The philosophical zombie or p-zombie argument is a thought experiment in philosophy of mind and philosophy of perception that imagines a being that, if it existed, logically disproves the idea that physical stuff is all that is required to explain consciousness. Such a zombie would be indistinguishable from a normal human being but lack conscious experience, qualia, or sentience.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. The argument sometimes takes the form of hypothesizing a zombie world, indistinguishable from our world, but lacking first person experiences in any of the beings of that world.
A thought experiment considers a hypothesis, theory, or principle for the purpose of thinking through its consequences.
Philosophy of mind is a branch of philosophy that studies the ontology, nature, and relationship of the mind to the body. The mind–body problem is a paradigm issue in philosophy of mind, although other issues are addressed, such as the hard problem of consciousness, and the nature of particular mental states. Aspects of the mind that are studied include mental events, mental functions, mental properties, consciousness, the ontology of the mind, the nature of thought, and the relationship of the mind to the body.
The philosophy of perception is concerned with the nature of perceptual experience and the status of perceptual data, in particular how they relate to beliefs about, or knowledge of, the world. Any explicit account of perception requires a commitment to one of a variety of ontological or metaphysical views. Philosophers distinguish internalist accounts, which assume that perceptions of objects, and knowledge or beliefs about them, are aspects of an individual's mind, and externalist accounts, which state that they constitute real aspects of the world external to the individual. The position of naïve realism—the 'everyday' impression of physical objects constituting what is perceived—is to some extent contradicted by the occurrence of perceptual illusions and hallucinations and the relativity of perceptual experience as well as certain insights in science. Realist conceptions include phenomenalism and direct and indirect realism. Anti-realist conceptions include idealism and skepticism.
Philosophical zombie arguments are used in support of mind-body dualism against forms of physicalism such as materialism, behaviorism and functionalism. It is an argument against the idea that the "hard problem of consciousness" (accounting for subjective, intrinsic, first person, what-it's-like-ness) could be answered by purely physical means. Proponents of the argument, such as philosopher David Chalmers, argue that since a zombie is defined as physiologically indistinguishable from human beings, even its logical possibility would be a sound refutation of physicalism, because it would establish the existence of conscious experience as a further fact.However, physicalists like Daniel Dennett counter that philosophical zombies are logically incoherent and thus impossible.
In logic and philosophy, an argument is a series of statements, called the premises or premisses, intended to determine the degree of truth of another statement, the conclusion. The logical form of an argument in a natural language can be represented in a symbolic formal language, and independently of natural language formally defined "arguments" can be made in math and computer science.
In philosophy, physicalism is the metaphysical thesis that "everything is physical", that there is "nothing over and above" the physical, or that everything supervenes on the physical. Physicalism is a form of ontological monism—a "one substance" view of the nature of reality as opposed to a "two-substance" (dualism) or "many-substance" (pluralism) view. Both the definition of "physical" and the meaning of physicalism have been debated.
Materialism is a form of philosophical monism which holds that matter is the fundamental substance in nature, and that all things, including mental states and consciousness, are results of material interactions. According to philosophical materialism, mind and consciousness are by-products or epiphenomena of material processes without which they cannot exist. This concept directly contrasts with idealism, where mind and consciousness are first-order realities to which matter is subject and material interactions are secondary.
Philosophical zombies are associated with David Chalmers, but it was philosopher Robert Kirk who first used the term "zombie" in this context in 1974. Prior to that, Karlyn Campbell made a similar argument in his 1970s book "Body and Mind," using the term "Imitation Man."Chalmers further developed and popularized the idea in his work.
There has been a lively debate about what the zombie argument shows. Critics who primarily argue that zombies are not conceivable include Daniel Dennett, Nigil J. T. Thomas , David Braddon-Mitchell , and Robert Kirk . Critics who assert mostly that conceivability does not entail possibility include Katalin Balog , Keith Frankish , Christopher Hill , and Stephen Yablo , and critics who prominently question the logical validity of the argument include George Bealer.
Daniel Clement Dennett III is an American philosopher, writer, and cognitive scientist whose research centers on the philosophy of mind, philosophy of science, and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science.
Robert Kirk is an emeritus professor in the Department of Philosophy at the University of Nottingham. He is known for his work on philosophical zombies—putatively unconscious beings physically and behaviourally identical to human beings. Although Kirk did not invent this idea, he introduced the term zombie in his 1974 papers "Sentience and Behaviour" and "Zombies v. Materialists". In the latter he offered a formulation of physicalism that aimed to make clear that if zombies are possible, physicalism is false: an argument that was not much noticed until David Chalmers's development of it in The Conscious Mind. Kirk himself had reversed his position earlier, and has argued against the zombie idea in a number of books and articles on physicalism and consciousness.
