Abstract
According to what Birch (2022) calls the theory-heavy approach to investigating nonhuman-animal consciousness, we select one of the well-developed theories of consciousness currently debated within contemporary cognitive science and investigate whether animals exhibit the neural structures or cognitive abilities posited by that theory as sufficient for consciousness. Birch argues, however, that this approach is in general problematic because it faces what he dubs the dilemma of demandingness—roughly, that we cannot use theories that are based on the human case to assess consciousness in nonhuman animals and vice versa. We argue here that, though this dilemma may problematize the application of many current accounts of consciousness to nonhuman animals, it does not challenge the use of standard versions of the higher-order thought theory (“HOTT”) of consciousness, according to which a creature is in a conscious mental state just in case it is aware of being in that state via a suitable higher-order thought (“HOT”). We show this in two ways. First, we argue that, unlike many extant theories of consciousness, HOTT is typically motivated by a commonsense, and more importantly, neutral condition on consciousness that applies to humans and animals alike. Second, we offer new empirical and theoretical reasons to think that many nonhuman animals possess the relevant HOTs necessary for consciousness. Considering these issues not only reveals the explanatory power of HOTT and some of its advantages over rival accounts, but also enables us to further extend and clarify the theory.
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Notes
Henceforth we typically drop the ‘nonhuman’ qualifier, and refer to such creatures as ‘animals’.
On various uses of ‘consciousness’ and related expressions, see, e.g., Berger & Brown, 2021: Sect. 2. Going forward, uses of such expressions refer to phenomenal consciousness, unless otherwise specified.
For an overview of such theories, see, e.g., Seth & Bayne, 2022.
Although the objection is often framed in terms of human infants too, we focus here on the case of nonhuman animals, though what we say here arguably extend to infants as well.
For a recent defense of HOTT, including replies to many objections, see, e.g., Berger & Brown, 2021.
We acknowledge that some of the evidence of nonconscious perception has recently been challenged (see, e.g., Phillips, 2021). Some urge that what might seem to be evidence for subliminal perception is instead evidence for either for weakly conscious states that are simply unreported due to stringent criteria for such responses or for nonmental states that are incapable of driving genuine action. But skepticism about nonconscious mentality is questionable for several reasons that we cannot explore here (but see, e.g., Berger & Mylopoulos, 2021).
Lycan has since given up HOP theory; see, e.g., Sauret & Lycan, 2014.
Some theories, such as IIT, may also have organism-neutral motivations. But the conditions for consciousness on such theories are thereby typically so undemanding that they face not the necessity, but the sufficiency, horn of the dilemma. On typical interpretations of IIT, for example, the theory is highly undemanding insofar as it attributes consciousness not only to all nonhuman animals, but to anything that exhibits a sufficiently high degree of informational integration, including simple nonliving systems such as logic gates (e.g., Tononi & Koch, 2015). So, while HOTT may not have an advantage over such theories in this connection, it does have an advantage insofar as it does not face the sufficiency horn, as we argue shortly.
We thank Richard Brown for raising this objection to us.
Our account nonetheless differs from Gennaro’s in certain ways. Perhaps most saliently, Gennaro defends both a version of concept nativism, on which some concepts are innate, and a form of conceptualism, on which experiential states such as perceptual states are, like ordinary thoughts, conceptual states too. But we remain neutral here regarding both nativism and conceptualism. Notice, however, that HOTT does not presuppose either. Though, on HOTT, HOTs are conceptual as well as necessary and sufficient for consciousness, HOTs are themselves also typically theorized to be seldom conscious (see, e.g., Rosenthal, 2005, p. 9). Rather, they are the states in virtue of which perceptual or other states are conscious. HOTT is thus compatible with perceptual states’ being nonconceptual in some way (for a version of nonconceptualism about perception, see, e.g., Dretske, 1995). It is thus reasonable to think that all concepts might be acquired via a learning process involving perception that is both nonconceptual and nonconscious (for a similar type of account, see, e.g., Rosenthal, 2005, pp. 203ff).
To be clear, we are not assuming an inferentialist or conceptual-role account of the nature of conceptual content on which concepts’ contents are individuated by those concepts’ roles in inference—that is, in terms of their inferential connections to other concepts (e.g., Harman, 1987). Our account of ease of concept acquisition is consistent with virtually any theory of the metaphysics of content, such as varieties of teleosemantics on which a concept’s content depends only on its standing in the appropriate evolutionarily developed tracking relation to what it represents (e.g., Neander, 2006). It may be that concepts are variably difficult to acquire insofar as they require possessing different ranges of concepts, though possessing those different ranges of concepts is what puts a concept into the relevant tracking relation, thereby determining that concept’s content.
One might think that there is good evidence that nonhumans can be and often are aware of cognitive states—namely, in cases of animal metacognition (see, e.g., Beran, 2019; we thank Robert van Gulick for this objection). But there are several things to say. First, we are not committed to the view that no nonhuman animals possess conscious thoughts. Indeed, we believe HOTT would be even more welcomed if it attributed types of consciousness more widely. Secondly, however, it is not obvious that metacognition involves the deployment of concepts of other mental states. It could be, for example, that the metacognitive assessment of a state as being accurate or inaccurate operates nonconceptually or subpersonally (e.g., Lau, 2022).
Of course, such a three-fold distinction requires an account of the nature of personal-level mental states independent of consciousness. But many theories within the metaphysics of mind, such as varieties of identity theory or functionalism, are compatible with the individuation of mental states in terms of their neural bases or causal roles, which can occur outside of consciousness.
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We thank Richard Brown, Alex Kiefer, Rocco Gennaro, Joseph Gottlieb, Claudia Passos, David Pereplyotchik, Adriana Renero, David Rosenthal, Dan Shargel, and the audience at the 2023 Science of Consciousness Conference in Taormina, Sicily for their helpful discussions of or comments on this material. This work was supported by a Lycoming College Professional Development Grant.
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Berger, J., Mylopoulos, M. HOTT and heavy: higher-order thought theory and the theory-heavy approach to animal consciousness. Synthese 203, 98 (2024). https://doi.org/10.1007/s11229-024-04529-8
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DOI: https://doi.org/10.1007/s11229-024-04529-8