What is an analogy?

What is an analogy?
The body
Before birth


"Analogies prove nothing, that is quite true, but they can make one feel more at home."
Sigmund Freud, New Introductory Lectures on Psychoanalysis (1913)


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There are several words with similar and often overlapping meanings:

bulletanalogy - a similarity is pointed out between one thing and another
bulletmetaphor - something that represents something else, a symbol
bulletallegory - an extended metaphor that details key attributes of the subject, perhaps in story form
bulletscientific model - this is a conceptual framework that captures the essence of a more complicated natural system
bulletsimile - a simile says something is 'like' something else

I shall be using 'analogy', 'metaphor', and 'model' quite freely in these pages, and not worrying too much about precise definitions.

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The central premise of this web resource is that biological concepts have resonances and parallels with everyday experience. This is by no means a new idea - analogy, metaphor and modelling have long played a useful part in the development of biological and other scientific ideas, and teachers regularly draw on analogies to help students understand more readily. My approach will be to seek out useful analogies that hopefully will make the initial learning of biological concepts a more natural process.

A good analogy helps us understand new concepts - it is like a bridge from what we know across into the unknown. I believe that analogies can have this role because at a deep level there are repeating patterns in nature. Patterns of structures and processes that we are familiar with at the human level can also be recognised at other levels of organisation. For example, we live within communities and learn that we have freedoms, constraints, and responsibilities in relation to what we do. We have to balance our personal wants and wishes with the common good. Cells which form the body also live within communities, and have to balance their personal behaviour with the needs of the community. So we can use the metaphor of human community as a way of understanding cellular communities. I shall do this for example when considering the development of the embryo, or the cellular events during inflammation.

Analogy requires us to map from one system to another system. We are looking for relationships that resonate, rather than worrying about the details of what materials the systems are made of or which scale of size or complexity they have. There is an area of science and philosophy known as general systems theory which deals with these common denominators and repeating patterns. (There is a note about systems theory here.) It follows that by understanding something at one level, we can usefully apply that knowledge when we study other levels. As William Blake expressed it: "To see a World in a grain of sand". However, an analogy cannot be a perfect match in every regard, so the teacher carries the responsibility of pointing out the limits of the analogy as well as its strengths.

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