Philosophy · Year 12 · Metaphysics of Mind · Summer Term

The Mind-Body Problem and Substance Dualism

Introduce the central problem of how the mind relates to the body and examine Descartes' argument that the mind is a distinct, non-physical substance.

TL;DR:Challenge your students to move beyond Descartes and explore a more modern form of dualism that doesn't require a 'ghost in the machine'. This topic introduces property dualism through the vivid and highly debatable 'Mary's Room' thought experiment.

• National Curriculum Attainment Targets
• AQA A-Level Philosophy: Section 4.2 - Metaphysics of Mind - What do we mean by 'mind'? - Substance Dualism

About This Topic

This topic delves into one of the most significant modern responses to the mind-body problem: property dualism. Positioned within the A-Level Philosophy curriculum, particularly for units on Metaphysics of Mind, this serves as a critical evaluation of physicalism. While students may have already encountered substance dualism via Descartes, which posits two distinct types of substance (mental and physical), property dualism offers a more nuanced view. It argues that there is only one kind of substance, physical substance, but that this substance can have two irreducibly different kinds of properties: physical properties (like mass and charge) and mental properties (like the subjective experience of seeing red or feeling pain).

The core of this topic revolves around the challenge that 'qualia', the intrinsic, non-physical qualities of experience, pose to physicalist theories of mind. The central argument explored is Frank Jackson's 'knowledge argument', famously illustrated by the 'Mary's Room' thought experiment. Students will be required to not only understand and explain this argument but also to critically analyse its premises and evaluate powerful objections, such as the 'ability knowledge' response. This encourages a sophisticated level of philosophical analysis, moving beyond simple dichotomies to engage with the subtle yet profound difficulties in accounting for consciousness within a purely physical framework.

Key Questions

1. Explain Descartes' conceivability and indivisibility arguments for substance dualism.
2. Analyse the problem of interaction: how can an immaterial mind cause changes in a physical body?
3. Evaluate whether the mind is better understood as a substance or as a set of properties.

Learning Objectives

• Explain the concept of qualia and its significance in the mind-body debate.
• Analyse the structure and key premises of Frank Jackson's knowledge argument.
• Evaluate the strengths and weaknesses of the knowledge argument, including key objections such as the 'ability knowledge' response.
• Distinguish clearly between substance dualism and property dualism.
• Articulate the challenge that property dualism poses to physicalist theories of mind.

Key Vocabulary

Property Dualism	The view that there is only one kind of substance (physical), but that it has two distinct kinds of properties: physical and non-physical mental properties (like qualia).
Qualia	The subjective, qualitative, and intrinsic properties of conscious experience; what it is like to have a certain experience, such as seeing the colour red or feeling a pain.
Physicalism	The metaphysical thesis that everything that exists is physical, or supervenes on the physical. In philosophy of mind, it holds that the mind is not a separate substance but is identical to physical processes in the brain.
Knowledge Argument	An argument against physicalism, most famously proposed by Frank Jackson, which claims that if a brilliant neuroscientist (Mary) knows all the physical facts about colour vision but has never seen colour, she learns something new when she first sees it. This new knowledge, it is argued, is of a non-physical fact.
Mary's Room	The thought experiment used to illustrate the knowledge argument, involving a neuroscientist named Mary who is confined to a black-and-white room but knows everything physical about colour.
Ability Knowledge	A response to the knowledge argument which claims that what Mary gains is not new factual knowledge ('knowledge-that'), but rather a new ability or know-how ('knowledge-how'), such as the ability to recognise and imagine colours.

Watch Out for These Misconceptions

Common Misconception

Property dualism is the same as substance dualism.

What to Teach Instead

Substance dualism (like Descartes') claims there are two fundamental kinds of 'stuff' in the universe: physical substance and mental substance. Property dualism claims there is only one kind of substance (physical), but it has two distinct kinds of properties (physical and mental).

Common Misconception

The knowledge argument proves that God or a soul exists.

What to Teach Instead

The knowledge argument is specifically about the nature of conscious experience and its properties. It argues against physicalism but does not, on its own, provide evidence for a non-physical soul or a deity; it only concludes that some properties are non-physical.

Common Misconception

If Mary learns something new, it means physicalism is completely wrong about everything.

What to Teach Instead

The argument targets a specific claim of physicalism: that all knowledge is physical knowledge. A physicalist could respond by modifying their position, for example, by arguing that Mary gains a new ability or a new perspective, not a new piece of factual information about the world.

Active Learning Ideas

Socratic Seminar

Mary's Room Debate

Divide the class into two groups. One group argues that Mary learns something new upon leaving the room, supporting property dualism. The other group argues she learns nothing new (or only gains 'ability knowledge'), defending physicalism. Each side prepares opening statements, rebuttals, and a conclusion.

45 min·Whole Class

Socratic Seminar

Qualia Inventory

In pairs, students create a list of five different 'qualia' they have experienced. They must then attempt to write a purely physical, scientific description of that experience, highlighting where and why the description fails to capture the subjective character of the experience.

20 min·Pairs

Socratic Seminar

Argument Reconstruction

Provide students with a jumbled version of the premises and conclusion of the knowledge argument. In small groups, they must reconstruct the argument into a logically valid form (P1, P2, C) and then identify which premise a physicalist is most likely to attack.

25 min·Small Groups

Real-World Connections

• Artificial Intelligence: Discusses whether a sufficiently complex AI could ever be genuinely conscious and have qualia, or if it would only ever be a 'philosophical zombie' simulating conscious behaviour.
• Neuroscience and Medicine: Relates to the 'hard problem of consciousness' and the challenge of identifying and measuring subjective experience in patients, for example, in determining levels of consciousness in coma patients.
• Animal Ethics: The debate over whether animals possess qualia and have subjective experiences is central to arguments about animal rights and welfare.
• Sensory Perception: Connects to the study of sensory substitution devices, where, for example, blind individuals can learn to 'see' via sound or touch, raising questions about the nature of the qualia they experience.

Assessment Ideas

Peer Assessment

An essay question such as 'Assess the claim that the knowledge argument successfully refutes physicalism.' This allows students to demonstrate understanding, analysis, and evaluation.

Exit Ticket

An 'exit ticket' where students must write down, in their own words, the strongest objection to the knowledge argument and why they think it is (or is not) successful.

Quick Check

Provide students with a checklist of key concepts and arguments from the topic. They can rate their confidence level (e.g., red, amber, green) for each, identifying areas for revision.

Frequently Asked Questions

What is the difference between property dualism and epiphenomenalism?

Epiphenomenalism is a specific type of property dualism. All epiphenomenalists are property dualists, but not all property dualists are epiphenomenalists. Epiphenomenalism holds that mental properties are caused by physical processes in the brain but have no causal effects on the physical world themselves; they are like the steam from a train that doesn't power the engine.

How could a property dualist respond to the problem of interaction?

This is a major challenge. Some property dualists, known as 'interactionists', argue that non-physical mental properties can and do have a causal effect on the physical brain, though explaining the mechanism is difficult. Others adopt epiphenomenalism, denying that mental properties have any causal power, thus avoiding the problem of interaction but creating new problems, like explaining why we can talk about our mental states.

Isn't the 'Mary's Room' argument just an intuition pump that doesn't prove anything?

Critics, like Daniel Dennett, argue exactly this. They claim thought experiments like Mary's Room are designed to appeal to our intuitions but can be misleading. However, proponents argue that it's a valid philosophical argument that clarifies the implications of physicalism and forces us to confront what it would mean if all facts were physical facts.