Analogy and Argument from Analogy in Science
Despite that in science an analogy is considered a legitimate device in process of searching for scientific explanation of phenomena under investigation (i.e. it has a legitimate heuristic use), it cannot serve as proof. Analogies are also suggestive; however the suggestions they make are often the source of errors which would otherwise have been avoided. Darwin has been often criticised for using the argument from analogy as substitute for scientific observation. From analogy he moved to using metaphor (poetic device)[note 1] and imaginary examples such as an absurd and fantastic transformation from bears into whalelike animals owing to insects in the water functioning as the selector in the environment.
How to tell you have an analogy
It is sometimes difficult to diagnose exactly what an analogy is. Sometimes you will be confused as to whether you have a simple comparison, or an actual analogy. For instance, to say that you have a bike, which is like your friend's bike. This is a comparison, because you're not describing a different type of object to your bike, but instead, comparing your bike to another like object.
Now, an analogy would be to say that an airsoft gun is like a real gun, except that it shoots plastic pellets instead of lead bullets like a gun should.
- cf."Methaphorical statements are not true or false, but merely apt or inapt, appropriate or inappropriate. Scientific statements make truth claims and therefore cannot be methaphorical."
- W. H. Leatherdale (1974). The role of analogy, model, and metaphor in science. North-Holland Pub. Co.. ISBN 9780720480221.
- Patrice Debré (1998). Louis Pasteur. The Johns Hopkins University Press, 260. ISBN 978-0801-865299. “Pasteur...went up to ... offer his criticism:...Analogy cannot serve as proof.”
- E.J. Larson (2006). Evolution: The Remarkable History of a Scientific Theory. New York: Modern Library, 84. ISBN 0-8129-6849-2. “Darwin began his argument with an analogy. ... Building on this analogy, Darwin then turned to wild plants and animals. ... Lacking understanding of modern genetics and conceding that "our ignorance of the laws of variation is profound," Darwin speculated that innate differences among individuals often came from ... Of course, he did not understand heredity.”
- Randal Hedtke (2010). "An analysis of Darwin's Natural-Selection, Artificial-Selection Analogy: Critique of the Analogy", Secrets of the Sixth Edition. Master Books, 79–102. ISBN 978-0-89051-597-6. “... Arguments from Analogy may be fertile but they are all invalid.”