This type of reasoning is used to explain difficult, obscure concepts through simpler, more commonly known or accessible ones. The difficult concept is said to be like the simpler one in some way, with differing parts of them equated on a 1:1 basis, and so is an understanding communicated.
An example:
Bill is trying to teach an end-user Cathy how to prevent security breaches, particularly those caused by a specific type malicious software. Luckily there is a common biological analogy built into their very name: viruses. He explains how computer viruses behave like biological viruses, hijacking their host’s resources and creating more copies of themselves.
He explains how prevention is much the same: practicing good hygiene by staying away from potential sources of infection and regularly ‘cleansing’ the computer using an anti-virus program, as well as avoiding sticking things of unknown provenance and potential infection into the computer.
Analogy has been especially useful to science not just in explaining concepts to the wider public, but in the solving and discovery of some of the most iconic and world-shattering facts and concepts. Most famously, Einstein figured out the effect of time dilation implied by his theory of Special Relativity by picturing a train moving at close to the speed of light and a flashlight being turned on inside it. It’s too involved to get into detail here, but look it up. It’s absolutely fascinating.
Neils Bohr, the “father of the atom” figured out the structure of atoms by imagining himself sitting on the sun, with the planets zipping around in their orbits – the sun is analogous to the nucleus, and the planets to the electrons. German chemist August Kekulé figured out the ring structure of the molecule benzene when he dreamt of a snake eating its own tail.
As already hinted, analogy is particularly useful when you wish to communicate to your opponent a concept that you are familiar with but they are not, be it technical or experiential, through comparing it to something you both understand. The reason it works so well is because our brain works through association – the recognition of patterns. This is the same pitfall that leads to butterfly logic, but used in a completely different way for a much more constructive end.
The most obvious shortcoming of analogy is, of course, that the two situations being likened are not necessarily equivalent in every aspect, to varying degrees. You have to make sure that you not only fully understand how the complex subject you are trying to simplify works, but also exactly how it relates to the simpler one you are comparing it to. Acknowledging the points where the two are not precisely alike can serve to increase your credibility with your opponent.
