A gadfly is a person who interferes with the status quo of a society or community by posing novel, potentially upsetting questions, usually directed at authorities.
The term "gadfly" (Ancient Greek: μύωψ[1], mýops[2]) was used by Plato in the Apology[3] to describe Socrates' acting as an uncomfortable goad to the Athenian political scene, like a spur or biting fly arousing a sluggish horse.
During his defense when on trial for his life, Socrates, according to Plato's account, pointed out that dissent, like the gadfly, was easy to swat, but the cost to society of silencing individuals who were irritating could be very high: "If you kill a man like me, you will injure yourselves more than you will injure me" because his role was comparable to that of a gadfly: "to sting people and whip them into a fury, all in the service of truth".
[4] Dominic Scott notes that in the Apology, the allusion speaks well of Socrates, whereas in the Meno, the image which compares Socrates to a stingray who "numbs" his interlocutors into silence and confusion has the opposite effect.
[6] For example, Morris Kline wrote, "There is a function for the gadfly who poses questions that many specialists would like to overlook.