Christopher S. Hill is an American philosopher and William Herbert Perry Faunce Professor of Philosophy at Brown University. He is known for his expertise on consciousness and philosophy of mind.
Kirk, in 2003, summed up the current state of the debate:
In spite of the fact that the arguments on both sides have become increasingly sophisticated — or perhaps because of it — they have not become more persuasive. The pull in each direction remains strong.
However, two years later in 2005, Kirk would argue that zombies are inconceivable.
In a 2013 survey of philosophers conducted by Bourget and Chalmers, 23.3% of the respondents felt P Zombies were metaphysically possible. The other responses broke down this way:
35.6% said P Zombies were conceivable but not metaphysically possible; 23.3% said they were metaphysically possible; 16.0% said they were inconceivable; and 25.1% responded "other."
Though philosophical zombies are widely used in thought experiments, the detailed articulation of the concept is not always the same. P-zombies were introduced primarily to argue against specific types of physicalism such as behaviorism, according to which mental states exist solely as behavior. Belief, desire, thought, consciousness, and so on, are only behavior (whether external behavior or internal behavior) or tendencies towards behaviors. A p-zombie that is behaviorally indistinguishable from a normal human being but lacks conscious experiences is therefore not logically possible according to the behaviorist [ citation needed ], so an appeal to the logical possibility of a p-zombie furnishes an argument that behaviorism is false. Proponents of zombie arguments generally accept that p-zombies are not physically possible, while opponents necessarily deny that they are metaphysically or even logically possible.
The unifying idea of the zombie is of a human that has no conscious experience, but one might distinguish various types of zombie used in different thought experiments as follows:
Zombie arguments often support lines of reasoning that aim to show that zombies are metaphysically possible in order to support some form of dualism – in this case the view that the world includes two kinds of substance (or perhaps two kinds of property); the mental and the physical.According to physicalism, physical facts determine all other facts. Since any fact other than that of consciousness may be held to be the same for a p-zombie and a normal conscious human, it follows that physicalism must hold that p-zombies are either not possible or are the same as normal humans.
The zombie argument is a version of general modal arguments against physicalism such as that of Saul Kripkeand the kind of physicalism known as type-identity theory. Further such arguments were notably advanced in the 1970s by Thomas Nagel (1970; 1974) and Robert Kirk (1974) but the general argument was most famously developed in detail by David Chalmers in The Conscious Mind (1996). According to Chalmers one can coherently conceive of an entire zombie world, a world physically indistinguishable from this world but entirely lacking conscious experience. The counterpart of every conscious being in our world would be a p-zombie. Since such a world is conceivable, Chalmers claims, it is metaphysically possible, which is all the argument requires. Chalmers states: "Zombies are probably not naturally possible: they probably cannot exist in our world, with its laws of nature." The outline structure of Chalmers' version of the zombie argument is as follows:
The above is a strong formulation of the zombie argument. There are other formulations of the zombies-type argument which follow the same general form. The premises of the general zombies argument are implied by the premises of all the specific zombie arguments. A general zombies argument is in part motivated by potential disagreements between various anti-physicalist views. For example, an anti-physicalist view can consistently assert that p-zombies are metaphysically impossible but that inverted qualia (such as inverted spectra) or absent qualia (partial zombiehood) are metaphysically possible. Premises regarding inverted qualia or partial zombiehood can substitute premises regarding p-zombies to produce variations of the zombie argument. The metaphysical possibility of a physically indistinguishable world with either inverted qualia or partial zombiehood would imply that physical truths don't metaphysically necessitate phenomenal truths. To formulate the general form of the zombies argument, take the sentence 'P' to be true if and only if the conjunct of all microphysical truths of our world obtain, take the sentence 'Q' to be true if some phenomenal truth, that obtains in the actual world, obtains. The general argument goes as follows.
Q can be false in a possible world if any of the following obtains: (1) there exists at least one invert relative to the actual world (2) there is at least one absent quale relative to the actual world (3) all actually conscious beings are p-zombies (all actual qualia are absent qualia).
If one accepts two-dimensional semantics, Chalmers' argument is logically valid. Some philosophers accept its validity but dispute its soundness, arguing that its premises are false. Zombies might not actually be conceivable or, if they are, just because they are conceivable, that might not mean that they are possible. Chalmers has argued that zombies are conceivable, saying "it certainly seems that a coherent situation is described; I can discern no contradiction in the description."This leads to the questions of the relevant notion of "possibility": if something is conceivable, does that mean it is possible? Most physicalist responses deny that the premise of a zombie scenario is possible.
