Philosophical Topics

The best empirically grounded theory of first-personal phenomenal consciousness is global workspace theory. This, combined with the success of the phenomenal-concept strategy, means that consciousness can be fully reductively explained in terms of globally broadcast representational content. So there are no qualia (and there is no mental paint). As a result, the question of which other creatures besides ourselves are phenomenally conscious is of no importance, and doesn’t admit of a factual answer in most cases. What is real, and what does matter, is a multidimensional similarity space of functionally organized minds.

Peter Carruthers has recently argued for a surprising conditional: if a global workspace theory of phenomenal consciousness is both correct and fully reductive, then there are no substantive facts to discover about phenomenal consciousness in nonhuman animals. I present two problems for this conditional. First, it rests on an odd double-standard about the ordinary concept of phenomenal consciousness: its intuitive non-gradability is taken to be unchallengeable by future scientific developments, whereas its intuitive determinacy is predicted to fall by the wayside. Second, it relies on dismissing, prematurely, the live empirical possibility that phenomenal consciousness may be linked to a core global broadcast mechanism that is (determinately) shared by a wide range of animals. Future developments in the science of consciousness may lead us to reconsider the non-gradability of phenomenal consciousness, but they are unlikely to lead us to accept that there are no facts to discover outside the paradigm case of a healthy adult human.

The question “are garden snails conscious?” or equivalently “is there something it’s like to be a garden snail?” admits of three possible answers: yes, no, and denial that the question admits of a yes-or-no answer. All three answers have some antecedent plausibility, prior to the application of theories of consciousness. All three answers retain their plausibility after the application of theories of consciousness. This is because theories of consciousness, when applied to such a different species, are inevitably question-begging and rely crucially on dubious extrapolation from the introspections and verbal reports of a single species.

We have various everyday measures for identifying the presence of consciousness, such as the capacity for verbal report and the intentional control of behavior. However, there are many contexts in which these measures are difficult (if not impossible) to apply, and even when they can be applied one might have doubts as to their validity in determining the presence/absence of consciousness. Everyday measures for identifying consciousness are particularly problematic when it comes to ‘challenging cases’—human infants, people with brain damage, nonhuman animals, and AI systems. There is a pressing need to identify measures of consciousness that can be applied to challenging cases. This paper explores one of the most promising strategies for identifying and validating such measures—the natural-kind strategy. The paper is in two broad parts. Part I introduces the natural-kind strategy, and contrasts it with other influential approaches in the field. Part II considers a number of objections to the approach, arguing that none succeeds.

This paper addresses what we consider to be the most pressing challenge for the emerging science of consciousness: the measurement problem of consciousness. That is, by what methods can we determine the presence of and properties of consciousness? Most methods are currently developed through evaluation of the presence of consciousness in humans and here we argue that there are particular problems in application of these methods to nonhuman cases—what we call the indicator validity problem and the extrapolation problem. The first is a problem with the application of indicators developed using the differences between conscious and unconscious processing in humans to the identification of other conscious vs. nonconscious organisms or systems. The second is a problem in extrapolating any indicators developed in humans or other organisms to artificial systems. However, while pressing ethical concerns add urgency to the attribution of consciousness and its attendant moral status to nonhuman animals and intelligent machines, we cannot wait for certainty and we advocate the use of a precautionary principle to avoid causing unintentional harm. We also intend that the considerations and limitations discussed in this paper can be used to further analyze and refine the methods of consciousness science with the hope that one day we may be able to solve the measurement problem of consciousness.

Affective experience in nonhuman animals is of great interest for both theoretical and practical reasons. This paper highlights research by the psychologists Anthony Dickinson and Bernard Balleine which provides particularly good evidence of conscious affective experience in rats. This evidence is compelling because it implicates a sophisticated system for goal-directed action selection, and demonstrates a contrast between apparently conscious and unconscious evaluative representations with similar content. Meanwhile, the evidence provided by some well-known studies on pain in nonhuman animals is much less convincing. This comparison may offer lessons for the future study of animal consciousness.

Identifying which nonhuman animal species are capable of feeling pain is important both for understanding pain mechanisms more generally and for informing animal welfare regulations, particularly in genera that are not yet widely protected. A common way to try to provide evidence of pain experiences is through behavioral indicators. In this paper I use a very simple interventionist approach to experimentation, and the contrast case provided by C. elegans, to argue that behavioral indicators commonly used for identifying pain in nonhuman animals are much less robust than typically presented. Indeed, I argue that many behavioral indicators of pain are invalid as they are currently described. More positively, this analysis makes it possible to identify what valid criteria might look like, and where relevant, to identify existing evidence related to them. Based on this I propose that the best way to make progress on questions around animal pain is to clearly ally them with questions about animal consciousness more generally, and to productively use conceptual and empirical work in both areas to develop more theoretically defensible behavioral indicators.

