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Home > Quote from "On the Natural Classification of Arguments"
Commens
Digital Companion to C. S. Peirce
‘Analogy’ (pub. 06.01.13-19:35). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from http://www.commens.org/dictionary/entry/quote-natural-classification-arguments.
Term: 
Analogy
Quote: 

The formula of analogy is as follows:-

S’, S”, and S”’ are taken at random from such a class that their characters at random are such as P’, P”, P”’.
t is P’, P”, and P”’.
S’, S”, and S”’ are q;
.·. t is q.

Such an argument is double. It combines the two following:-

1

S’, S”, S”’ are taken as being P’, P”, P”’.
S’, S”, S”’ are q.
.·. (By induction) P’, P”, P”’ is q.

t is P’, P”, P”’.
.·. (Deductively) t is q.

2

S’, S”, S”’ are, for instance, P’, P”, P”’.
t is P’, P”, P”’;
.·. (By hypothesis) t has the common characters of S’, S”, S”’.

S’, S”, S”’ are q.
.·. (Deductively) t is q.

Owing to its double character, analogy is very strong with only a moderate number of instances.

Source: 
Peirce, C. S. (1867). On the Natural Classification of Arguments. Proceedings of the American Academy of Arts and Sciences, 7, 261-287.
References: 
W 2:46-47; CP 2.513
Date of Quote: 
1867
URL: 

http://www.commens.org/dictionary/entry/quote-natural-classification-arguments