Descartes’s dualism became the basis on which many have reconciled their religious beliefs with their acceptance of modern mechanistic science. The nature of a mind, he claimed, is very different from that of a material body (any piece of matter) for the following reason:
“We cannot understand a body except as being divisible, while by contrast we cannot understand a mind except as being indivisible. For we cannot conceive of half a mind, while we can always conceive of half of a body, however small.”
What he seems to have intended is that the destructibility of material bodies follows from the fact that they are inherently divisible: whereas minds, being indivisible, are not destructible for this reason .
The Platonic argument from the simplicity of the soul
Plato wrote in Phaedo of Socrates’s argument: anything that is incomposite or simple is immune to being dispersed in this way since it does not have parts. The soul is an ‘incomposite’ or simple thing. Therefore, when the body is dispersed after death, the soul will live on. For souls are not liable to be dispersed. Plato’s argument appears to be that destroying something is always a matter of breaking it into parts.
Anything that cannot be dispersed is immortal.
Anything that does not have parts cannot be dispersed.
The soul does not have parts.
The soul cannot be dispersed. (Sub-conclusion from Premises 2 and 3)
The soul is immortal. (Conclusion, from Premise 1 and Conclusion 1).
The assumption is that being broken into parts is the only way things naturally get destroyed. R.G. Swinburne objects that a table reduced to liquefied form is no longer a table because it has lost the properties that are essential to its being a table. There might be ways for the soul to go out of existence which are quite natural to it and quite different from the ways in which material things go out of existence.
The soul as an illusory entity
The soul is not, according to Kant, a thing at all. Phrases like ‘my soul’ and ‘my mind’ do not refer to a special entity which can be thought of as existing apart from other entities. For example, that the mind can seem an entity analogous to a safe is an illusion of language encouraged by phrases like ‘I will keep it in my mind’. Gilbert Ryle’s approach (‘The Ghost in the Machine’) assumes that the roots of the temptation to believe that minds are substances lie in language.
The soul as an unwarranted assumption - Entities should not be multiplied beyond necessity is known as Occam’s Razor.
The onus lies on those who claim there are extra kinds of entity in the world to prove their case. The rest of us are entitled to presume these extra entities do not exist until it has been shown that they do. The point is not that none of these entities exists, still less that we know they do not. The point is rather that we are entitled to presume that they do not until those who claim they do give us positive reasons for supposing they do.
Descartes certainly thought he was entitled to infer that he was a thinking thing. If we apply his method of doubt strictly, all he was entitled to infer from the existence of his doubts was that doubting went on and not that he was a substantial mind.
Cartesian dualism and immortality
“And so, my soul, you have been a captive for a long time. This is the hour at which you must go out of prison and leave the encumbrance of this body behind you.”
Dualism helped to make immortality credible in a way it would not otherwise be.
The animals dilemma
Descartes thought that animals were just like machines, or ‘automata’, operating like elaborate clockwork without any consciousness.
In the first case, animals are too much like humans, being naturally immortal; this is contrary to orthodox Christianity. In the second case, animals are not sufficiently like humans, being mere machines; this is contrary to common sense.
If animals, like humans, have souls, then these souls are also indivisible and hence are also naturally immortal.
If animals do not have souls, then they are mere machines and do not feel pain.
Descartes grasped the second horn.
Problems of personal identity
To be capable of immortality a creature needs more than consciousness or feeling. Immortality appears to require personal identity, i.e. the conscious continuation of the same person from this life on to the next.
Immortality and personal identity
What kind of immortality do we want?
We would need to be able to identify our loved ones and they us, and all of us be able to recollect our pasts and our associations with one another.
Christian, Jewish and Muslim theologians will all insist that an individual must remain the same person in the afterlife because all individuals are liable to be rewarded or punished in the afterlife depending on how they conducted themselves in this life.
Reward and punishment in the afterlife makes no sense if souls lose their individuality and continuing identity.
“Such immortality without memory is altogether useless for morality, for it upsets all reward and punishment.” – Leibniz
Not any life after death is one we would want. Some people’s Heaven might well be other people’s Hell. A traditional picture of Heaven, which offers the prospect of an eternity of choral singing, may delight some and fill others with a sense of boredom.
