Lecture 2: The Nature of Persons: Dualism vs. Physicalism

What this lecture covers

Before asking whether we survive death, the lecture answers an objection that the question itself is confused: if death just means the end of life, then asking about 'life after death' seems as silly as asking what's left on a plate after you've eaten everything. Kagan reframes the question more carefully in terms of surviving the death of the body, and shows that this version is a genuine, open question.

The lecture then turns to the question that determines the answer: what kind of thing is a person in the first place? It lays out the two main positions the course will keep returning to, dualism and physicalism, and previews the sub-questions about the soul that later lectures will address.

Key ideas

• The 'trivial objection': defining death as 'the end of life' makes 'is there life after death' sound self-answering, but this rests on an ambiguity about what 'my death' refers to.
• Death of the body: Kagan resolves the ambiguity by defining death, for this course, as the death of the body (a sequence of physical events, labeled B1 through Bn), which leaves open whether I continue to exist afterward.
• Dualism: the view that a person consists of a body and an immaterial soul, distinct from the body, which houses consciousness and thought.
• Physicalism: the view that a person is just a body, an unusually capable physical object that can think, plan, communicate and feel, with nothing immaterial involved.
• Interactionist dualism: the common version of dualism holds that body and soul causally affect each other in both directions, not that they are fully independent.
• Three separate questions about the soul: whether it exists, whether it survives bodily death, and whether it exists forever (immortality) are logically distinct and need separate arguments.
• Idealism set aside: the view that only minds exist is mentioned as a logical possibility but excluded from the course's focus.

Walkthrough

Reframing 'is there life after death' (0:01)

Kagan opens by explaining that answering whether we survive death requires first knowing what a person is and what it means to survive at all. He then presents an objection, drawn partly from a reading by Jay Rosenberg, that the whole question is trivially confused because death just means the end of life.

Death of the body (7:15)

To rescue the question, Kagan sketches (admittedly speculatively) the physical process of dying, from oxygen deprivation to cellular breakdown, and calls this sequence 'bodily death.' He then reformulates the real question as: might I still exist after the death of my body? This version is not trivially answered and becomes the working definition of 'my death' for the rest of the course.

Two views of what a person is (14:23)

The lecture introduces dualism (a person is a body plus an immaterial soul) and physicalism (a person is just a body), noting a third logical option, idealism, that the course sets aside. It explains why, for the possibility of surviving death to make sense under dualism, the person must strictly be identified with the soul rather than the soul-body combination.

Interactionist dualism and the soul's fate (21:32)

Kagan details the two-way causal connection dualists usually posit between body and soul, and separates three distinct questions: does the soul exist, does it survive bodily death, and is it immortal. He argues, against a student's suggestion, that an immaterial soul is not automatically immune to destruction by physical processes, since interactionist dualism already allows the body to affect the soul.

The physicalist alternative (39:53)

The lecture closes by describing physicalism in more detail: a person is a body, but an extraordinarily capable one, distinguished from a piece of chalk or a cell phone by its ability to think, plan, feel and communicate.

Before you watch

• This lecture builds directly on Lecture 1's overview of the course's two halves (metaphysics, then value theory).
• Some familiarity with the terms 'soul,' 'dualism' and 'physicalism' as used in everyday discussion is helpful but not required.

Check your understanding

1. Why does defining death as 'the end of life' make the question 'is there life after death' seem trivially unanswerable, and how does Kagan avoid that trap?
2. What is the difference between asking whether the soul exists and asking whether it survives the death of the body?
3. Why must a dualist say the person is 'strictly speaking' the soul rather than the soul-body pair?
4. What does 'interactionist dualism' claim about the relationship between body and soul, and why does Kagan think it complicates the claim that souls can't be destroyed by physical processes?