Philosophy of mind event at
De La Salle University, Manila, 27 March 2012 Chalmers is best known for formulating what he calls the "
hard problem of consciousness," in both his 1995 paper "Facing Up to the Problem of Consciousness" and his 1996 book
The Conscious Mind. He makes a distinction between "easy" problems of consciousness, such as explaining object discrimination or verbal reports, and the single hard problem, which could be stated "why does the
feeling which accompanies awareness of sensory information exist at all?" The essential difference between the (
cognitive) easy problems and the (
phenomenal) hard problem is that the former are at least theoretically answerable via the dominant strategy in the philosophy of mind:
physicalism. Chalmers argues for an "
explanatory gap" from the objective to the subjective, and criticizes physicalist explanations of mental experience, making him a
dualist. Chalmers characterizes his view as "
naturalistic dualism": naturalistic because he believes mental states
supervene "naturally" on physical systems (such as brains); dualist because he believes mental states are
ontologically distinct from and not reducible to physical systems. He has also characterized his view by more traditional formulations such as
property dualism. In support of this, Chalmers is famous for his commitment to the logical (though, not natural) possibility of
philosophical zombies. These zombies are complete physical duplicates of human beings, lacking only qualitative experience. Chalmers argues that since such zombies are conceivable to us, they must therefore be logically possible. Since they are logically possible, then
qualia and
sentience are not fully explained by physical properties alone; the facts about them are
further facts. Instead, Chalmers argues that consciousness is a fundamental property ontologically autonomous of any known (or even possible) physical properties, and that there may be lawlike rules which he terms "psychophysical laws" that determine which physical systems are associated with which types of qualia. He further speculates that all
information-bearing systems may be conscious, leading him to entertain the possibility of conscious thermostats and a qualified
panpsychism he calls
panprotopsychism. Chalmers maintains a formal agnosticism on the issue, even conceding that the viability of panpsychism places him at odds with the majority of his contemporaries. According to Chalmers, his arguments are similar to a line of thought that goes back to
Leibniz's 1714
"mill" argument; the first substantial use of philosophical "zombie" terminology may be
Robert Kirk's 1974 "Zombies vs. Materialists". After the publication of Chalmers's landmark paper, more than twenty papers in response were published in the
Journal of Consciousness Studies. These papers (by
Daniel Dennett,
Colin McGinn,
Francisco Varela,
Francis Crick, and
Roger Penrose, among others) were collected and published in the book
Explaining Consciousness: The Hard Problem.
John Searle critiqued Chalmers's views in
The New York Review of Books. With
Andy Clark, Chalmers has written "
The Extended Mind", an article about the borders of the mind. s could be conscious, and suggested that they were probably not conscious, but could become serious candidates for consciousness within a decade.
Philosophy of language Chalmers has published works on the "theory of reference" concerning how words secure their referents. He, together with others such as
Frank Jackson, played a major role in developing
two-dimensional semantics.
Background Before
Saul Kripke delivered his famous lecture series
Naming and Necessity in 1970, the
descriptivism advocated by
Gottlob Frege and
Bertrand Russell was the orthodoxy. Descriptivism suggests that a name is an abbreviation of a description, which is a set of properties. This name secures its reference by a process of properties fitting: whichever object fits the description most, is the referent of the name. Therefore, the description provides the sense of the name, and it is through this sense that the reference of the name is determined. However, as
Kripke argued in
Naming and Necessity, a name does not secure its reference via any process of description fitting. Rather, a name determines its reference via a historical-causal link tracing back to the process of naming. And thus, Kripke thinks that a name does not have a sense, or, at least, does not have a sense which is rich enough to play the reference-determining role. Moreover, a name, in Kripke's view, is a
rigid designator, which refers to the same object in all
possible worlds. Following this line of thought, Kripke suggests that any scientific identity statement such as "Water is H2O" is also a necessary statement, i.e. true in all possible worlds. Kripke thinks that this is a phenomenon that descriptivism cannot explain. And, as also proposed by
Hilary Putnam and Kripke himself, Kripke's view on names can also be applied to the reference of
natural kind terms. The kind of theory of reference that is advocated by Kripke and Putnam is called the
direct reference theory.
Two-dimensional semantics Chalmers disagrees with Kripke, and direct reference theorists in general. He thinks that there are two kinds of intension of a natural kind term, a stance called
two-dimensionalism. For example, the statement "Water is H2O" expresses two distinct propositions, often referred to as a
primary intension and a
secondary intension, which together form its meaning. The
primary intension of a word or sentence is its
sense, i.e., is the idea or method by which we find its referent. The primary intension of "water" might be a description, such as "the substance with water-like properties". The entity identified by this intension could vary in different hypothetical worlds. In the
twin Earth thought experiment, for example, inhabitants might use "water" to mean their equivalent of water, even if its chemical composition is not H2O. Thus, for that world, "water" does not refer to H2O. He argues that a dispute is best characterized as "verbal" when it concerns some sentence S which contains a term T such that (i) the parties to the dispute disagree over the meaning of T, and (ii) the dispute arises solely because of this disagreement. In the same work, Chalmers proposes certain procedures for the resolution of verbal disputes. One of these he calls the "elimination method", which involves eliminating the contentious term and observing whether any dispute remains.
Technology and virtual reality Chalmers addressed the issue of
virtual and non-virtual worlds in his 2022 book
Reality+. While Chalmers recognises that virtual reality is not the same as non-virtual reality, he does not consider virtual reality to be an illusion, but rather a "genuine reality" in its own right. Chalmers sees virtual reality as potentially offering as meaningful a life as non-virtual reality, and argues that we could already be inhabitants of a
simulation without knowing it. Chalmers proposes that computers are forming a form of "exo-cortex", where a part of human cognition is 'outsourced' to corporations such as
Apple and
Google. He was a featured philosopher in the 2020
Daily Nous series on
GPT-3, which he described as "one of the most interesting and important AI systems ever produced." == Personal life ==