November 18, 2022, by Brigitte Nerlich

Scientists do metaphor

I was idly browsing my Twitter timeline recently (probably for the last time), when my eyes fell on some tweets by Buzz Baum, a cell biologist, saying that he had spoken about metaphor on a BBC radio programme (oh, I thought!) which unfortunately had now been deleted from BBC Sounds (oh no, I thought). He summarised the gist of the programme thus: “We talked about the joy of being a scientist and finding yourself in a new landscape where all your metaphors fail you.” (oh wow, I thought).

These revelations emerged as part of a conversation between Buzz and Kevin Mitchell, a neurogeneticist, about something that, like so many science things, went somewhat over my head. Anyway, Baum said: “My final thought on the subject: Hsp90 isn’t a capacitor. It’s a chaperone. That’s the problem.” I know what a chaperone is but that’s about it. The rest was darkness.

Interestingly, Robert Insall, a computational cell biologist asked: “You mean a little old lady who sits all night with your daughter to make sure she can’t get a shag? (almost every word in modern biology is an abused loan with concealed meaning…)”, which set off discussions about the fact that biology is a web of gradually failing metaphors – with contributions by Philipp Ball, a science writer and Jennifer Rohn, a cell biologist and novelist, and a reference to Andrew Reynold’s book Understanding Metaphors in the Life Sciences.

Scientists talk about metaphor

That made me think. I have written in the past about what one may call big metaphors that non-experts can vaguely understand, such as DNA, genomes or genes as maps, books, recipes and so on. But I had never really looked into the practical details of how scientists actually negotiate metaphors in their daily scientific lives (with one slight exception where I looked at how they talk about gene editing.). How could I find out? I rummaged around a bit on the internet and found a little gold mine.

I stumbled upon a commentary by Derek Lowe, an organic chemist, entitled “Block that metaphor” published in Science, in which he mused about when metaphors are useful and when they are harmful. The comments underneath the post were intriguing. I have sorted them here into thematic groups dealing with various aspects of metaphors in science, including the breakdown or failure of metaphors. Let’s start with a bit of philosophy.

Pictures, ladders and a bit of Wittgenstein

One of the first comments I read was this, and I have to say, like so many things, the science went over my head:

“A couple of years ago (2nd or 3rd year undergrad) I had this harmful (or misleading, to be more exact) mental construct for Knoevenagel condensation. I pictured it as the carbonyl being brutally rammed, oxygen first, into the activated methylene group, producing water molecule instantly from the sheer force of the impact. All the while I knew that this was not how the reaction proceeds, but I simply couldn’t help having this mental image.”

Basically, I think the commenter was furious that the wrong image (conceptual source domain) had kept him captive and hindered his exploration of the target domain (Knoevenagel condensation – according to wikipedia “In organic chemistry, the Knoevenagel condensation reaction is a type of chemical reaction named after German chemist Emil Knoevenagel” and there is more).

This reminded me of what Ludwig Wittgenstein had said in his Philosophical Investigations, that is, his investigations into language, thought and action: “A picture held us captive. And we could not get outside it, for it lay in our language and language seemed to repeat it to us inexorably.“ (Paragraph 115)

Though the above commenter did not mention Wittgenstein, another one did, this time referring to his earlier work, the Tractatus Logico-Philosophicus which explores the relations between language and reality: “One can extend that thought to all sensory perception as well. A nice metaphor from Wittgenstein’s Tractatus relates: ‘6.54 My propositions are elucidatory in this way: he who understands me finally recognizes them as senseless, when he has climbed out through them, on them, over them. (He must so to speak throw away the ladder, after he has climbed up on it.) He must surmount these propositions; then he sees the world rightly.’”

Strangely, that is exactly the quote I used once in a blog post on science communication in theory and practice – and it even has a picture of me climbing up a ladder! The point: Metaphors are useful, but at some point, they might have to be discarded.

Here I want to bring in one more quote from outside the comments, but it fits in nicely. It’s from a poet, Robert Frost, on metaphor: “All metaphor breaks down somewhere. That is the beauty of it. […] You don’t know how much you can get out of it and when it will cease to yield. It is a very living thing. It is as life itself.” Life scientists take note.

Metaphors, breakdown and theories

Some commenters talked explicitly about the breakdown of metaphors, both in the case of what we call ‘theory constitutive’ metaphors and in the context of pedagogic or communicational metaphors. In each case, and now I quote from a blog post outside my little corpus: “The manner (when, where, how?) by which a metaphor ‘breaks down’ informs us about the ways a metaphor differs from the referent reality — and thereby offers us focus for our insights.”

Metaphors help build scientific theories but this should also involve dropping them if necessary. As one commenter said: “Metaphors are a trick to get your brain to start thinking about something. Understanding a concept often involves finding the places where the metaphor stops working.” Or: “Metaphors help people start to understand a concept, but they don’t help them finish”.

Metaphors, breakdown and communication

Metaphors also help communicate science/theories, but one has to be careful. As one commenter pointed out: “If metaphors are going to work as educational tools we need to know two things about them. The first, obviously, is what they are good at explaining. The real education starts, however, when you can also explain where the metaphor breaks down. If all the breakdown points are trivial you call it a ‘theory’. Kind of… it’s just a metaphor.” This brings us to science communication and its pitfalls.

