An interesting example of the different ways that scientists and ‘pure’ philosophers view things arose in an exchange I had in the comments of a previous post.

Commenter Kenneth brought up an interesting argument that I had not heard before for the existence of the afterlife, an argument that he said had originally been proposed by the philosopher Spinoza (1632-1677). Basically the argument boiled down to the assumption that each one of us is simply a collection of atoms arranged in a particular way. When a person (A) dies, those atoms are dispersed and join the universe of atoms that percolate through space and time. But there is always the possibility that, purely by chance as a result of random motion, a set of atoms will arrange themselves in exactly the same arrangement that made up A when A was still alive. So thus A will have been ‘reborn.’ Kenneth argues that thus the existence of life after death has been established, at least in principle.

The nature of the argument can be perhaps understood better with a simpler example of thoroughly mixing ink and water in a glass and then leaving it alone to sit undisturbed. We would think that this mixing is an irreversible process and that separation into water and ink again would not be possible except as a result of extraordinary efforts by external agents. But in fact if you simply wait long enough, there is a very remote possibility that the random motion of the individual ink and water molecules will result in a momentary spontaneous separation of the mixture in the container into two separate regions, one of pure water and the other of purely ink molecules (whatever ink molecules are).

Since all that this argument requires is the ability to wait for a very long time for which these unlikely events to occur, Kenneth has satisfied himself, from a philosophical point of view, that Spinoza’s argument is valid. And that once we concede the possibility that someone’s atoms can be reconstituted in its original form, the existence of life after death has been established, at least in principle

But science does not limit itself to these ‘in principle’ arguments. Such arguments are just the first steps. Science is always looking at the detailed consequences of such ideas in order to translate them into research programs. And this is where Spinoza’s argument for the possibility of an afterlife breaks down.

For one thing, the human body is not just an arrangement of atoms, like that of molecules in a mixture of ink and water, or the oxygen and nitrogen molecules in a container of air. The atoms in the human body are bound together in complex organic molecules, which are in turn held together by other forces to form cells and tissues and so on. It is not enough to just bring the atoms together, you also have to create the chemical reactions that fuse them into these molecules, and this requires energy from the outside used in a very directed way.

It is like frying an egg in a pan. Just breaking an egg into a skillet and leaving it there will not result in a fried egg, however long you wait, unless there is a source of energy to drive the reaction forward. A fried egg is not just a rearrangement of the atoms in a raw egg. It is one in which new compounds have been created and the creation of these compounds is a non-random process.

In addition, the probability of all the atoms that make up your body randomly arriving at the same locations that they occupied when you were alive is microscopically small. This is not a source of concern to Kenneth because all he needs is that this probability not be zero in order to satisfy his ‘in principle’ condition. But there is an inverse relationship between the probability of an event and the likely time that you would have to wait for the event to occur. For example, if you repeatedly throw a die, you would have to wait longer to get a six than to get just any even number because the probability of the former is less than that of the latter.

In the case of the body’s atoms coming together again, the probability is so small that the expected time for it to occur would be incredibly long. Again, it would not matter if this were a philosopher’s ‘in principle’ argument. But those arguments tacitly assume that nothing else is changing in the environment and that we have an infinite amount of time in the world to wait for things to occur.

But in reality events are never in isolation and science is always concerned about the interconnectedness of things. And this is where the ‘in principle’ argument breaks down. We know that the lifetime of the Sun is about ten billion years and that it will then become a huge ‘red giant’ that will grow enormously and even envelop the Earth. And later still, all the energy producing nuclear reactions in the stars will end, resulting in the heat death of the universe. So there will not be any surplus energy around, even in principle, to drive the chemical reactions to reconstitute the body’s molecules, even if they did manage to arrive randomly in exactly the right positions.

I think that this is where scientific research and philosophical speculations diverge. A scientist is not interested in just ‘in principle’ arguments for the afterlife of the kind that Kenneth says Spinoza makes. To be become interesting to scientists, Kenneth will have to provide at least numerical estimates of the probability the body’s atoms reconstituting themselves, and then use that probability to estimate the expected time for such an event to occur.

If that time is more than the expected heat death of the universe, then the question becomes moot. If it is less, then the scientist will ask if there is enough free energy at that time to drive the reaction forward and what is the probability that this energy will spontaneously be directed at the atoms in just the right amounts and directions to recreate the human body.

All these considerations, when brought together, suggest that Spinoza’s argument fails and that life after death as proposed by him is not going to ever happen.

That is the kind of difference between the approaches of pure philosophy and science.