The fallacy of ergo decedo (or "traitorous critic fallacy") occurs in a debate between members of a group, when an internal criticism is rejected by telling the critic to leave the group, rather than by responding to the substance of the criticism itself.

Here is an example:

Senator A: "If we Republicans want to really serve our constituents, we need to reconsider our platform on this issue."

Senator B: "If you don't like our current platform, then you don't really belong with us, and you should just leave the party."

Note that Senator A's proposal itself has not been addressed at all. Note further that "Republican" could be replaced with any other political party.

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