“Take an economics class,” and variations such as “someone's never taken an economics class” or “you people need to study economics,” is a phrase one sees often in any political debate forum on the Internet. Usually it appears in reply to a message that the poster feels (correctly or not) betrays a fundamental lack of understanding of economics. In these cases it may also be accompanied by some short oversimplification of some economic concept in the form of a sentence fragment. For example: “Supply and demand, jeez! Come back after you take an economics class!”

Most use of “take an economics class” is dismissive. It usually appears with little accompanying argument. The poster is assuming that the truth of whatever that their target has been arguing against is self-evident given knowledge of economics. While use of the phrase is not an indicator one way or the other as to the correctness of the poster's ideas, it does indicate that the poster is unwilling or unable to coherently explain why their target is wrong, either due to laziness, or due to not actually understanding the subject matter themselves. But to reinforce their superiority without actually defining it, they malign the target's education.

Economics is the subject most often found in “take a >blank< class,” but it can be anything. People who fancy themselves (rightly or not) experts on a subject just dismiss an opinion with which they disagree by suggesting a reason for it (lack of education required to understand it) without even giving any indication of what the supposed flaw in the opinion was. This leaves those who (even if they are right, or at least not blatantly wrong) are laymen who have not had this education in the position of defending their opinion not knowing what is supposedly wrong with it, and possibly acknowledging the lack of education on the subject, which (again, whether they are right or wrong) gives the “TAEC” the appearance of having won, because they are the knowing insider, and the other poster is the unknowing outsider. All this without ever having to have addressed the content of the opinion they are opposing.

While use of "take an economics class" may not be inherently unfair, as in cases where it is directed as a repetetively and obstinantly ignorant poster whose points have been dissected without acknowledgment, in practice it is usually about equal parts appeal to authority, red herring, and ad hominem.

The only effective counter to this is to either be a bona fide expert in the subject who can accurately take the “TAEC” poster to task for every single one of THEIR errors; or to call the “TAEC” poster's bluff and explain the game that is being played to anyone else. Note, this is not a good idea if you know for a fact that you don't know what you're talking about and were just taking a shot in the dark without acknowledging it as such. And it likely won't work in a forum driven primarily by emotion, or among those who are rigidly dogmatic where you are going against the prevailing dogma.