I will extend Seth’s argument as follows:

1. 1. Creature consciousness provides the medium for phenomenally conscious states.

2. 2. The medium for phenomenally conscious states depends on specific neurobiophysical properties that are not medium flexible in the way required by computational functionalism.

3. Conclusion: Therefore, computational functionalism fails.

By “creature consciousness,” I don’t mean mere wakefulness or behavioral responsiveness to stimuli (cf. Rosenthal, Reference Rosenthal2005); I mean a range of global brain states such that, when an organism is in them, the organism instantiates phenomenally conscious states, whether during wakefulness, sleep, or any other state (cf. Piccinini, Reference Piccinini2007).

By “medium” or “substrate” for phenomenally conscious states, I don’t mean merely a background enabling condition without which the organism cannot function – whether consciously or unconsciously. Rather, I mean a constitutive enabling condition that helps make the difference between consciousness and unconsciousness (cf. McKilliam, Reference McKilliam2020, Reference McKilliam2024).

By “neurobiophysical properties,” I mean some combination of neural, biological, chemical, and physical properties constitutively relevant to the substrate of conscious experiences. We don’t know precisely what all such properties are, and they may not require being alive or even having a nervous system, but we know enough to conclude that they are unlikely to be medium flexible in the way required by computational functionalism.

The empirical evidence for the necessity of creature consciousness comes primarily from sleep research. Sleep researchers distinguish between wakefulness and four sleep stages, N1-N3 plus REM sleep, which exhibit different EEG (electroencephalogram) signatures. A full account would include states such as anesthesia and coma, but the most helpful states are relatively easy to awaken from to get reliable information on what it was like to be in them.

Different EEG signatures indicate different modes of neural oscillation and synchronization. The ability to be awakened shows that nervous systems retain some capacity for information processing during all phases of sleep. Yet wakefulness and different sleep stages allow very different sorts of conscious experiences. When awakened from REM sleep, people typically report vivid dreams; when awakened from N1 and N2, they typically report thoughts or sensory experiences; when awakened from N3, they typically report no experiences. This suggests that phenomenal consciousness is not binary but exists on a continuum that depends on the underlying type of creature consciousness, which in turn depends on the underlying neurobiophysical state. Humans can be conscious only when their brains occupy certain global states – primarily normal wakefulness and REM sleep, but also N1 and N2. During N3 – slow-wave, deep sleep – the capacity for consciousness appears to be absent (e.g., Hobson, Reference Hobson2009). This pattern suggests that whether humans can experience different kinds of phenomenally conscious states depends critically on the global state of their brain – what I call creature consciousness.

The neural correlates of consciousness research program (Koch et al., Reference Koch, Massimini, Boly and Tononi2016) has traditionally focused on identifying the specific neural mechanisms and states underlying particular conscious experiences. The necessity of creature consciousness suggests we must also identify what might be called the “enabling conditions of consciousness” (ECCs) – the background global brain states that make any conscious experience possible.

The second component of my argument concerns the neurobiophysical specificity of creature consciousness. A combination of neurobiophysical properties provides the medium for phenomenal consciousness without determining specific experiences. The brainstem reticular activating system, for instance, plays a crucial role in maintaining arousal states that enable consciousness (Steriade, Reference Steriade2000; cf. Merker, Reference Merker2007). Similarly, the intralaminar thalamic nuclei contribute to the substrate that supports conscious access while remaining largely content-neutral (Newman, Reference Newman1995).

These systems’ primary function involves transitioning between and sustaining global brain states either by bathing the brain in precise mixtures of specific neurotransmitters (including acetylcholine, norepinephrine, serotonin, histamine, and GABA) or by amplifying or dampening neural signals (Jones, Reference Jones2005; Brown et al., Reference Brown, Basheer, McKenna, Strecker and McCarley2012). Recent high-resolution neuroimaging studies confirm the importance of specific networks involving the brainstem, hypothalamus, basal forebrain, thalamic gating mechanisms, and cortical integration networks in sustaining the arousal states necessary for consciousness (Laureys, Reference Laureys2005; Shine et al., Reference Shine, Lewis, Garrett and Hwang2023; Edlow et al., Reference Edlow, Olchanyi, Freeman, Li, Maffei, Snider, Zöllei, Iglesias, Augustinack, Bodien, Haynes, Greve, Diamond, Stevens, Giacino, Destrieux, van der Kouwe, Brown, Folkerth, Fischl and Kinney2024). Partly due to such arousal, large portions of brain tissue create their own rhythmic balance of excitation and inhibition and, as a result, oscillate and synchronize at different frequencies during different kinds of global states. Different patterns of oscillation and synchronization, in turn, contribute to different kinds of creature consciousness and play fundamental cognitive roles (e.g., Buzsáki & Draguhn, Reference Buzsáki and Draguhn2004). Creature consciousness thus appears to depend on a complex balance of neurological, molecular, and biophysical factors. The precise balance and interaction of these systems determine whether a brain can support conscious experience at all and what kind of conscious experience it can have.

These considerations undermine computational functionalism, the view that mental states are defined by their computational roles and are therefore realizable in any suitable computational medium (Piccinini, Reference Piccinini2020, Ch. 14). If creature consciousness depends on specific neurobiophysical properties that constitute a specific medium for phenomenally conscious states, then conscious states are not medium-flexible, and computational functionalism fails as a theory of consciousness.

This suggests that one of three alternative views holds: Seth’s biological naturalism, some form of nonbiological yet noncomputational functionalism, or some version of what Anderson and Piccinini (Reference Anderson and Piccinini2024) call qualitativism – the view that consciousness depends at least in part on specific (macro)physical qualities rather than purely functional or computational properties.

Rejecting computational functionalism does not require rejecting the role of neural computation in conscious experience (cf. Chirimuuta, Reference Chirimuuta2024). Various forms of neural computation occur while organisms are creature conscious, and some of them seem to contribute to the content and structure of conscious experience. These computations appear to be enabled and constrained by the neurobiophysical substrate of creature consciousness rather than being sufficient for consciousness on their own.

In conclusion, by distinguishing between creature consciousness and phenomenal consciousness, we can articulate more precisely why consciousness appears to depend on specific neurobiophysical properties of living systems. This account suggests that genuine artificial consciousness would require not just more sophisticated computation but technologies that can recreate specific neurobiophysical conditions – a prospect that remains elusive given our currently limited understanding.