Raphaël Millière

Introduction to the Philosophy of Consciousness


Questions about the nature, role and scientific explanation of consciousness are central to Philosophy of Mind and are raised more indirectly in the Philosophy of Cognitive Science. This lecture series aims to give undergraduate students an overview of central issues in the philosophical and scientific study of consciousness.

In particular, the aim of this lecture series is to help students think about critical questions regarding what consciousness is, its place in the natural world, how it relates to physical processes, and how it can be scientifically investigated.

Lecture 1. What is consciousness?

This first lecture starts with a fundamental question for the study of consciousness: how should we define it? As David Chalmers puts it in The Conscious Mind, there seems to be nothing more familiar to us than consciousness; and yet the task of defining it presents a remarkable challenge.

Students will be invited to reflect on the uses of the term ‘consciousness’ and its cognates in ordinary language. Creatures such as living organisms are the sort of things that are typically said to be conscious. This can be said in a dispositional sense, to ascribe the capacity for consciousness to certain creatures - for example when we wonder whether rats or octopuses are conscious. But this dispositional use of the term must be grounded in an understanding of what it is for a creature to be conscious at a specific time. To elucidate this point one may appeal to the intuitive difference between global states of a creature: consciousness is the sort of thing that is lacking when one is in a coma, and present when one is fully awake.

However, consciousness is also predicated of specific mental states, such as beliefs, desires and perceptions may be conscious. What does it mean for a mental state to be conscious, as opposed to unconscious? Suppose that you see a blue sky; this perception may be said to be conscious in so far as it has a certain qualitative feel. In Thomas Nagel’s influential formulation, there is something it is like for you to see the blue sky.

The lecture will conclude with a reflection on the apparent circularity in these definitions of consciousness, which rely on paraphrases and examples. This may not be an issue, however, if we can agree on the phenomenon targeted by these paraphrases and examples in our own subjective experience.

Lecture 2. The hard problem of consciousness

This lecture discusses the daunting challenge of explaining how a physical information-processing system such as the human brain may give rise to conscious experience. This challenge has been called the ‘hard problem’ of consciousness by David Chalmers, by contrast with so-called ‘easy problems’ concerned with the explanation of various cognitive functions. The difficulty presented by the hard problem stems from the fact that there seems to be an unbridgeable explanatory gap between consciousness and the physical world. The prospect of reducing conscious experience to physical processes in the brain appears to be hampered by this gap.

The lecture will illustrate the strength of the hard problem with two influential arguments against the reduction of consciousness to the physical: Chalmers’ argument from the conceivability of philosophical zombies, and Franck Jackson’s knowledge argument about Mary the colour scientist. Students will be encouraged to assess both of these arguments critically, through the discussion of the soundness of each of their premises. This will lead us to consider rebuttals of these arguments proposed by Daniel Dennett in defense of the claim that consciousness is reducible to physical mechanisms.

Finally, the lecture will conclude with a brief overview of the two main philosophical accounts of the place of conscious experience in the physical world, namely dualism and physicalism, and will consider their respective merits in light of our discussion of the hard problem.

Lecture 3. Towards a science of consciousness

This lecture will discuss how consciousness may be scientifically studied. We will start from the apparent discrepancy between the third-person methodology of scientific inquiry and the first-person nature of consciousness. Indeed, the collection of data about behaviour and brain processes may only inform a scientific investigation of consciousness if it can be linked to some form of evidence regarding the subjects’ subjective experience.

The most obvious way to do so is to rely on the subjects’ reports about their own experience, but this raises two methodological issues. Firstly, can we trust people’s reports about their experience, given that introspection appears to be fallible? We will see that this problem may be mitigated by designing experiments that do not rely on direct verbal reports. Secondly, are conscious experiences always accessible for report? We will consider Ned Block’s argument that the current scientific practice in consciousness studies has been targeting the wrong phenomenon, because it relies on the availability of mental contents for verbal report and use in reasoning and action (what Block calls ‘access consciousness’), rather than the subjects’ first-person experience per se (what he calls ‘phenomenal consciousness’).

In the final part of the lecture, we will consider how the scientific study of consciousness can progress without tackling the hard problem head on, by searching for the neural correlates of consciousness (what Chalmers called the ‘mapping problem’, also provocatively dubbed the ‘real problem’ of consciousness by neuroscientist Anil Seth). We will discuss what a neural correlate of consciousness is, and how neuroscientists may proceed to uncover such correlates.

Lecture 4. Levels and contents of consciousness

The final lecture will draw on insights from the first three lectures to explore two interdisciplinary hot topics in consciousness research: are there levels of consciousness? And how rich are the contents of consciousness? This lecture will illustrate how philosophers and scientists can join forces to address such questions.

The notion of a level of consciousness is a key construct in the science of consciousness. It derives from the clinical literature on so-called ‘disorders of consciousness’, such as the vegetative states (VS) or the minimally conscious state (MCS). The idea behind this notion is that it should be possible in principle to order such global states of consciousness along a single graded scale, such that an individual could be said to be more or less conscious than another at a given time (for example, MCS patients will be said to have a higher level of consciousness than VS patients). In recent years, scientists have extended the use of the notion of conscious levels beyond clinical practice, to inform the project of creating a ‘consciousness meter’, namely a method to measure the level of consciousness of any individual. The first part of this lecture will discuss the philosophical assumptions behind this project. It will be suggested that ordering global states of consciousness along a single dimension might be problematic.

Another lively debate within consciousness research regards the richness or ‘bandwidth’ of consciousness in ordinary experience. Were you conscious of the soles of your feet in your shoes before reading this sentence? What about the background noise in your environment? Philosophers and scientists have tried to address this controversial issue in recent years through a variety of methods. The second part of the lecture will illustrate how conceptual and empirical approaches offer complementary perspectives on this topic.