Western Philosophical Perspectives on Consciousness

Introduction and Index

Lecture 4 – Western Philosophical Perspectives on Consciousness (Ancient to Contemporary Analytic)

The question of consciousness is the single thread that runs unbroken from the very earliest fragments of Western philosophy to the most technical papers in twenty-first-century analytic philosophy of mind. No other topic has provoked so many radical transformations of method, vocabulary, and metaphysical commitment while remaining, in its core formulation, recognisably the same: what is it for a physical system to have an interior, to be the subject of experience rather than a mere automaton, and how—if at all—can this interior be reconciled with the world as described by physics? This lecture traces that thread from its pre-Socratic glimmer to the present day, lingering on the moments when the problem was sharpened, reconfigured, or apparently solved, only to re-emerge in a new and more intractable form.

The first explicit appearance of something like a concept of consciousness occurs in the Homeric poems, but only negatively: the ψυχή is a shade, a breath, a non-experiential life-principle that departs at death. Real interiority belongs to θυμός and νοῦς, the seat of emotion, planning, and perception while alive. By the time of the pre-Socratics, Alcmaeon of Croton already declares that “the brain provides us the senses of hearing, sight, and smell; from these arise memory and opinion, and from memory and opinion, when they have become stable, knowledge is produced.” Here, in embryo, is the idea that consciousness is the brain’s doing, and that it has degrees.

Plato gives the first systematic analysis. In the Phaedo, the soul is immortal and immaterial; in the Republic it is tripartite—λογιστικόν (rational), θυμοειδές (spirited), and ἐπιθυμητικόν (appetitive). Only the rational part is capable of genuine knowledge and self-awareness; the lower parts operate through images and illusions. The famous allegory of the cave is, among other things, a phenomenology of consciousness-raising: the prisoner’s ascent is a painful expansion of awareness from shadows to forms to the sun itself. Yet Plato never quite explains how an immaterial knower can be affected by material particulars without compromising its simplicity.

Aristotle rejects Plato’s separable soul but retains the intuition that perception and thought require something that can receive form without matter. In De Anima III.5 he distinguishes the passive intellect (which becomes all things) from the active intellect (which makes all things). The active intellect “is separate, unaffected, and unmixed,” and some medieval interpreters (notably Averroes) took it to be a single, shared consciousness for all humanity. Aristotle himself is more cautious, but the passage inaugurates a 2,000-year debate about whether pure awareness is individual or trans-individual, immanent or transcendent.

The Hellenistic schools shift the focus. The Epicureans reduce consciousness to atomic motions in the soul; the Stoics make it the activity of πνεῦμα, a fiery breath that permeates the body and organises perception into a unified field. Both schools treat consciousness naturalistically, but both also struggle to explain its apparent privacy and infallibility. Augustine internalises the Stoic logos: in the Confessions, he discovers the immensity of memory and the immediacy of self-presence (“I am certain that I am”), founding the Western tradition of first-person authority. For Augustine, consciousness is the image of the Trinity in the human mind: memoria, intellectus, voluntas.

Medieval philosophy inherits Aristotle through Arabic and Latin translations and immediately confronts the problem of intentionality. Avicenna’s “flying man” thought experiment argues that a person created in mid-air, deprived of all sensation, would still affirm his own existence, proving the soul’s immediate self-awareness. Aquinas synthesises: the human soul is the substantial form of the body, hence naturally united to it, yet capable of immaterial operations (understanding universals). The agent intellect abstracts intelligible species from phantasms; consciousness arises when the possible intellect is actualised by these species. Aquinas insists that we do not directly perceive our own act of understanding—only indirectly, through its objects. This opens the door to sceptical worries that will not be fully exploited until Descartes.

Descartes is the great rupture. In the Second Meditation he performs the most radical phenomenological reduction before Husserl: everything external, even the body, can be doubted, but the act of doubting cannot be doubted, and in that act the self is revealed as a thinking thing—res cogitans. Consciousness becomes the essence of the mind; extension the essence of body. The problem of interaction is immediate and devastating: how can an unextended thinking substance move extended matter? Malebranche’s occasionalism, Leibniz’s pre-established harmony, and Spinoza’s double-aspect theory are the three great seventeenth-century attempts to save Descartes from himself. Spinoza’s solution is the most elegant: mind and body are the very same thing expressed under different attributes; consciousness is the idea of the body insofar as the body is an actual mode of God/Nature. The hard problem is dissolved by identity, but at the price of pantheism.

British empiricism begins with Locke’s suggestion that consciousness might be separable from any particular substance: “whether the consciousness of past actions be annexed to one individual substance or another is a matter of no consequence.” This opens the possibility of consciousness transfer, inverted spectra, and eventually Chalmers’ fading qualia argument. Berkeley collapses the external world into collections of ideas in perceiving minds; Hume dissolves the mind itself into a bundle of perceptions. Hume’s failure to find an impression of the self is the mirror image of Descartes’ success: where Descartes found indubitable presence, Hume finds absence. Yet Hume cannot explain the apparent unity and continuity of consciousness; he simply declares it a fiction.

