A parade of horribles is both a literal parade and a rhetorical device.

As a literal parade

Parade of horribles originally referred to a literal parade of people wearing comic and grotesque costumes, rather like the Philadelphia Mummers' Parade. It was a traditional feature of Fourth-of-July parades in parts of the U. S. in the nineteenth century. As of 2005, some communities, notably Chepachet, Rhode Island continue to have it.

As a rhetorical device

A parade of horribles is also a rhetorical device whereby the speaker argues against taking a certain course of action by listing a number of extremely undesirable events which will ostensibly result from the action. Its power lies in the emotional impact of the unpleasant predictions; however, a parade of horribles is a logical fallacy insofar as:

• The "horribles" are not likely to occur as a result of the action,
• The argument relies solely on the emotional impact of the "horribles," or
• The "horribles" are not actually bad.

A parade of horribles is a type of hyperbole because it exaggerates the negative results of the action. It is similar to a slippery slope argument, but not identical. Whereas a slippery slope argument argues that, "If we do this, then the next thing we do will be this," a parade of horribles argues that, "If we do this, then ultimately all these horrible things will happen."

Examples:

• "If we legalize marijuana, then all of our kids will be smoking it in classrooms, rot their brains, and the country will fall apart!"
• "[Granting the rights of citizenship to blacks] would give to persons of the negro race, ... the right to enter every other State whenever they pleased, ... the full liberty of speech in public and in private upon all subjects upon which its own citizens might speak; to hold public meetings upon political affairs, and to keep and carry arms wherever they went." Dred Scott v. Sandford, , 417, 450-451 (describing the ostensibly horrible results of granting blacks citizenship for purposes of filing suit for their freedom).