Keith S. Taber
It is something of a cliché, so it was not the phrase itself ("…that's my theory anyway and I'm sticking to it") that caught my attention, but that I heard it used by a scientist.
The duvet cover mystery
Dr Penny Sarchet, Managing Editor of New Scientist was talking on an episode ('Answers to Your Science Questions') of BBC Inside Science, where a panel were presented with listener's questions.
Dr Sarchet was responding the query:
why, when I put a duvet cover in the washing machine with other items, they all end up inside the duvet cover when the programme finishes
Now this is a phenomenon I have observed myself, and I was not sure of the explanation. As it happened, Dr Sarchet had also wondered about this, indeed she had apparently "thought about this on a weekly basis for as long as I can remember", and had a – well let me say for the moment – suggestion.
The suggestion was that
"what might be going on here is, obviously when you've got a duvet cover and if you have not sort of buttoned it up before putting it in the wash, you've got a very wide opening, so that's easy statistically for things to enter it, and then as it twists around in the wash, it's actually harder to leave. So, what you've got is kind of a difficulty gradient, things are more likely to go in than they are to come out; and my reckoning is if that keeps happening for a long enough period, enough cycles, eventually everything ends up inside."
Now, I tried to visualise this, and was not convinced. In my mental simulation, the configuration of the duvet cover is such that:
- initially, ingress and egress are both readily possible; then,
- as twisting begins, possible but less readily; then,
- when the duvet becomes very twisted, both ingress and egress are blocked.
There seems to be a 'difficulty gradient' over time, but in my mind this seemed symmetrical in relation to the direction of passage – moving in and out of the duvet cover. Perhaps some items will enter the duvet before the passage is closed – but why should this be all of them, if items can leave as well as enter up to that point?
I am not sure I am right here because I might just be lacking sufficient creative simulation capacity (imagination), or I may not have fully appreciated the mechanism being suggested. After all, a communicator has a meaning in mind, but the text produced (what they say or write, etc.) only represents that meaning and does not inherently contain it. It is up to the audience to make good sense of it. Perhaps I failed. After all, the phenomenon seems to be a real one, so something is going on.
Analogy in scientific discovery
But what intrigued me about the suggestion was less its veracity, but rather two features of how it was presented. As my heading suggests, Dr Sarchet closed here proposal with the statement that "that's my theory anyway and I'm sticking to it". She prefaced her proposal by reporting on its origin:
"I'd like to argue this might be a little bit like cell biology…"
Dr Sarchet is a biologist, with her doctorate in development genetics, and I thought it was interesting that she was making sense of washing dynamics in terms of cells. Interesting, but not strange: we all seek to make sense of things, and to do so we draw on the range of interpretive resources we have available – the knowledge and understanding, language, images, experiences, and so forth that we carry around represented in our heads. That a biologist might derive a suggestion from a biological source therefore seems quite natural.
Moreover, the process operating is one that is common in science itself. The process I refer to is that of analogy,
"the reason I kind of try to claim that's like cell biology is sometimes, certain substance, it is much easier for them to get into the cell, through the cell membrane because of the way it is made than it is for them to randomly diffuse out again. And that's a really sort of clever, not kind of actively driven way, of creating order"
I have written a lot about analogy on this site, but mostly in relation to science teaching and science communication more widely. That is, how teachers 'make the unfamiliar familiar' by suggesting that some abstract notion to be learnt is actually, in some way, just like something the learners are already familiar and quite comfortable with – it is like a ladder, or the high jump, or the way people arrange themselves sitting on a bus, or like water passing through a drain hole, or whatever.
However analogy is also actually used within scientific practice itself, in the discovery process. Perhaps we should not be surprised then that analogies are often found when scientists talk or write about their work, as well as commonly being used by journalists and authors of popular science books.
Read examples of scientific analogies
Sometimes the use of analogy within science itself may be making such small jumps that we may not notice analogy is being used:
Element X is in the same group of the periodic table as element Y, and element Y forms a compound with element A with the properties I am interested in, so I wonder if element X also forms a compound with element A with those properties?
Sometimes however, the jumps are across topics or even sciences.
Does this strange new property of the atomic nucleus suggest the nucleus can behave a bit like a drop of liquid; and, if so, can ideas from the physics of fluids be useful in this different area of nuclear physics?
In this way, the recognition of a potential analogy suggests conjectures that can be tested. Use of such analogies is therefore part of the creative aspect of science.