Kant’s transcendental turn is the most profound reorientation since Plato. Consciousness is not a thing but the formal unity of experience. The transcendental unity of apperception—“the I think must be able to accompany all my representations”—is the condition of possibility for any coherent experience of objects. Space, time, and the categories are forms imposed by consciousness on the raw manifold of sensibility. The noumenal self is unknowable; we encounter ourselves only as appearance. German idealism radicalises this: for Fichte the ego posits the non-ego; for Schelling nature and spirit are two sides of the absolute; for Hegel consciousness is Geist coming to know itself through history. Schopenhauer breaks ranks by identifying the thing-in-itself as will—a blind, striving force manifested inwardly as consciousness and outwardly as representation.

Phenomenology proper begins with Brentano’s 1874 Psychology from an Empirical Standpoint. Intentionality—the directedness of mental acts upon objects—is the mark of the mental. Husserl takes this up and develops the epoché: the suspension of the natural attitude to describe pure phenomena as they appear. The noema (the objective correlate) and noesis (the act) are inseparable; consciousness is always consciousness-of. Heidegger shifts the focus from pure consciousness to Dasein’s being-in-the-world; Sartre radicalises freedom and denies any substantial ego behind the flux of consciousness.

Twentieth-century analytic philosophy begins with a rejection of both idealism and introspective psychology. Russell’s 1918–1919 lectures on logical atomism and the early Wittgenstein’s Tractatus attempt to construct the world out of sense-data (Russell) or elementary propositions (Wittgenstein). Both projects collapse. Behaviourism (Watson, Ryle, early Wittgenstein of the Philosophical Investigations) tries to eliminate consciousness altogether: “mind” is just intelligent behaviour. The failure of behaviourism to account for private experience leads to the identity theory (Place 1956, Smart 1959): mental states are identical with brain states. Feigl and Armstrong defend a contingent, topic-neutral identity; science will discover which neural processes are pain, which are belief.

Kripke’s Naming and Necessity (1972) delivers a seemingly fatal blow: if pain = C-fibre firing is true, it is necessarily true, but we can conceive of pain without C-fibre firing (and vice versa). The identity theorist must either embrace Leibniz’s law and deny the conceivability (type-B physicalism) or accept dualism. Functionalism (Putnam, Lewis) appears to escape the dilemma: mental states are defined by their causal roles, not their physical realisers. A state is pain if it is typically caused by tissue damage, causes avoidance behaviour, and occupies a certain node in the causal network. Martians, robots, or suitably programmed computers could have pain. Yet functionalism inherits the problems of absent qualia (Block’s Chinese nation) and inverted qualia (the inverted spectrum).

The 1980s and 1990s see an explosion of anti-physicalist arguments. Frank Jackson’s knowledge argument (Mary the colour scientist) claims that physical knowledge is incomplete without phenomenal knowledge. Chalmers’ zombie argument and conceivability argument claim that consciousness is not entailed by physical facts. Saul Kripke’s posterior necessity arguments are revived. Nagel’s “What is it like to be a bat?” (1974) and Levine’s explanatory gap (1983) articulate the intuition that no amount of third-person information captures the first-person perspective.

Representationalism (Dretske, Tye, Lycan) attempts to naturalise qualia by identifying them with tracked properties of external objects. The redness of red is the representation of a certain surface reflectance property under normal conditions. Transparency is the key datum: when we introspect experience, we seem to encounter only the objects and properties represented, not some inner screen. Yet the hard core of the hard problem remains: why does representation feel like anything at all?

Higher-order theories (Rosenthal, Lycan, Carruthers) claim a mental state is conscious when it is the object of a suitable higher-order representation. This promises to explain the difference between conscious and unconscious perception without extra qualia. Critics object that it either requires an infinite regress or posits unconscious higher-order states that are mysteriously conscious-making.

Panpsychism returns in respectable form. Galen Strawson argues that physics is entirely dispositional; something categorical must ground the dispositions, and experience is the only categorical reality we know. Russellian monism (Chalmers, Goff, Roelofs) distinguishes the structural facts described by physics from the intrinsic, proto-phenomenal properties that realise them. Consciousness at the human level is a particular organisation of these fundamental experiential properties.

Illusionism (Dennett 1988, Frankish 2016, Pereboom 2022) takes the opposite tack: phenomenal consciousness as ordinarily conceived is a myth generated by introspection. We are “filled with the illusion of immediacy”; introspection is a user-interface that misrepresents functional states as ineffable qualia. Strong illusionism predicts that once the neural mechanisms of report are fully understood, the residual mystery will evaporate.

As of late 2025, the landscape is fragmented. The majority of analytic philosophers of mind declare themselves physicalists (type-A or type-B), yet few can articulate a positive account that satisfies both the explanatory gap intuition and the demand for metaphysical closure. A growing minority—perhaps 20–25 % in recent PhilPapers surveys—embrace either Russellian monism or some form of non-reductive realism. Illusionism has gained sophisticated defenders but remains unpopular, largely because it appears to deny the one datum no one can coherently doubt: that there is something it is like to be me right now.

The Western tradition has thus moved in a great circle. From Plato’s immaterial knower to Descartes’ res cogitans, from Kant’s transcendental unity to Husserl’s pure consciousness, from Russell’s sense-data to Chalmers’ hard problem, the same intuition persists: consciousness is not just one more complicated mechanism among others; it is the condition under which mechanisms, descriptions, and theories themselves become manifest. Every attempt to reduce it to physics, function, or illusion eventually confronts the same residue: the sheer presence of experience. Whether that residue is ultimate, fundamental, or merely the limit of our current conceptual scheme remains, after two and a half millennia, the open wound at the centre of Western philosophy.

Tanmoy Bhattacharyya

29th November 2025

Fifth Lecture