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Thu Dec 19, 2013, 11:18 AM

I need a name for a logical fallacy

The fallacy is because Person <X> agrees with Person <Y> on Subject <A>, they must also agree on Subject <B>.

I came across this one in a discussion with a libertarian, when I told him that the first socialized medicine program was instituted by Otto von Bismarck, in part because he agreed with the Socialists that socialized medicine would be good for Germany. The libertarian then said that Bismarck must have been a socialist.

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Reply I need a name for a logical fallacy (Original post)
Fortinbras Armstrong Dec 2013 OP
Galileo126 Dec 2013 #1
Fortinbras Armstrong Dec 2013 #3
rrneck Dec 2013 #2
kairos12 May 2014 #4


Response to Galileo126 (Reply #1)

Fri Dec 20, 2013, 06:33 AM

3. I looked there, thanks

I also went to a few other sites -- TV Tropes, of all places, had a good list.

I might call it a hasty generalization, or perhaps an overgeneralization, but I'd really like something more specific.

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Response to Fortinbras Armstrong (Original post)

Thu Dec 19, 2013, 11:32 AM

2. Sounds like Affirming the consequent

But I'm not much of a logician.




http://en.wikipedia.org/wiki/Affirming_the_consequent

Affirming the consequent, sometimes called converse error or fallacy of the converse, is a formal fallacy of inferring the converse from the original statement. The corresponding argument has the general form:

If P, then Q.
Q.
Therefore, P.

An argument of this form is invalid, i.e., the conclusion can be false even when statements 1 and 2 are true. Since P was never asserted as the only sufficient condition for Q, other factors could account for Q (while P was false).[1]

To put it differently, if P implies Q, the only inference that can be made is non-Q implies non-P. (Non-P and non-Q designate the opposite propositions to P and Q.) Symbolically:

(P ⇒ Q) ⇔ (non-Q ⇒ non-P)

The name affirming the consequent derives from the premise Q, which affirms the "then" clause of the conditional premise.


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Response to Fortinbras Armstrong (Original post)

Fri May 9, 2014, 01:48 PM

4. Bismark was a political realist. He needed a pressure relief valve

from the social pressures that were sweeping Europe. He used his socialized medicine program as a way to do this. It makes him a pragmatist, not a socialist.

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