One of the FallaciousArgument''''''s.

The fallacy that A!=B and A!=C, therefore B=C.

Often used in political debates. Speaker asserts that two political parties/persons/factions are a) different from him (or his party); and b) alike in some way (e.g., "leftist" or "right-wing"), so they are the same or equivalent. Frequently, B is the speaker's opponent (or the opponent's political affiliation), or something else that the speaker wishes to discredit, and C is a widely-repudiated group or individual that represents an extreme viewpoint (Nazis/Hitler, Communists/Stalin, the Klan, bin Laden, etc.). Purpose is to associate B's views (which may be regarded as "reasonable") with those of C.

''The enemy of my enemy is my friend. Sounds like a plan for foreign policy to me.'' Sounds like polarization to me.  ''My favourite term for it is "triangulation".''

  -- "The enemy of my enemy is my enemy's enemy. Nothing more, nothing less." (Howard Taylor) 
History is full of examples where a nation had two sets of opponents which were themselves at war with each other. Alliances and coalitions are the exception, not the rule. -- JayOsako

----

Example: Minivans are vehicles, but different from Cars.  Trucks are vehicles, but different Cars.  Minivans and Trucks are both not Cars.  Therefore, Minivans are a lot like Trucks.

To see that this reasoning is flawed, substitute Bicycle for Truck.

----

This has a corollary.  I disagree with both B and C.  However, the opinions of B and C contradict each other.  Therefore they are both wrong and I'm right.

----
See in the wild with: Republicans are not liberals. Republicans are not Democrats. Therefore liberals are Democrats. ''(I'm not sure if Democrat or liberal is the more "derogatory" term)''

----
See also YouAreNotEveryone