Swinburne’s defense of dualism

PHIL 20208
Jeff Speaks

November 2, 2006

1 The problem of duplication
2 Dualism
 2.1 Persons and immaterial stuff
 2.2 Arguments from the unity of consciousness
3 Arguments against dualism
 3.1 Illegitimate extensions of the concept of personal identity
 3.2 Verificationism
 3.3 How do I know who you are?

1 The problem of duplication

Swinburne begins by giving clear expositions of what he takes to be the two main alternatives to his view: psychological theories (which he calls ‘memory and character’ theories) and bodily theories (the main version of which he discusses he calls the ‘brain theory’). His principal argument against these views is a problem we have encountered before: both of these views seem to allow the possibility of duplication, in the sense that, whatever relation they claim to be sufficient for personal identity, we can construct a case in which you bear that relation to two future people. But since these people are two and not one, they are not identical to each other; so they can’t be identical to you; and the relation which was claimed to be sufficient for personal identity turns out not to be.

Examples: Guy Fawkes, and cases of brain hemisphere transplant:

“Brain operations which remove substantial portions of the brain are not infrequent. It might be possible one day to remove a whole hemisphere, without killing the person. There are no logical difficulties in supposing that we could transplant one of [the person’s] hemispheres into one skull from which a brain had been removed, and the other hemisphere into another such skull, and that both transplants should take ...” (14-15)

We can always add clauses to our theory which can block the possibility of duplication; but these are to be rejected for the same reasons suggested by Parfit.

As Swinburne sees it, these duplication examples give us only two choices:

The first of these views is similar to the view that we found in Parfit. Swinburne does not think that this view is plausible. He defends the latter view, which he calls ‘the simple view.’ In the second chapter, he shows how the simple view leads to a kind of Cartesian dualism.

2 Dualism

2.1 Persons and immaterial stuff

The principal arguments Swinburne gives for dualism are already to some extent familiar. He argues, first, that we can imagine someone acquiring a new body, or even existing in a disembodied state (23-4). But, if either of these things really are possible, this means that persons ⁄= their bodies. Second, we are familiar with cases of amnesia, in which people continue to exist despite losing most or all of their memories; and we can make sense of stories in which people continue to exist after death, but without any memories of their time on earth. But, if this really is possible, this means that persons ⁄= their memories and psychologies.

This gets us the negative result that personal identity is not analyzable in terms of bodily or psychological continuity. We get from there to dualism via what Swinburne calls ‘the Aristotelian understanding of the criteria for the identity of substances.’ The Aristotelian criterion is basically this:

For some kind of thing — e.g., a dog, a fern, a table — to continue to exist is for the stuff out of which it is made to continue to exist (permitting gradual replacement of parts), and for it to maintain the form characteristic of that kind.

Swinburne thinks that this is a plausible view, and so he thinks that it is plausible that some view like this should apply to the identities of persons. But the foregoing ‘duplication’ argument shows that if it does apply to persons, ‘the stuff out of which persons are made’ cannot be, e.g., the matter which makes up one’s brain; and analogous argument shows that it cannot be the matter making up any part of a person’s body. So, says Swinburne,

“We may say that there is stuff of another kind, immaterial stuff, and that persons are made of both normal bodily matter and of this immaterial stuff but that it is the continuity of the latter which provides that continuity of stuff which is necessary for the identity of the person over time.” (27)

How this view can make sense of the idea that my left leg is a part of me; the distinction between essential and accidental parts of a thing.

2.2 Arguments from the unity of consciousness

Imagine (p. 43) watching a train:

“the observer on the bank has the following experiences: S sees train T at place p followed by T at place q; S sees T at q followed by T at r; S sees T at r followed by T at u, and so on. But then that is not quite a full description of his experience. For if those were all the data of experience, S would need to infer that the second experience which I have described succeeded the first (rather than being one which occurred on an entirely different occasion). Why he does not need to infer this is because it is itself also a datum of experience ...And what the subject of experience is aware of is of those experiences as his, that is as having a common subject.”

See also Swinburne’s discussion of simultaneous experiences of different sense modalities (45-48)

A question about this argument: suppose that Swinburne is right, and that we do have a kind of awareness of ourselves as things which persist over time, and that this awareness underwrites all of our knowledge of change. Why does this count in favor of dualism? What other views of personal identity might it rule out, if any?

3 Arguments against dualism

3.1 Illegitimate extensions of the concept of personal identity

The first argument against dualism begins by noting that the concept of a person was designed for use in ordinary situations, in which both physical and psychological continuity is preserved. But arguments for dualism always make use of some relatively far out scenario, such as cases of teletransportation or brain splitting. But why should we think that the concept of a person is sufficiently well-defined to even cover cases like this? When confronted with a case like teletransportation, we should just say something like: once you have described all of the facts about what material goes where, and what the psychologies of the relevant creatures are like, there’s nothing else to be said. The concept of a person will not tell you which of the results of the teletransportation really is the original person.

