RationalWiki's 2020 Fundraiser

There is no RationalWiki without you. We are a small non-profit with no staff – we are hundreds of volunteers who document pseudoscience and crankery around the world every day. We will never allow ads because we must remain independent. We cannot rely on big donors with corresponding big agendas. We are not the largest website around, but we believe we play an important role in defending truth and objectivity.

If everyone who saw this today donated $5, we would meet our goal for 2021.

Fighting pseudoscience isn't free.
We are 100% user-supported! Help and donate $5, $20 or whatever you can today with PayPal Logo.png!

Donations so far: $1680Goal: $3500

Extended analogy

From RationalWiki
Jump to: navigation, search
Cogito ergo sum
Logic and rhetoric
Icon logic.svg
Key articles
General logic
Bad logic

Extended analogy is a logical fallacy where the use of an analogy (a rhetorical device used to compare the same phenomenon in different contexts for emphasis or clarification) in a discussion of a general rule is taken to be a statement that the scenario in the analogy and the scenario in the original argument are alike in additional ways. It is a fallacy of distraction.


The fallacy occurs by processing an analogy in the following way:

P1: A is like X in some way.
P2: B is like X in a different way.
C: Therefore, A is like B.

The fallacy will focus on unacceptable aspects of the final line in order to ignore the purpose of the comparison. For example:

Person N: "Software pirates should campaign to change the law and not break it. I don't think it's ever valid to oppose the law by breaking it."
Person M: "Such a position is odious: it implies you would not have supported the women's suffrage movement."
Person N: "Are you suggesting piracy is as important as giving women the vote? How dare you!"

M's analogy is a valid reductio ad absurdum response to the original argument (that it is never acceptable to break the law while opposing it), but N's reply instead assumes M's analogy is a claim both acts are equally significant.