It would be easy to talk of the squirrel as if it had human thoughts: planning ahead, wanting to have enough to eat when leaner times come, or collect as many nuts as possible before other animals get hold of them. Even scientists sometimes use intentional language for living things in their published work. They might seem to give animals a personality, as if “every creature acts in its own interests”. Even in cells or tissues, things are often described as if they have a goal in life – such as the function of DNA rearrangements, or the purpose of a protein.
Some scientists say that this purposeful language is just metaphorical, no doubt based on the assumption that humans are the only living things that can have intentionality. I remember being gently told off as a student for using these sorts of words for the things I was working on, and was reminded that we can only speak of mechanisms in science – not meaning. But is that caution always necessary? Is there no room at all for purpose in biology? This was the subject of Philosopher Samir Okasha’s lecture at a conference last year on “Biological, philosophical and social science perspectives” in evolutionary biology, and I will do my best to summarise his main points here.
Okasha has wondered whether the language of intention could be more than just a metaphor in biology. Psychologists have known for a while that we have a natural tendency to assume objects or events have a mind of their own. So children might say the sun shines because it wants to make us warm, or that rocks are pointy so people won’t sit on them. You might think scientists are doing a similar thing when they speak of organisms – or parts of organisms – having goals, but they are actually doing something different. No one would write in a scientific paper that a plant is trying to be tall so people can enjoy looking at it, or that the deer has long legs so it can provide more venison for restaurants. These researchers are speaking of real attributes: a plant is growing towards the sun, or a deer is running for its lifeSo could organisms other than ourselves have interests, strategies, or goals? Okasha believes that a biological thing – whether an organism, a group of organisms, or even a gene – can act with a certain kind of intent. It might be optimised for a certain situation, it may adapt its behaviour or be flexible to different circumstances, or it may even work towards a specific end. Of course a Scrub Jay storing away food is more intentional than a gene responding to circumstances, but surely we can say in a limited way that an organism wants to do something. Rather than just speaking of a single mechanism, and what that one activity is achieving, we can talk about the whole organism and its goals or preferences. A single trait – such as a swallow’s migration or an insect’s mating display – has a specific function, but the organism as a whole is working towards something.
Human beings tend to have overall aims, and the various things they do tend to be line with them. In multiple personality disorder, a person’s goals break down and become conflicting. Something similar can happen in other animals, with one trait working against another in an uneasy truce. For example some fruit fly males can’t have male offspring – which means that one of their chromosomes (the y chromosome) loses out, while the genes on the other sex chromosome (the x chromosome) win. But on the whole, organisms tend to have an overall purpose, which is to survive and thrive – producing offspring.
Okasha thinks that there may be a case for using intentional language in biology, but it needs to be done with care. An organism may look as if it’s behaving rationally, but it may just be ‘proto-rational’ – and not actually planning and making decisions. The language of purpose may be valid in a limited sense, but he’s not suggesting that scientists borrow ideas from Beatrix Potter in their own publications.
So the squirrel outside my window may not fully understand what it is doing or why, but according to Okasha I don’t have to use completely impersonal language to describe its activities. To avoid the language of purpose entirely would be to deny the nature of the squirrel.
For those outside of science, this conversation might seem like a storm in a teacup, but it is a significant debate in evolutionary biology. I know that others will disagree with Okasha, but it’s interesting to hear at least one reputable philosopher who is moving way from the outright rejection of purpose in biology. I am not suggesting that we should inject theological or metaphysical meaning into science. But perhaps this ever so slight relaxing of language is a sign of openness to a discussion of the larger questions that science raises (such as the value we ascribe to these processes), but which it cannot answer by itself.
You can listen to the whole of Samir Okasha’s lecture here.
Samir Okasha, Philosophy of Science: A Very Short Introduction (Oxford University Press, 2002).
 Ernst Meyer, Toward a New Philosophy of Biology, (Harvard 1988), page 30.
 James Watson et. al., Molecular Biology of the Gene, 6th Edition, (CSHL Press, 2008), page 369.
 Jeff Hardin et al, Becker’s World of the Cell, 8th Edition, (Benjamin Cummings, 2012), page 50.