Perhaps the ultimate use of analogy occurs in physics where equations are found to transfer from one context to another with the right substitutions (e.g., 'it's a wave phenomenon, so we can apply this set of equations that work for all wave phenomena'). As learners will find if they continue with physics as an elective school subject:
We have an equation for the flow of charge in an electrical conductor, and fluid flows, so the same basic equation could work there. And we talk of heat flow, so we should be able to adopt the same basic equation…
I once designed a teaching activity for upper secondary learners (Taber, 2011a) based about the ways certain phenomena are analogous in the sense of following exponential decays (e.g., capacity discharge, radioactive decay, cooling…). For learners not yet introduced to the exponential decay equation this analogy can be built upon the common feature of a negative feedback loop where the magnitude of a driver (excess temperature, radioactive material, p.d.) is reduced by the effect it drives (heat, radioactivity, current);
An exponential decay occurs when a negative feedback loop operates.
In capacitor discharge, A could be p.d. across capacitor, and B current (+ indicates the more p.d. across the plates, the more current flows; – indicates the more current flows {removing charge from the plates}, the lower the p.d. across the plates).
As p.d. falls, the current falls (and so the rate of drop of charge across plates fall) and so the rate of p.d. dropping also falls. …
Similar arguments apply to radioactivity and amount of radioactive material; and cooling and excess temperature.
Read about the activity: Identifying patterns in science
Progress in science relies on empirical studies to test ideas: but empirical tests can only be carried out after an act of creative imagination has produced a hypothesis to test. Because science is rightly seen as rational and logical, we can easily lose sight of the creative aspect:
"Creativity is certainly a central part of science, and indeed part of the expectation of the major qualification for any researcher, the Ph.D. degree, is that work should be original. Originality in this context, means offering something that is new to the literature in the field concerned. The originality may be of various kinds: applying existing ideas in a novel context; developing new instrumentation or analytical techniques; offering a new synthesis of disparate literature and so forth. However, the key is there needs to be some novelty. Arthur Koestler argued that science, art, and humour, all relied on the same creative processes of bringing together previously unrelated ideas into a new juxtaposition."
Taber, 2011b
Science teaching needs to reflect how science is creative and so open to speculative divergent thought (as well as being logical and needing disciplined convergent thinking!)
"Science teachers need to celebrate the creative aspects of science – the context of discovery. They should emphasise
- how scientific models are thinking tools created by scientists for exploring our understanding of phenomena;
- how teaching models are speculative attempts to 'make the unfamiliar familiar' by suggesting that 'in some ways it's a bit like something you already know about'; and in particular
- how scientists always have to trust imagination as a source of ideas that may lead to discovery.
However, it is equally important that the creative act is always tempered by critical reflection. Scientific models have limitations; teaching models and analogies may be misleading; and all of us have to select carefully from among the many imaginative possibilities we can generate if we seek ideas that help us understand rather than just fantasise."
Taber, 2011b
That's not your theory!
But the other point I noted, which I raised at the beginning of this piece, was how Dr Sarchet signed off "…that's my theory anyway and I'm sticking to it" which from a scientific perspective seemed problematic at two levels.
I am not being critical of Dr Sarchet as she was just using a chiché in a humorous vein, and I am sure was not expecting to be taken seriously. Other scientists listening to the programme will have surely realised that. I am not so sure if lay people, or school age learners, will have picked up on the humour though.
As a scientist, Dr Sarchet would, I am sure, acknowledge the provisional nature of scientific knowledge: all our theories are open to being replaced if new evidence or new ways of understanding the evidence suggest they are inadequate. Scientists, being human, do get attached to their 'pet' theories, but a good scientist should be prepared to give up an idea and move on when this is indicated. Scientists should not 'stick to' a theory come what may. Just as well, or we would still be operating with phlogiston, caloric and the aether.
Read about historical scientific conceptions
But in any case, I am not convinced that Dr Sarchet had a theory here. A theory is more than an isolated idea – a theory is usually more extensive, a framework connecting related concepts, perhaps encompassing one or more empirical generalisations (laws), and being supported by a body of evidence.
What Dr Sarchet had was a conjecture or hypothesis that she had not yet tested. Certainly having a testable hypothesis is an important starting point for developing a theory – but it is not sufficient.
The hypothesis of continental drift was proposed decades before sufficient investigations and evidence led to the modern theory of tectonics. This is the general situation: the hypothesis or conjecture is a critical step, but by itself does not lead to new knowledge.
Common conceptions of scientific theories
I do not imagine Dr Sarchet really considered her suggestion had reached theory status either. Again, she was just using a common expression. But this is just one example of how words that have precise technical meanings in science (element, energy, force, momentum, plant, substance…) are used with more flexible and fluid meanings in everyday life.
