‘Sentience’ sometimes refers to the capacity for any type of subjective experience, and sometimes to the capacity to have subjective experiences with a positive or negative valence, such as pain or pleasure. We review recent controversies regarding sentience in fish and invertebrates and consider the deep methodological challenge posed by these cases. We then present two ways of responding to the challenge. In a policy-making context, precautionary thinking can help us treat animals appropriately despite continuing uncertainty about their sentience. In (...) a scientific context, we can draw inspiration from the science of human consciousness to disentangle conscious and unconscious perception (especially vision) in animals. Developing better ways to disentangle conscious and unconscious affect is a key priority for future research. (shrink)

This article introduces and defends the “pathological complexity thesis” as a hypothesis about the evolutionary origins of minimal consciousness, or sentience, that connects the study of animal consciousness closely with work in behavioral ecology and evolutionary biology. I argue that consciousness is an adaptive solution to a design problem that led to the extinction of complex multicellular animal life following the Avalon explosion and that was subsequently solved during the Cambrian explosion. This is the economic trade-off problem of having to (...) deal with a complex body with high degrees of freedom, what I call “pathological complexity.” By modeling the explosion of this computational complexity using the resources of state-based behavioral and life history theory we will be able to provide an evolutionary bottom-up framework to make sense of subjective experience and its function in nature by paying close attention to the ecological lifestyles of different animals. (shrink)

For consciousness to exist, an entity must have prerequisite characteristics and attributes to give rise to it. We explore these “building blocks” of consciousness in detail in this paper, which range from perceptive to computational to meta-representational characteristics of an entity’s cognitive architecture. We show how each cognitive attribute is strictly necessary for the emergence of consciousness, and how the building blocks may be used for any entity to be classified as being conscious. The list of building blocks is not (...) limited to human or organic consciousness and may be used to classify artificial and organisational conscious entities. We further explore a list of attributes that seem intuitively necessary for consciousness, but on further investigation, are neither required nor sufficient. The building blocks do not represent a theory of consciousness but rather a meta-theory on the emergence and classification of consciousness. (shrink)

Birch, Ginsburg, and Jablonka, in an article in this issue of Biology and Philosophy, provided a much-needed condensation of their well-reasoned theory of Unlimited Associative Learning. This theory compellingly identifies the conscious animals and the time when the evolutionary transition to consciousness was completed. The authors convincingly explained their use of UAL as a “transition marker,” identified two more features by which UAL can be recognized, showed how UAL’s learning features relate to consciousness, and how investigating consciousness is analogous to (...) investigating life. My constructive criticisms are that I wish they had taken a stand on which organisms and entities are not conscious, and I feel they made too many predictions by which to test the UAL theory. That is, some of the proposed tests are unnecessary because parts of UAL are already supported by enough evidence, and other proposed tests are so ambitious as to be nearly impossible to complete. Finally, UAL has a major, detailed, sub-hypothesis that says such learning led to stress and to the evolution of mechanisms to cope with this stress; but this idea is speculative and requires the most basic testing to judge whether it could be valid. (shrink)

In this commentary I expand on the first of Noble’s illusions, the selection metaphor. Building on my work with Simona Ginsburg on the evolution of minimal consciousness, I argue that the existence of some complex sensory and motor patterns in the living world can be accounted for only through the evolution of conscious choice.

In our target article, “Learning and the evolution of conscious agents” we outlined an evolutionary approach to consciousness, arguing that the evolution of a form of open-ended, representational, and generative learning (unlimited associative learning, UAL) drove the evolution of consciousness. Our view highlights the dynamics and functions of consciousness, delineates its taxonomic distribution and suggests a framework for exploring its developmental and evolutionary modifications. The approach we offer resonates with biosemioticians’ views, but as the responses to our target article show, (...) our proposal also faces challenges and has led to suggestions that extend, develop and qualify it. Our response to the 14 varied and rich commentaries starts with the recurring and deep question raised by many of them – the relation between life and sentience. We explore this question by introducing and expanding on “vivaciousness”, a term we coined to describe the turbulent, flexible exploration-stabilization processes inherent in the living condition, as well as addressing the related concepts of Umwelt and selfhood. We then consider the question of the adequacy of unlimited associative learning (UAL) as an evolutionary transition marker (ETM) of minimal consciousness (rather than as a marker of a complex form of sentience), and the possible precursors of sentience. The engagement with these broad themes is entangled with a discussion of evolutionary transitions, constitutive emergence and the function/s of consciousness. The suggestions of our commentators, urging us to explore new concepts and new avenues of research within the framework of a richer view of evolution are then discussed. We end by briefly considering what we regard as a conceptual lacuna, which is leading to the indiscriminate use of the term “sentience” and which awaits further investigation. (shrink)

