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2. Reason / E. Argument / 3. Analogy

[attempting proof by comparison with similar cases]

8 ideas
Some things cannot be defined, and only an analogy can be given [Aristotle]
     Full Idea: It is not right to seem a definition for everything - for some things an overview is to be had by analogy.
     From: Aristotle (Metaphysics [c.324 BCE], 1048a33)
     A reaction: This is what David Lewis called the 'way of example' in defining what is meant by 'abstract objects'.
All reasoning concerning matters of fact is based on analogy (with similar results of similar causes) [Hume]
     Full Idea: All our reasonings concerning matters of fact are founded on a species of analogy, which leads us to expect from any cause the same events, which we have observed to result from similar causes.
     From: David Hume (Enquiry Conc Human Understanding [1748], §82)
     A reaction: Interesting. Analogy notoriously becomes problematical when you have only one case (or a few) to go on, as when inferring other minds, or God's existence from natural design.
An analogy begins to break down as soon as the two cases differ [Hume]
     Full Idea: But wherever you depart, in the least, from the similarity of the cases, you diminish proportionably the evidence; and may at last bring it to a very weak analogy.
     From: David Hume (Dialogues Concerning Natural Religion [1751], Part 2)
Philosophical examples rarely fit rules properly, and lead to inflexibility [Kant]
     Full Idea: Giving examples most commonly damages the insight of the understanding, since they only seldom fulfil the condition of the rule under consideration, ..and in the end accustom us to use those rules more like formulas than like principles.
     From: Immanuel Kant (Critique of Pure Reason [1781], B173/A134)
     A reaction: This is directly contrary to the belief of most people who study or teach philosophy in the English-speaking world, but it is an interesting challenge. Philosophy is mainly concerned with abstract ideas. Maybe we need many examples, or none.
You can't infer that because you have a hidden birth-mark, everybody else does [Ayer]
     Full Idea: My knowing that I had a hidden birth-mark would not entitle me to infer with any great degree of confidence that the same was true of everybody else.
     From: A.J. Ayer (The Central Questions of Philosophy [1973], §VI.E)
     A reaction: This is the notorious 'induction from a single case' which was used by Mill to prove that other minds exist. It is a very nice illustration of the weakness of arguments from analogy. Probably analogy on its own is useless, but is a key part of induction.
Legal reasoning is analogical, not deductive [Fogelin]
     Full Idea: There is almost universal agreement that legal reasoning is fundamentally analogical, not deductive, in character.
     From: Robert Fogelin (Walking the Tightrope of Reason [2003], Ch.2)
     A reaction: This raises the question of whether analogy can be considered as 'reasoning' in itself. How do you compare the examples? Could you compare two examples if you lacked language, or rules, or a scale of values?
Babylonian thinking used analogy, rather than deduction or induction [Watson]
     Full Idea: In Babylon thought seems to have worked mainly by analogy, rather than by the deductive or inductive processes we use in the modern world.
     From: Peter Watson (Ideas [2005], Ch.04)
     A reaction: Analogy seems to be closely related to induction, if it is comparing instances of something. Given their developments in maths and astronomy, they can't have been complete strangers to the 'modern' way of thought.
Don't trust analogies; they are no more than a guideline [Halbach]
     Full Idea: Arguments from analogy are to be distrusted: at best they can serve as heuristics.
     From: Volker Halbach (Axiomatic Theories of Truth [2011], 4)