Many physicalist philosophers have argued that this scenario eliminates itself by its description; the basis of a physicalist argument is that the world is defined entirely by physicality; thus, a world that was physically identical would necessarily contain consciousness, as consciousness would necessarily be generated from any set of physical circumstances identical to our own.
One can hold that zombies are a logical possibility but not a metaphysical possibility. If logical possibility does not entail metaphysical possibility across the domain of relevant truths, then the mere logical possibility of zombies is not sufficient to establish their metaphysical possibility. The zombie argument claims that one can tell by the power of reason that such a "zombie scenario" is metaphysically possible. Chalmers states; "From the conceivability of zombies, proponents of the argument infer their metaphysical possibility"and argues that this inference, while not generally legitimate, is legitimate for phenomenal concepts such as consciousness since we must adhere to "Kripke's insight that for phenomenal concepts, there is no gap between reference-fixers and reference (or between primary and secondary intentions)." That is, for phenomenal concepts, conceivability implies possibility. According to Chalmers, whatever is logically possible is also, in the sense relevant here, metaphysically possible.
Another response is the denial of the idea that qualia and related phenomenal notions of the mind are in the first place coherent concepts. Daniel Dennett and others argue that while consciousness and subjective experience exist in some sense, they are not as the zombie argument proponent claims. The experience of pain, for example, is not something that can be stripped off a person's mental life without bringing about any behavioral or physiological differences. Dennett believes that consciousness is a complex series of functions and ideas. If we all can have these experiences the idea of the p-zombie is meaningless.
Dennett argues that "when philosophers claim that zombies are conceivable, they invariably underestimate the task of conception (or imagination), and end up imagining something that violates their own definition".He coined the term "zimboes" – p-zombies that have second-order beliefs – to argue that the idea of a p-zombie is incoherent; "Zimboes thinkZ they are conscious, thinkZ they have qualia, thinkZ they suffer pains – they are just 'wrong' (according to this lamentable tradition), in ways that neither they nor we could ever discover!". Under (reductive) physicalism, one is inclined to believe either that anyone including oneself might be a zombie, or that no one can be a zombie – following from the assertion that one's own conviction about being, or not being a zombie is (just) a product of the physical world and is therefore no different from anyone else's. P-zombies in an observed world would be indistinguishable from the observer, even hypothetically (when the observer makes no assumptions regarding the validity of their convictions). Furthermore, when concept of self is deemed to correspond to physical reality alone (reductive physicalism), philosophical zombies are denied by definition. 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" contradicting the original definition of a zombie.
Verificationismstates that, for words to have meaning, their use must be open to public verification. Since it is assumed that we can talk about our qualia, the existence of zombies is impossible. A related argument is that of "zombie-utterance". If someone were to say they love the smell of some food, a zombie producing the same reaction would be perceived as a person having complex thoughts and ideas in their head indicated by the ability to vocalize it. If zombies were without awareness of their perceptions the idea of uttering words could not occur to them. Therefore, if a zombie has the ability to speak, it is not a zombie.
Artificial intelligence researcher Marvin Minsky saw the argument as circular. The proposition of the possibility of something physically identical to a human but without subjective experience assumes that the physical characteristics of humans are not what produces those experiences, which is exactly what the argument was claiming to prove. zoombies existed, they would refute dualism because they would show that consciousness is not nonphysical, i.e., is physical. Paralleling the argument from Chalmers: It's conceivable that zoombies exist, so it's possible they exist, so dualism is false. Given the symmetry between the zombie and zoombie arguments, we can't arbitrate the physicalism/dualism question a priori.Richard Brown agrees that the zombie argument is circular. To show this, he proposes "zoombies", which are creatures nonphysically identical to people in every way and lack phenomenal consciousness. If
Stephen Yablo's (1998) response is to provide an error theory to account for the intuition that zombies are possible. Notions of what counts as physical and as physically possible change over time so conceptual analysis is not reliable here. Yablo says he is "braced for the information that is going to make zombies inconceivable, even though I have no real idea what form the information is going to take."
The zombie argument is difficult to assess because it brings to light fundamental disagreements about the method and scope of philosophy itself and the nature and abilities of conceptual analysis. Proponents of the zombie argument may think that conceptual analysis is a central part of (if not the only part of) philosophy and that it certainly can do a great deal of philosophical work. However others, such as Dennett, Paul Churchland and W.V.O. Quine, have fundamentally different views. For this reason, discussion of the zombie argument remains vigorous in philosophy.
