what fallacy is : On the Colbert Report, Steven Colbert regulary asked his guests: "George W Bush: a great president? or the greatest president?

http://writingcenter.unc.edu/handouts/fallacies/

Let us know what you decide.

The fallacy in this statement is known as a loaded question or a complex question fallacy. It is a type of fallacy that tries to trap the person being questioned by assuming something that may not be true or by presenting a false dichotomy.

To identify this fallacy, you need to recognize that the question is structured in a way that only offers two extreme options: "a great president" or "the greatest president." By phrasing the question this way, it assumes that George W. Bush must be either one or the other, disregarding any other possibilities or options.

To avoid falling for this fallacy, you should be cautious of loaded or complex questions that push you towards certain predetermined answers. You can respond by challenging the underlying assumption or by reframing the question to allow for more nuanced responses.