conceptions that, while widely held to be true at one time, turned out to be impossible or incoherent. There is also the matter of the many unsolved conjectures in mathematics, such as the Collatz conjecture, where both their truth and falsity seem conceivable, yet these alternatives cannot both be true. Then there is the sense in which the premises that one rejects have to be conceived of in order to reject them. Furthermore, if there is any objectivity to the zombie question, then it would seem that we must accept their possibility merely on the basis of David Chalmers finding them conceivable, never mind what we think!

This concern cannot be dismissed by noting that, in ordinary usage, 'conceivable' and 'possible' have considerable semantic overlap, such that there are many cases where they can, in practice, be used interchangeably. While I suspect that this plays a big part in the easy acceptance of Chalmers' entailment premise, it amounts to question-begging via equivocation leading to a de-facto (if unacknowledged) conflation of 'conceivable' and 'possible'.

Chalmers is, of course, well aware of these issues, and has attempted to address them at length, such as in a 2002 paper appropriately entitled 'Does Conceivability Entail Possibility?' Here, he sets forth three different notions of conceivability, and combines them to produce eight different sorts. In the appendix, he reveals what sort works for the zombie argument: it is the premise that zombies are, in his terms, ideally primarily positively conceivable.

That 'ideally' is, just by itself, a highly significant qualification. Unlike his prima facie conceivability, where the premise in question is not immediately and obviously false, a claim of ideal conceivability is a claim that the premise remains conceivable after "ideal rational reflection".

Rather tellingly, Chalmers then considers several ways of defining what "ideal rational reflection" means, and finds difficulty with all of them. He writes "I will not try to give a substantive characterization of what good reasoning consists in, or of what counts as a cognitive limitation to be idealized away from. I suspect that any such attempt would end up being open-ended and incomplete." Well, yes, and this, of course, would carry over to the zombie argument.

Chalmers has developed this line of thought via two-dimensional semantics (see 'The Two-Dimensional Argument Against Materialism', 2009.) The argument has become even more complex but has not been able to either shed the need for the conceivability of zombies to be ideal or provide an uncontentious argument for it being so, and he resorts to offering arguments for its plausibility by invoking other, equally contentious, anti-materialist arguments.

For the purpose of answering your question, I think all this makes it clear that the zombie argument is very far from being the simple and straightforward knockout blow to physicalism that it might appear to be when presented in its two-premises-to-a-conclusion form.

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