Some accept modal reasoning in general but deny it in the zombie case. Christopher S. Hill and Brian P. Mclaughlin suggest that the zombie thought experiment combines imagination of a "sympathetic" nature (putting oneself in a phenomenal state) and a "perceptual" nature (imagining becoming aware of something in the outside world). Each type of imagination may work on its own, but they're not guaranteed to work when both used at the same time. Hence Chalmers's argument needn't go through. 448 Moreover, while Chalmers defuses criticisms of the view that conceivability can tell us about possibility, he provides no positive defense of the principle. As an analogy, the generalized continuum hypothesis has no known counterexamples, but this doesn't mean we must accept it. And indeed, the fact that Chalmers concludes we have epiphenomenal mental states that don't cause our physical behavior seems one reason to reject his principle. :449–51:
Another way to construe the zombie hypothesis is epistemically – as a problem of causal explanation, rather than as a problem of logical or metaphysical possibility. The "explanatory gap" – also called the "hard problem of consciousness" – is the claim that (to date) no one has provided a convincing causal explanation of how and why we are conscious. It is a manifestation of the very same gap that (to date) no one has provided a convincing causal explanation of how and why we are not zombies.
Frank Jackson's Mary's room argument is based around a hypothetical scientist, Mary, who is forced to view the world through a black-and-white television screen in a black and white room. Mary is a brilliant scientist who knows everything about the neurobiology of vision. Even though Mary knows everything about color and its perception (e.g. what combination of wavelengths makes the sky seem blue), she has never seen color. If Mary were released from this room and were to experience color for the first time, would she learn anything new? Jackson initially believed this supported epiphenomenalism (mental phenomena are the effects, but not the causes, of physical phenomena) but later changed his views to physicalism, suggesting that Mary is simply discovering a new way for her brain to represent qualities that exist in the world.
Swampman is an imaginary character introduced by Donald Davidson. If Davidson goes hiking in a swamp and is struck and killed by a lightning bolt while nearby another lightning bolt spontaneously rearranges a bunch of molecules so that, entirely by coincidence, they take on exactly the same form that Davidson's body had at the moment of his untimely death then this being, 'Swampman', has a brain structurally identical to that which Davidson had and will thus presumably behave exactly like Davidson. He will return to Davidson's office and write the same essays he would have written, recognize all of his friends and family and so forth.
John Searle's Chinese room argument deals with the nature of artificial intelligence: it imagines a room in which a conversation is held by means of written Chinese characters that the subject cannot actually read, but is able to manipulate meaningfully using a set of algorithms. Searle holds that a program cannot give a computer a "mind" or "understanding", regardless of how intelligently it may make it behave. Stevan Harnad argues that Searle's critique is really meant to target functionalism and computationalism, and to establish neuroscience as the only correct way to understand the mind.
Consciousness Explained is a 1991 book by the American philosopher Daniel Dennett, in which the author offers an account of how consciousness arises from interaction of physical and cognitive processes in the brain.
Simulated reality is the hypothesis that reality could be simulated—for example by quantum computer simulation—to a degree indistinguishable from "true" reality. It could contain conscious minds which may or may not be fully aware that they are living inside a simulation. This is quite different from the current, technologically achievable concept of virtual reality. Virtual reality is easily distinguished from the experience of actuality; participants are never in doubt about the nature of what they experience. Simulated reality, by contrast, would be hard or impossible to separate from "true" reality. There has been much debate over this topic, ranging from philosophical discourse to practical applications in computing.
David John Chalmers is an Australian philosopher and cognitive scientist specializing in the areas of philosophy of mind and philosophy of language. He is Professor of Philosophy and Director of the Centre for Consciousness at the Australian National University. He is also a University Professor, Professor of Philosophy and Neural Science, and a Director of the Center for Mind, Brain and Consciousness at New York University. In 2013, he was elected a Fellow of the American Academy of Arts & Sciences.
In philosophy of mind and consciousness, the explanatory gap is the difficulty that physicalist theories have in explaining how physical properties give rise to the way things feel when they are experienced. It is a term introduced by philosopher Joseph Levine. In the 1983 paper in which he first used the term, he used as an example the sentence, "Pain is the firing of C fibers", pointing out that while it might be valid in a physiological sense, it does not help us to understand how pain feels.
Eliminative materialism is the claim that people's common-sense understanding of the mind is false and that certain classes of mental states that most people believe in do not exist. It is a materialist position in the philosophy of mind. Some supporters of eliminativism argue that no coherent neural basis will be found for many everyday psychological concepts such as belief or desire, since they are poorly defined. Rather, they argue that psychological concepts of behaviour and experience should be judged by how well they reduce to the biological level. Other versions entail the non-existence of conscious mental states such as pain and visual perceptions.
