July 15, 2019, by Brigitte Nerlich

When is a metaphor not a metaphor?

A few weeks ago Daniel Nicholson posted an article on twitter entitled “Are cells really machines?” This made me think, and I wrote a blog post pondering the relations between science, metaphors and technology.

In this post I want to reflect on another aspect of the relation between science and metaphors, namely on when metaphors are not really metaphors…. These are only some random thoughts though. I’d love people to chip in with their own.

Nicholson made the point that cells are not ‘really’ machines, but are much more fluid, flexible and dynamic, and, most importantly, self-organising and self-sustaining, as well as adaptive. Machines, as we know them, are not like that, and cells, as we know them, are not really like the machines we know. But may there be machines in the future that are more like cells and will cells then really be more like machines? That’s something to think about.

A related question is: Are cells really really not machines, even if we only think of them in terms of machines of the present not the future. As one twitter person said: “I think cells _are_ machines, but biologists have been abusing the term to mean something it doesn’t (and possibly to conceal the fact)…”… but he did not elaborate on this intriguing thought. We have to have a chat sometimes.

So lets take some examples and ask: When is a metaphor not a metaphor?

The heart is a pump.
The brain is a computer.
The eye is a camera.
The universe is a clockwork.
DNA is a code.
Genes are blueprints.

All of these metaphors could, of course, only have been produced once the technologies were in place that could be used as ‘source domains’ to map resemblances or likenesses onto target domains (hearts, eyes, DNA). As another twitter person said: “Interesting how the names for mechanisms in science are influenced so much by contemporary life. Yeast mating locus switching was worked out in the 1980s and uses terms like ‘cassette and playback’. Walkman-era science.” ‘Mechanisms’…. I just leave that there. (Oh my, I have just seen that Nicholson has written about three meanings of mechanism in biology…) Back to my examples.

The heart is a pump

As I am on holiday, I turned to my instant focus group. I asked my husband: “Do you think the heart is pump?” And he said (I think), “Yes it is. It’s primary function is to force fluids along tubes under pressure; it has one way valves to stop it going the wrong way; it operates by cyclically admitting fluid through one aperture and expelling it under pressure through another (in fact it’s two pumps operating in parallel).” He ended by saying: “I can’t think of a more prototypical description of a pump.”

Then I asked my son and he said: “Hmmm, it sort of is a pump, but a very particular one. It’s not a hand-pump, for example.”

So, should we say: The heart is not really a pump. Or should we say: The heart really is a pump. What do you think?

The brain is a computer

The brain is a computer…. Here again, some people will probably argue that it really is a computer, as both brain and computer are information processing machines (which also means that brains are machines), while others might say it fits certain aspects of universal Turing machines but not others. This could be a long discussion!

The eye is a camera

Now, that’s interesting. I think everybody would agree that in some respects the eye is like a camera, but that it really is not a camera…. Despite this, this metaphor has a heuristic function. For example, in the 19^th century, Herman von Helmholtz used “The eye as an optical instrument” as the title for one of his Popular Lectures! This heuristic function can also bring about surprising results. As somebody wrote in a blog post: “Basically in doing all this research about how the human eye is like a camera, what I really learned is how human vision is not like a photograph.” It’s interesting to see that this person used a simile (like) not a metaphor.

The universe is a clockwork

As Wikipedia points out: “In the history of science, the clockwork universe compares the universe to a mechanical clock. It continues ticking along, as a perfect machine, with its gears governed by the laws of physics, making every aspect of the machine predictable.” (Which also means that the universe is a machine) (And, according to Schrödinger and Monod, for example, life too is a clockwork… and a thus a machine…… another long story….)

This metaphor has had huge heuristic value, and still has, just like the machine metaphor in biology, despite the fact that clocks now are largely digital, as are machines. Visions of the universe beyond classical mechanics have not yet been captured by metaphors that are that compelling. Or have they?

DNA is a code

What about DNA as a code? Some would say, like my husband said of the heart, of course it is. Even Nicholson writes in a brilliant 2018 book chapter on life as flow that: “Ultimately Schrödinger was right to suppose that genes are material carriers of information. There really is a code connecting DNA to RNA to the primary structure of proteins” (2018: 160). Others would perhaps ask, like my son did for the heart, what sort of code are we talking about: the Morse code (which inspired Schrödinger) or some other code, a substitution cypher for example. (I should say that when I asked him whether DNA was a code, he said yes immediately, but that it ‘really’ was a family of codes; whereas my husband said that, strictly speaking, to him, it’s a map).

[Found a day after writing this post: An article by Ulrich E. Stegmann, entitled: “‘Genetic Coding’ Reconsidered: An Analysis of Actual Usage” – well worth reading!]

Genes are blueprints

Some people would say quite emphatically that genes are not blueprints. However, other people use that metaphor emphatically in book titles, despite the fact that they perhaps shouldn’t…. Many would probably argue, like this article in the Huffington Post, that “’Blueprints’ is a poor way to describe genes.” Even ordinary people find that metaphor ‘outdated’. What do you think? Has this metaphor lost its original heuristic function? Is it as defunct as blueprints are in architecture? (For a longer discussion of the blueprint metaphor, see my old post here)

Similarity and similes

All this seeing and understanding something in terms of something else depends on discovering or recognising resemblances and similarities, on pattern recognition. Now, the question is: Would all our heartache and indeed headache about when something is a metaphor or not disappear if we just used similes (more visible comparisons, using words like ‘like’) instead of metaphors?

The heart is like a pump. The universe is like a clockwork. The brain is like a computer. The eye is like a camera. In some instances, like the eye, this works, but in others not, as some people would still insist that hearts are not just like pumps but ARE pumps and that cells really ARE machines – but then the things talked about are no longer talked about metaphorically. The metaphor disappears in a puff of smoke.

Some things to think about – a random list

We should think about the heuristic function of metaphors. So when I say the brain is a computer, I can ask all sorts of questions, come up with all sorts of hypotheses about how the brain functions. This is not the case when I say, metaphorically, that the brain is a sieve or the brain is a sponge.

We should think about networks of metaphors spun around one source domain. The machine as source domain has a lot to answer for in science and has spun out a network of targets that have created science as we know it. What does this mean for science and public understanding of science.

What does it mean to say that A is B? (There will be philosophers out there who have thought about this, I am sure)

Is there a difference between the use and usefulness of metaphors and similes in science?

And what does ‘really’ ‘really’ mean?

Happy holidays!

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