Post-Traumatic Stress Disorder (PTSD) is a mental health condition in which the experience of a traumatic event causes a series of psychiatric and behavioral symptoms such as hypervigilance, insomnia, irritability, aggression, constricted affect, and self-destructive behavior. This paper investigates two case studies to argue that the experience of PTSD is not restricted to humans alone; we have good epistemic reason to hold that some animals can experience genuine PTSD, given our current and best clinical understanding of the disorder in humans. I will use this evidence to argue for two claims. First, because the causal structure of PTSD plausibly requires reference to a traumatic conscious experience in order to explain subsequent behaviors, the fact that animals can have PTSD provides new evidence for animal consciousness. Second, the discovery of PTSD in animals puts pressure on accounts which hold that animal behavior can be fully explained without reference to subjective experience.

Most people will grant that we bear special moral obligations toward at least some nonhuman animals that we do not bear toward inanimate objects like stones, mountains, or works of art (however priceless). These moral obligations are plausibly grounded in the fact that many if not all nonhuman animals share important psychological states and capacities with us, such as consciousness, suffering, and goal-directed behavior. But which of these states and capacities are really critical for a creature’s possessing moral status, and how can we determine which animals do in fact have them? In this paper, I examine three main approaches to answering these questions. First are what I term consciousness-based approaches that tackles these questions by first asking which animals are conscious. Second are affective-state approaches that focus on identifying behavioural and physiological signatures of states like pain, fear, and stress. Finally, I consider what I call preference-based approaches whose focus is on the question of which organisms have robust motivational states. I examine the prospects and challenges—both theoretical and empirical—faced by these seemingly contrasting methodologies. I go on to suggest that there are reasons why, despite challenges, we should be robustly committed to the project of identifying psychological grounds of moral status. I conclude by suggesting we should also take seriously the idea of pluralism about moral status, according to which each of these approaches might be capable of providing independent grounds for moral consideration.

In evolution, large-scale changes that involve the origin of complex new traits occur gradually, in a broad sense of the term. This principle applies to the origin of subjective or felt experience. I respond to difficulties that have been raised for a gradualist view in this area, and sketch a scenario for the gradual evolution of subjective experience, drawing on recent research into early nervous system evolution.

Recent debates about the biological and evolutionary conditions for sentience have generated a renewed interest in fine-grained functionalism. According to one such account advanced by Peter Godfrey-Smith, sentience depends on the fine-grained activities characteristic of living organisms. Specifically, the scale, context and stochasticity of these fine-grained activities. One implication of this view is that contemporary artificial intelligence (AI) is a poor candidate for sentience. Insofar as current AI lacks the ability to engage in such living activities it will lack sentience, no matter what its coarse-grained functions. In this paper, we review the case for fine-grained functionalism and show that there are contemporary machines that fulfil the fine-grained functional criteria identified by Godfrey-Smith, and thus are candidates for sentience. Molecular machines such as Brownian computers are analogous to metabolic activity in their scale, context and stochasticity, and can serve as the basis of AI. Molecular computation is a promising candidate for artificial sentience according to contemporary philosophical accounts of sentience.

The extended mind thesis prompted philosophers to think about the different shapes our minds can take as they reach beyond our brains and stretch into new technologies. Some of us rely heavily on the environment to scaffold our cognition, reorganizing our homes into rich cognitive niches, for example, or using our smartphones as swiss-army knives for cognition. But the thesis also prompts us to think about other varieties of minds and the unique forms they take. What are we to make of the exotic distributed nervous systems we see in octopuses, for example, or the complex collectives of bees? In this paper, I will argue for a robust version of the extended mind thesis that includes the possibility of extended consciousness. This thesis will open up new ways of understanding the different forms that conscious minds can take, whether human or nonhuman. The thesis will also challenge the popular belief that consciousness exists exclusively in the brain. Furthermore, despite the attention that the extended mind thesis has received, there has been relatively less written about the possibility of extended consciousness. A number of prominent defenders of the extended mind thesis have even called the idea of extended consciousness implausible. I will argue, however, that extended consciousness is a viable theory and it follows from the same ‘parity argument’ that Clark and Chalmers (1998) first advanced to support the extended mind thesis. What is more, it may even provide us with a valuable paradigm for how we understand some otherwise puzzling behaviors in certain neurologically abnormal patients as well as in some nonhuman animals.