The knowledge argument is a philosophical thought experiment proposed by Frank Jackson in his article "Epiphenomenal Qualia" (1982) and extended in "What Mary Didn't Know" (1986). The experiment is intended to argue against physicalism—the view that the universe, including all that is mental, is entirely physical. The debate that emerged following its publication became the subject of an edited volume—There's Something About Mary (2004)—which includes replies from such philosophers as Daniel Dennett, David Lewis, and Paul Churchland.
The hard problem of consciousness is the problem of explaining how and why sentient organisms have qualia or phenomenal experiences—how and why it is that some internal states are felt states, such as heat or pain, rather than unfelt states, as in a thermostat or a toaster. The philosopher David Chalmers, who introduced the term "hard problem" of consciousness, contrasts this with the "easy problems" of explaining the ability to discriminate, integrate information, report mental states, focus attention, etc. Easy problems are easy because all that is required for their solution is to specify a mechanism that can perform the function. That is, their proposed solutions, regardless of how complex or poorly understood they may be, can be entirely consistent with the modern materialistic conception of natural phenomena. Chalmers claims that the problem of experience is distinct from this set and that the problem of experience will "persist even when the performance of all the relevant functions is explained".
Daniel Dennett's multiple drafts model of consciousness is a physicalist theory of consciousness based upon cognitivism, which views the mind in terms of information processing. The theory is described in depth in his book, Consciousness Explained, published in 1991. As the title states, the book proposes a high-level explanation of consciousness which is consistent with support for the possibility of strong AI.
The inverted spectrum is the hypothetical concept of two people sharing their color vocabulary and discriminations, although the colors one sees—one's qualia—are systematically different from the colors the other person sees.
In the philosophy of mind, the China brain thought experiment considers what would happen if each member of the Chinese nation were asked to simulate the action of one neuron in the brain, using telephones or walkie-talkies to simulate the axons and dendrites that connect neurons. Would this arrangement have a mind or consciousness in the same way that brains do?
Type physicalism is a physicalist theory, in the philosophy of mind. It asserts that mental events can be grouped into types, and can then be correlated with types of physical events in the brain. For example, one type of mental event, such as "mental pains" will, presumably, turn out to be describing one type of physical event.
"What is it like to be a bat?" is a paper by American philosopher Thomas Nagel, first published in The Philosophical Review in October 1974, and later in Nagel's Mortal Questions (1979). In it, Nagel argues that materialist theories of mind omit the essential component of consciousness, namely that there is something that it is like to be a particular, conscious thing. He argues that an organism has conscious mental states, "if and only if there is something that it is like to be that organism—something it is like for the organism to be itself." Daniel Dennett, a critic of Nagel's argument, nevertheless called this paper "the most widely cited and influential thought experiment about consciousness."
Two-dimensionalism is an approach to semantics in analytic philosophy. It is a theory of how to determine the sense and reference of a word and the truth-value of a sentence. It is intended to resolve the puzzle: How is it possible to discover empirically that a necessary truth is true? Two-dimensionalism provides an analysis of the semantics of words and sentences that makes sense of this possibility. The theory was first developed by Robert Stalnaker, but it has been advocated by numerous philosophers since, including David Chalmers.
In philosophy and certain models of psychology, qualia are defined as individual instances of subjective, conscious experience. The term qualia derives from the Latin neuter plural form (qualia) of the Latin adjective quālis meaning "of what sort" or "of what kind" in a specific instance, like "what it is like to taste a specific apple, this particular apple now".
Interactionism or interactionist dualism is the theory in the philosophy of mind which holds that matter and mind are two distinct and independent substances that exert causal effects on one another. It is one type of dualism, traditionally a type of substance dualism though more recently also sometimes a form of property dualism.
The concept of absent qualia is one of two major Functionalist objections to the existence of qualia, the other being the inverted spectrum hypothesis. Qualia is a philosophical term used to refer to an individual's subjective experience, that is to say, the way something feels to that individual at that particular moment.
Joseph Levine is an American philosopher at the University of Massachusetts Amherst who received his PhD from Harvard University in 1981.
The phenomenal concept strategy (PCS) is an approach within philosophy of mind to provide a physicalist response to anti-physicalist arguments like the explanatory gap and philosophical zombies. The name was coined by Daniel Stoljar. As David Chalmers put it, PCS "locates the gap in the relationship between our concepts of physical processes and our concepts of consciousness, rather than in the relationship between physical processes and consciousness themselves." The idea is that if we can explain why we think there's an explanatory gap, this will defuse the motivation to question physicalism.