Two analogies: absolute up and down, and the time on the sun.

Swinburne’s reply: lots of concepts were created for one use, but have application in very dissimilar cases. One interesting example he gives is cause and effect.

Do you think that ‘person’ is more like ‘up’ or like ‘cause’?

3.2 Verificationism

A second, and related argument against dualism also focuses on alleged problems with the examples used to argue for it. The view known as verificationism says (in one of its forms) that a sentence can only be true or false if it can be verified by experience. But, for example, which person is identical to the original person in brain transplant or teletransportation cases cannot be verified. So, it is neither true nor false that the original person is identical to one of the people after the teletransportation/brain transplant.

One reply to this argument is that it leads to implausible results. For example, it leads to the result that this sentence is neither true nor false:

All ravens are black.

Can you see why?

One might reply that this sentence is not conclusively verifiable, but it is conclusively falsifiable. And the claims that dualists make about these cases are not conclusively falsifiable either; so perhaps the verificationist critic of dualism should say that only claims which are conclusively falsifiable can be true or false.

This also leads to implausible results. For example, it leads to the result that this sentence is neither true nor false:

At least one raven is white.

This sentence, while it may be conclusively verifiable, is not conclusively falsifiable — but it still seems to be true or false. This suggests a third option: maybe a sentence can only be true or false if it is either conclusively verifiable, or conclusively falsifiable.

Can you think of any sentences which seem to be either true or false, but which are neither verifiable nor falsifiable? How about:

For every action, there is an equal and opposite reaction.

Is this sentence verifiable? Is it falsifiable?

One might weaken verificationism further, and say that a sentence can be true or false only if there can be some evidence which can count for it or count against it. This leads us to the next objection against dualism, which Swinburne discusses in Chapter 4.

3.3 How do I know who you are?

It seems clear that we all the time unproblematically re-identify persons as the same as individuals we have come across in the past. When I walk into class to give a lecture, you unproblematically identify me as the same person who gave the last lecture, and the one before that. But to many people this fact has seemed to pose a problem for the dualist theory. After all, according to the dualist, the fact that I am the same person as gave the last lecture is constituted by the fact that the same immaterial soul is a part of this person as was a part of the person who gave the last lecture. But you can’t see immaterial souls. So, if sameness of persons really is just sameness of immaterial souls, how can we so much as use vision to re-identify people? This is the challenge that Swinburne takes up in the last part of the reading.

This challenge is often pressed by proponents of bodily and psychological theories of identity. After all, they might say, we usually re-identify people by their bodies (or psychologies/character traits). This is totally unmysterious if personal identity just is identity of body (or psychology/character traits). So this seems to be a point in favor of bodily and psychological theories. On these theories, our evidence for personal identity would, at the least, be more direct than it is on the dualist view.

(One minor point that Swinburne mentions (p. 49) is that this is overstated a bit. We identify people typically by things like their outward appearance and the sound of their voice. But no one explains personal identity in terms of outward appearance and sameness of voice; rather, the relevant theorists explain personal identity in terms of memory and sameness of brain. But outward appearance is at best indirect evidence of these things.)

Swinburne’s response to this challenge has two steps:

  1. Our apparent memories of the past can, even on the dualist view, give us evidence of our identity over time.
  2. Every other source of evidence we use for personal identity (whether of ourselves or others) depends ultimately on our apparent memories.

First, why does Swinburne think that the other sources of evidence we use for personal identity depend ultimately on apparent memory? The story goes something like this. First, imagine that a certain kind of ‘body swapping’ was a regular feature of our lives:

“Suppose that a person in body B1 on even days apparently remembered (almost) everything done and experiences by the person in that body on even days, and (almost) everything done and experiences by the person in another body B2 on odd days, but nothing done and experienced by the person in B1 on odd days nor anything done and experienced by the person in B2 on even days. ...Suppose too that character goes with apparent memory. ...

If this kind of apparent body-swap was a normal, regular, exceptionless feature of life, it seems patently obvious that we would not claim that bodily continuity [was good evidence for] personal identity. ...” (52-3)

This kind of story seems to indicate that we rely on outward appearance and bodily continuity in making judgements of personal identity only because we have found these to be correlated with sameness of memory and character — because, if we imagine this correlation broken, we find that we don’t trust sameness of outward appearance any more.

Suppose that this is right. This seems to help the proponent of the psychological theory more than the dualist. After all, this just explains how I know about the identities of other people on the assumption that they know that they are the same person over time. On the psychological theory, which explains personal identity in terms of apparent memory, this assumption does not seem like a problem. But this is not so for the dualist. After all, none of this helps to explain why my apparent memories justify me in believing that the same immaterial soul has been attached to my body for the duration of my life. How, on the dualist theory, can I even know that I am the same person over time?

Swinburne’s answer to this question relies on his ‘principle of credulity’ for memory and perception. How does this answer go? Is it plausible?