For most people, a 'theory' (let me denote this theorylifeworld to mean how the word is used in everyday discourse) is nothing special – we all have theorieslifeworld all the time. Perhaps a theorylifeworld that a particular football team will win on Saturday, or that next door's cat hates you, or that they are putting less biscuits in these packets than they used to. A theorylifeworld can be produced with little effort, held with various degrees of commitment (often quickly forgotten when experience does not fit, but sometimes 'stuck to' regardless!) and often abandoned with little cost.
Now scientific theories are not like that. In one curriculum context, theoriesscience were defined as 'consistent, comprehensive, coherent and extensively evidenced explanations of aspects of the natural world'. But, if learners come to class having long heard and used the term 'theory' with its 'lifeworld' (that is, everyday, informal) meaning then they think they already know what a theory is (and it is not a consistent, comprehensive, coherent and extensively evidenced source of explanations of aspects of the natural world!)
This is not just speculation, as studies have asked school age learners how they understand such terms. One study, undertaken in that curriculum context that suggested theories are 'consistent, comprehensive, coherent and extensively evidenced explanations of aspects of the natural world' found most respondents had quite a different idea (Taber, et al., 2015). They generally saw a theory as something a scientist made up effortlessly (almost on a whim). Accordingly, they did not think that theories had a very high status – as they had not yet been tested in any way. Once tested, any 'theory' that passed the test ceased to be a theory – perhaps becoming a law: something seen as proven and having (unlike the theory) high epistemological status.
This common pattern is caricatured in the figure:
So, laws were seen as of higher status than theories. Laws were proven and so not open to questioning (that is, their conjectural nature as generalisations that could never be proven were not recognised), whereas theories were little more than the romanced flotsam and jetsam of someone's imagination.
It is just a theory
Now of course, I am generalising here from a small sample (of 13-14 year olds learners from a few schools in one country) and individual learners have their own nuanced understandings – aligned to the curriculum account to different degrees.
One interviewed learner confused theories with theorems from mathematics . But, as a generalisation, the learners interviewed tended to see a theory much more as a hypotheses or conjecture than as a worked through conceptual framework of related ideas that are usually supported by a range of evidence, often collected by deliberate testing.
This is useful for the teacher to bear in mind as clearly when the teacher refers to theory, the learners will often understand this as something quite different from what was intended. Probably the only response to this is to review the intended meaning of 'scientific theory' each time one is discussed. Learners can overcome their alternative conceptions with sufficient support and engagement, but the teacher has to work hard when the existing idea is not only long-established but also being reinforced by everyday discourse (and scientists in the media such as Dr Sarchet shifting to the vernacular, as non-scientists may not recognise the transition from a technical to an everyday code).
So, for example , the theory of natural selection (or general relativity if you prefer), is not proven because in science we can never prove general ideas, and so it is just a theory. But theories are all we are ever going to get in science (for certainties look elsewhere), and some of them are so well tested and supported that in practice we treat them as secure and almost as if certain knowledge.
Perhaps it does not matter enormously if many learners leave school thinking general relativity is only a theorylifeworld. Perhaps it does not even matter that much for many learners if they leave school thinking natural selection is only a theorylifeworld. But when people dismiss climate change or the basis of vaccination as 'just a theory' this is much more problematic, as it invites an attitude that these 'consistent, comprehensive, coherent and extensively evidenced explanations of aspects of the natural world' are of no more merit than your neighbour's 'theory' about the next set of winning lottery numbers or a politician's 'theory' about the merits of high import tariffs for reducing the price of eggs. And that is a problem, as climate change and vaccination really matter – critical to individual and collective survival.
At least, that's my theory, and I'm sticking to it.
Work cited:
- Taber, K. S. (2011a). Patterns in nature: challenging secondary students to learn about physical laws. Physics Education, 46(1), 80-89. https://doi.org/10.1088/0031-9120/46/1/010 [Download this paper]
- Taber, K. S. (2011b). The natures of scientific thinking: creativity as the handmaiden to logic in the development of public and personal knowledge. In M. S. Khine (Ed.), Advances in the Nature of Science Research – Concepts and Methodologies (pp. 51-74). Dordrecht: Springer. [Download this chapter]
- Taber, K. S., Billingsley, B., Riga, F., & Newdick, H. (2015). English secondary students' thinking about the status of scientific theories: consistent, comprehensive, coherent and extensively evidenced explanations of aspects of the natural world – or just 'an idea someone has'. The Curriculum Journal, 1-34. doi: 10.1080/09585176.2015.1043926 [Download this paper]
The book Student Thinking and Learning in Science: Perspectives on the Nature and Development of Learners' Ideas gives an account of the nature of learners' conceptions, and how they develop, and how teachers can plan teaching accordingly.
It includes many examples of student alternative conceptions in science topics.