Communicating with metaphors is really difficult. I have written before that to create a metaphor you need knowledge or at least awareness of two conceptual domains that you then connect, and to understand metaphors you also need knowledge of that kind, and they never perfectly match. That knowledge is also unevenly distributed between people and between source domain (what you take inspiration from) and target domain (what you want to say/find out about). For example, saying “A wetland is a sponge” works for almost everybody, as almost everybody knows both the source and the target domains, while that is not the case with “Hsp90 is a chaperone”. That works well though in a conversation where people know the topic.

One commenter also dealt with this issue based in their own experience: “Well, is the person familiar with the metaphor? I can tell someone that DNA is the source code for a living organism, and RNA is the compiled code… and it’s a great metaphor – for a computer scientist. Everyone else is left scratching their heads. Or, worse yet, what if my hypothetical listener THINKS they understand it; they smile and nod, ask questions and seem to respond like they Get It… and then they ask how to decrypt the code. Oops. Or, they get more caught up in the metaphor than the actual lesson, and I could end up spending an hour explaining compilers and virtual machines, and never get to how DNA works.”

Metaphors and models all the way down

As metaphors in science often deal with stuff that’s completely invisible and, in a sense, indescribable, one commenter said, again, using language I don’t understand, apart from the words ‘metaphor’, ‘model’ and ‘all the way down’:

“What’s that you say, you draw Lewis structures? You should think in terms of hybrid orbitals. What? Oh, yes, you should be looking at that protein from an MO [molecular orbital, I think] perspective. Well, aaaaactually, MOs are nonsense…you really need to think in terms of *states*…. I hate to say it, but ‘it’s metaphors all the way down’. We describe everything in chemistry (which is, after all, the study of a bunch of overlapping wave functions) in terms of metaphors, since we can’t actually see any of it, it *isn’t* like springs, or spheres, or balls and sticks, or whizzing electrons, or any of that at some level. You can have simple models or complex models. They’re all models.” So true!

Metaphors and models are all we have to think about nature. They are, as Andrew Reynolds so memorably said in a book on the history of cell biology, our ‘third lens’, after our eyes and after the microscope. As one commenter rightly wrote: “It’s impossible for our puny minds to comprehend nature without sculpting it into a simplified model. Metaphor is one valuable aspect of that model.”

Scrutinising assumptions

But the commenter also warns us to be wary of metaphors, referring implicitly to an article by Thibodeau and Boroditsky on metaphors and their social consequences, which Philip Ball had mentioned in an article entitled “A metaphor too far” for Nature, which Derek Lowe had mentioned in his commentary: “In science, it is vital that we re-evaluate our assumptions, whether they are assumptions of the experiment or of the nomenclature. If we call crime a ‘virus’, ask how we might treat it differently if it were a ‘beast’. I think that may be the most important quality we learn in our education, and probably not just in the scientific fields.”

This reminded me of what I had said about Reynold’s ‘metaphors in the life sciences’ book: “Reynolds makes clear that far from being mere decorative devices, metaphors are more like scientific hypotheses. They are always partial and provisional and need to be kept under constant scrutiny and revised when new evidence emerges. They are, I would add, similar to models in being mostly wrong but sometimes useful. When mapping knowledge from a familiar source onto an unfamiliar target, the match is never perfect. There is always a crack. That’s where the light gets in, as Leonard Cohen would say; that’s where science happens.”

The good, the bad and the true

So, there are metaphors that make you see things in a new light; there are metaphors that plant a picture in your mind that you can’t shift; there a metaphors that help move a theory forward but eventually break down and there are metaphors that are useful in science communication and others that are not.

One commenter, and this is my last offering, attempted to sort metaphors in to good ones, bad ones and true ones, but unfortunately the commenter didn’t provide a nice example for each category – can you, readers, think of some?

“I think you can separate them into a 2×2 grid:
I: Easy; Explains Lots (good metaphor)
II: Hard; Explains Lots (too true to be good)
III: Easy; Explains Little (too good to be true)
IV: Hard; Explains Little (bad metaphor)
Obviously, you want lots of Type I metaphors. You don’t ever want Type IV metaphors (those are the bad ones). Early in our careers, we rely mostly on I and III, and as we become more sophisticated, we lean more on I and II. There’s often an inverse correlation between how ‘true’ a metaphor is, and how easy it is to understand its uses. Good scientists move up and down this ladder, and grow comfortable with holding multiple metaphors in their head at once.”

That’s all we can do, because, as another commenter noted: “Language is a pretty inexact tool for conveying concepts — except we don’t have anything better.” In a way though, the imperfections of language drives knowledge acquisition. If language was perfect, this would stop. Put that in your pipe and smoke it, Leibniz!

And that brings us back to something Buzz Baum said on Twitter: “We think in metaphors. Is there anything that is what we think it us [is]? The important question is when is the metaphor useful and when is it confusing? When is a new metaphor needed? Translation is a brilliant metaphor. As is Transcription. Evolutionary Capacitor, less so.” Don’t ask me what a capacitor is!

Breaking down is good to do

I found it fascinating to listen in to what actual scientists actually say about metaphor, rather than speculating about metaphors and science in a glorious vacuum. I have only looked at a bit of Twitter and a few comments underneath a commentary. There is probably so much more out there one could explore. One thing I have learned from all this is: Science advances when metaphors fail and science stalls when metaphors go stale.

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