The scientific study of consciousness or subjective experiencing is a rapidly expanding research program engaging philosophers of mind, psychologists, cognitive scientists, neurobiologists, evolutionary biologists and biosemioticians. Here we outline an evolutionary approach that we have developed over the last two decades, focusing on the evolutionary transition from non-conscious to minimally conscious, subjectively experiencing organisms. We propose that the evolution of subjective experiencing was driven by the evolution of learning and we identify an open-ended, representational, generative and recursive form of associative (...) learning, which we call Unlimited Associative Learning (UAL), as an evolutionary transition marker of minimal consciousness. This evolutionary marker provides evidence that the evolutionary transition to consciousness has gone to completion and allows reverse-engineering from this learning capacity to the system that enables it – making possible the construction of a toy model of UAL. The model allows us to identify some of the key processes and structures that constitute minimal consciousness, points its taxonomic distribution and the ecological context in which it first emerged, highlights its function and suggests a framework for exploring developmental and evolutionary modifications of consciousness. We point to ways of experimentally testing the relationship between UAL and consciousness in human and in non-human animals and discuss the theoretical and ethical implications of our approach. The framework we offer allows the exploration of the evolutionary changes in agency, value systems, selective processes and goals that were involved in the transition to subjective experiencing from a perspective that resonates with the approaches of bio-semioticians. (shrink)

Birch, Ginsburg, and Jablonka suggest that Unlimited Associative Learning is a “transition marker” in the evolutionary process that produced consciousness, and organizes research by tying together a range of “hallmarks” of consciousness. I argue that the features they recognize as “hallmarks” are indeed important in the evolution of consciousness, but UAL may have a more limited role.

I concur with Merker and colleague's critiques, suggesting that hypotheses about the evolutionary function of consciousness can help address them. Brains are parallel systems that function to compute possible actions and predict outcomes. I hypothesize that a core function of consciousness per se is the global feedback of information about those actions actually executed, supporting local learning via neuronal updating.

1. 1.1. Suffering is bad. This is why, ceteris paribus, there are strong moral reasons to prevent suffering. Moreover, typically, those moral reasons are stronger when the amount of suffering at st...

Birch et. al. see their model as incompatible with higher-order-thought (HOT) theories of consciousness, on which a state is conscious if one is in some suitable way aware of that state. They see higher-order (HO) awareness as an “extra ingredient”. But since Birch et al go on to say that “[t]his is not the place for a detailed discussion of HOT theories,” they don’t address why they take HO awareness to be an extra ingredient or why HOT theorists are convinced (...) that it’s needed. In this commentary we argue that higher-order theories are a crucial for understanding consciousness. (shrink)

Peter Godfrey-Smith’s Metazoa and Joseph LeDoux’s The Deep History of Ourselves present radically different big pictures regarding the nature, evolution and distribution of consciousness in animals. In this essay review, I discuss the motivations behind these big pictures and try to steer a course between them.

In this commentary, as philosophers of evolutionary biology, we will consider the evolutionary framework used in the Target Article by: (i) emphasising the fruitfulness of the interdisciplinary approach employed; (ii) highlighting some potentially controversial aspects of the proposal; and finally (iii) outlining some ideas for further integration within the UAL framework. The critical analysis will focus on the relationship between learning and consciousness, on the assumed need for a function for consciousness, and on the type of phylogenetic demarcation introduced by (...) UAL. (shrink)

There are many theories of the functions of consciousness. How these theories relate to each other, how we should assess them, and whether any integration of them is possible are all issues that remain unclear. To contribute to a solution, this paper offers a conceptual framework to clarify the theories of the functions of consciousness. This framework consists of three dimensions: (i) target, (ii) explanatory order, and (iii) necessity/sufficiency. The first dimension, target, clarifies each theory in terms of the kind (...) of consciousness it targets. The second dimension, explanatory order, clarifies each theory in terms of how it conceives of the explanatory relation between consciousness and function. The third dimension, necessity/sufficiency, clarifies each theory in terms of the necessity/sufficiency relation posited between consciousness and function. We demonstrate the usefulness of this framework by applying it to some existing scientific and philosophical theories of the functions of consciousness. (shrink)

Sentience is the capacity to have feelings, such as feelings of pain, pleasure, hunger, thirst, warmth, joy, comfort and excitement. It is not simply the capacity to feel pain, but feelings of pain, distress or harm, broadly understood, have a special significance for animal welfare law. Drawing on over 300 scientific studies, we evaluate the evidence of sentience in two groups of invertebrate animals: the cephalopod molluscs or, for short, cephalopods (including octopods, squid and cuttlefish) and the decapod crustaceans or, (...) for short, decapods (including crabs, lobsters and crayfish). We also evaluate the potential welfare implications of current commercial practices involving these animals. (shrink)