A dualist account of personal identity
“That which the consciousness of this present thinking thing can join [sc. ‘to’] it self, makes the same Person, and is one self with it, and with nothing else; and so attributes to it self, and owns all the Actions of that thing, as its own, as far as that consciousness reaches, and no farther; as every one who reflects will perceive.” – John Locke
Locke is talking about personal memory or recollection. Memory is a necessary and sufficient condition of personal identity.
Memory as a necessary condition of personal identity
Thomas Reid produces the example of a General who cannot remember his childhood, but who can remember a time when he could remember his childhood.
“Whence it follows, if there be any truth in logic, that the general is the same person with him who was flogged at school. But the general’s consciousness does not reach so far back as his flogging; therefore...he is not the person who was flogged. Therefore the general is, and at the same time is not, the same person with him who was flogged at school.”
Locke might have responded to Reid by referring to a distinction between the conditions under which someone can be said to be the same man and the conditions under which they can be said to be the same person. Memory is not necessary for someone to be the same man and that, Locke might have replied, is all the counter-example shows. Reid might reply that the distinction does not help since the general is not only the same man but, we would all agree, also the same person.
Memory as a sufficient condition of personal identity
It is true by definition that I can only remember doing the things I have actually done. But our memories let us down not only because we cannot always recall things we actually did but because we are prone to believe that we have done things we never did.
Idealism and immortality
George Berkeley suggested an amendment to Malebranche’s occasionalism, allowing that all spirits – including humans – were in their nature ‘active’ and that they should all be admitted as true causes, as well as God. But other causes we observe in nature are not true causes but only ‘occasions’. For Berkeley, this cause must be a spirit and, he suggests, the ideas we have when we see tables, sunsets and so on are all produced in us directly by God.
Thus Berkeley was led into idealism, claiming that everything was a spirit or an idea – a mental content of a spirit. Berkeley’s point is that there is no good reason to suppose the existence of what philosophers have called ‘material substances’.
Berkeley’s argument for immortality
“...they who assert the natural immortality of the soul are of opinion, that it is absolutely incapable of annihilation even by the infinite power of the Creator who first gave it being: but only that it is not liable to be broken or dissolved by the ordinary Laws of Nature or motion.”
“We have shown that the soul is indivisible, incorporeal, unextended, and that it is consequently incorruptible. Nothing can be plainer, than that the motions, changes, decays, and dissolutions which we hourly see befall natural bodies (and which is what we mean by the course of Nature) cannot possibly affect an active, simple, uncompounded substance: such a being therefore is indissoluble by the force of Nature, that is to say, the soul of man is naturally immortal.”
The argument appears to be that only extended, compound things are liable to be dissolved or corrupted. This is so of corporeal things. Souls, however, are simple and uncompounded and so not liable to be dissolved or corrupted, at least by natural means. The objections that have been raised to the Platonic argument from the simplicity of the soul also apply to Berkeley’s argument.
Berkeley’s argument for immortality brings out how, in some respects, idealistic monism need not be different from radical dualism.
Berkeley and the animals dilemma
It looks as if Berkeley ought to say animals are immortal, if spirits are characterized by being able to perceive and to act. His inclination seems to have been to say that animals were an inferior sort of spirit and to reject the Cartesian view that they were mere machines. . If animals are naturally immortal then it is not clear why they do not have an equal status in God’s eyes with human beings. It is difficult to imagine the good Bishop Berkeley being willing to think such thoughts.
The transmigration of souls
The transmigration of souls clearly involves a dualist view of the relation between soul and body. The same soul pursues its career (wanderings), on this account, by being joined to a succession of different bodies . There is a simple empirical difficulty, namely, that the number of living things (in the Pythagorean version) and the number of humans (in Luria’s Kabbala) will need to remain constant or at least – since new souls might be created – not decline. But a number of disasters have reduced human populations by millions.
“Metempsychosis [i.e. transmigration of souls] would be against the rule that nothing takes place by leaps. The transition of the soul from one body to another, would be the same as the leap of a body from one place to another, without traversing the intermediate space.” – Leibniz
His point, as he makes clear elsewhere, is that all change in nature happens gradually and not all at once. It is sometimes called ‘the principle of continuity’, since the claim is that all natural processes are continuous. It is this principle which, Leibniz holds, is violated by the theory of transmigration.