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There has been a lot of talk recently about various aspects of artificial life - artificial intelligence, sentient machines, computers gaining self-awareness, and so on.
It seems self-evident that we can easily distinguish between living and non-living matter. What I would like to argue here is that it is also easy to distinguish between real life and virtual life. So – let's start with describing real life.
We can’t say exactly what ‘life’ is, because life is an abstraction – but we can describe what a living organism is, because that is a real thing (many real things) which can be observed. So let's start with a fairly obvious statement.
A boundaried physical system which is capable of reproducing in the right environment is a living organism.
(This is elaborated in 'More Precisely' below.)
It is a physical system. Let’s not get confused at this stage with questions about the possibility of virtual life and sentient AIs: every living organism we have encountered to date has been physical in nature.
It is a boundaried physical system. Without a clear boundary, we can neither recognize an organism nor tell when it has reproduced.
It can reproduce. Reproduction is the most fundamental characteristic of life; all the other commonly identified characteristics of life only matter because they are needed in order for the organism to reproduce.
It must survive. The organism must survive for as long as is required in order to reproduce: this differs from one organism to another. Some organisms (like salmon and octupi) die after reproducing, while other organisms (like humans) need to care for their children - or even their grandchildren - to ensure their success.
Sex and survival are the two basic activities of all living organisms.
Every living organism hs certain attributes: it feeds, it has feelings, it has desires, and it has purpose. How does a complex computer or AI compare?
It feeds. Food is not just a source of energy: the organism takes part of the environment, and turns this food into itself. A computer can be said to 'feed' upon the electricity supplied to it, but this electricity does not become transformed into the electrical components it is made of. And every living organism has specific food needs: a Koala will eat Eucalyptus leaves, not Sycamore leaves. Feeding and processing the food takes much of the activity of a living organism consists of feeding and processing the food, then using it to grow and replace cells. No mechanical or virtual device engages in anything at all comparable.
It has feelings. The organism feels its environment - that is, the environment changes it in ways it can detect; it also feels its internal state, and these are not entirely distinct activities. Feeling the temperature or tasting the food is quite different from a data feed providing a number which represents the temperature, or a chemical analysis indicating the constituents of the food. Some feelings are neutral, but many feelings are good (ones which are desired) or bad (ones which are avoided). The organism feels good when it feeds, and feels hunger if it does not feed; it also sometimes feels pleasure and pain - if not as we understand them, then at least to the extent possible for its level of development.
It has desires. The organism wants to have the good feelings and it wants to avoid the bad feelings. These desires are inherent, not imposed; they are built into the fabric of its being. A machine cannot want to survive: it can only act in a way to preserve its integrity if it is instructed to do so.
It has purpose. Every living organism has two basic built-in purposes: sex and survival - it aims to reproduce, and to survive until it has reproduced. And it acts with purpose, which is not only about sex and survival directly, but also about satisfying its desires. Again, these are all innate, buit-in to every cell of every living organism. In comparison, a machine, computer or AI can only seek to do what it is instructed to do: it may be said to have a purpose, but that purpose is given to it - the purpose does not arise from within.
All of this discussion is about the things which characterize real life, as opposed to artificial or virtual life. It does not attempt to describe everything which living organisms are capable of. At one point, Jesus talks about 'life in all its fullness', which we can reasonably assume encompasses much more than just feeding well, finding pleasure and avoiding pain. In fact, His teaching and example shows that it is possible to transcend these concerns - perhaps not completely, and not all the time, but they do not have to control our lives. However, such considerations are not part of this article.
A boundaried physical system which is capable of reproducing in the right environment is a living organism. Other similar boundaried physical systems are also living organisms, despite being sterile. There are four basic reasons why a living organism may be sterile:
- it may be damaged in some way;
- it may suffer from genetic errors;
- it may have been produced by an attempt at reproduction between living organisms which cannot produce fertile living organisms; or
- it may help other living organisms to reproduce.
The standard 'difficult question' here is whether viruses are alive. The question is unimportant: you can define 'alive' in whatever way is most convenient. They are not living organisms in the sense I describe above; on the other hand, they clearly belong to the 'living matter' category - in a universe without life, viruses could not exist.