Abstract
In this paper we provide a philosophical analysis of the Hard Problem of consciousness and the implications of conceivability scenarios for current neuroscientific research. In particular, we focus on one of the most prominent neuroscientific theories of consciousness, integrated information theory (IIT). After a brief introduction on IIT, we present Chalmers’ original formulation and propose our own layered view of the hard problem, showing how 2 separate issues can be distinguished. More specifically, we argue that it’s possible to disentangle a core problem of consciousness from a layered hard problem, the latter being essentially connected to Chalmers’ conceivability argument. We then assess the relation between the Hard Problem and IIT, showing how the theory resists conceivability scenarios, and how it is equipped to face up to the hard problem in its broadest acceptation.
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Both authors have contributed equally to the paper.
In this article we use interchangeably the terms “consciousness”, “experience”, “phenomenal experience”, “subjective experience”, “phenomenality”.
According to the Eleatic Principle, to exist means to have causal power. IIT further refines this ontological criterion by requiring both cause and effect power. Moreover, according to IIT’s ontology, in order to exist intrinsically, an entity must have maximally irreducible cause-effect power upon itself (Tononi 2015).
Earlier versions of IIT use the term “conceptual structure” instead of Cause-Effect Structure. This nominal change does not affect our argument in any way. The same applies with the replacement of “concepts” by “distinctions”.
PCI is an algorithm based on Transcranial Magnetic Stimulation and High Density-EEG data which allows for reliable predictions with respect to the brain’s capacity for sustaining phenomenal experience, in absence of behavioral responses, including reports. Notably, PCI has proved effective in discriminating between different states: wakefulness, dreamless sleep, dreaming, and anesthesia under different agents, such as ketamine and propofol. This is important because these states are characterized by different levels of consciousness and substantial dissimilarities in the richness and vividness of conscious contents (Massimini et al. 2010; Casali et al. 2013; Sarasso et al. 2015).
For more details on the easy problems, see Chalmers (1995/2010, 3–6).
We suspect that the conceivability argument evolved from Chalmers’ dissatisfaction with early models of consciousness that seemed ad hoc or gave an impression of fiat argumentation.
Not to mention the famous Sixth Meditation, where Descartes argues for a distinctio realis between minds and bodies by an appeal to a difference in essential properties or nature. Thus, minds and bodies fail to share all properties required by an alleged identity between them, and the well-known locus of difference is the property of extendedness and thus of divisibility. Since only bodies are extended, then, by distinctness of discernibles, the mind is distinct from the body.
The standard Hard Problem is actually the Layered Hard Problem (HP = LHP). From now on, when we mention any term of the 2, you can replace it by the other, so they are considered synonyms.
We use “materialism” and “physicalism” as synonyms, albeit they can be distinguished (Bunge 2010).
With the exception of Russellian monism (RM), if it’s truly a version of physicalism about experience.
Similar considerations apply for “partial zombies” and/or “(partial) inverts”.
We focus solely on ideal conceivability, leaving aside prima facie conceivability.
The case where the 1- and 2-intension of phenomenal terms can differ can be dealt from IIT’s perspective in the same way as the standard case presented above, so we don’t discuss it further.
In the literature, these are also known as “perfect” or “true” zombies. We believe that “functional zombies” help the reader by clarifying what we mean by that.
Like noted above, the term “conceptual structure” is synonymous to “cause-effect structure”.
Notice how, according to our reconstruction, in IIT consciousness is identical to a physical object, the cause-effect structure. However, this is radically different from standard physicalism or other kinds of reductionism. Consciousness is ontologically identical but epistemically irreducible to physical stuff, as consciousness is our starting point. Moreover, ‘physical’ in IIT is defined within the theory as ‘cause-effect power’.
Chalmers’ considerations seem to be driven by his commitment to modal rationalism, which is a version of modal monism, namely the metaphysical thesis that there is only one type of necessity/possibility that governs all of our use of modal expressions. Without discussing any of these issue in detail, we want to point out to the reader that there are working alternatives to this view. For instance, Fine (2004) argues for a modal pluralistic view, where the metaphysical necessity (which roughly corresponds to Chalmers’ broad notion of logical necessity) is irreducible to both natural or nomological necessity and normative necessity. The three types are to be considered as independent sources to which our modal expressions could be traced. Neither is analyzable in terms of the other.
Including those states that would not be observed without an intervention on the system.
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Acknowledgments
We are thankful to Giulio Tononi, Matteo Grasso and Garrett Mindt for meaningful conversation about IIT and its philosophical foundations. We also thank Jussi Jylkkä, Henry Railo, Jarno Tuominen, and other members of Antti Revonsuo’s Consciousness Research Group for helpful comments on a presentation we had at University of Turku, Finland. We are especially indebted to the audience of the 4th SILFS Postgraduate Conference, University of Urbino, Italy, and to the kind organizers who invited us to submit the paper to this journal issue. We are also thankful to 2 anonymous reviewers for important feedbacks on an earlier version of the paper.
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Chis-Ciure, R., Ellia, F. Facing up to the Hard Problem of Consciousness as an Integrated Information Theorist. Found Sci 28, 255–271 (2023). https://doi.org/10.1007/s10699-020-09724-7
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DOI: https://doi.org/10.1007/s10699-020-09724-7