Sophistry
No. 16 Fallacy

Slippery Slope

Claim one small step inevitably leads to an extreme outcome, without showing why.

A short solid incline continuing as a dashed slope down to a large dark block. a c b
FIG. 16a, the first step, actually proposed. c, the joints asserted rather than shown. b, the end result, treated as certain.

Illustrative example

"If we let students redo one exam, soon nobody will ever have to pass anything."

A slippery slope argument treats a modest first step as if it automatically triggers a chain of worse and worse consequences, without showing any actual mechanism connecting them.

Some slopes are real: a policy can genuinely set a precedent. The fallacy is claiming the slide is inevitable without evidence that each step actually follows from the last.

Ask what specifically stops the process at step two. If there’s a real answer (a rule, a review, a limit), the “inevitable” slide isn’t inevitable.

Seen in the wild

Real, sourced instances of this technique in actual public debate.

Examples are chosen for how clearly they show the technique, not for who said it.

Donald Trump

Leans right

President of the United States

“So this week it's Robert E. Lee. I noticed that Stonewall Jackson is coming down. I wonder, is it George Washington next week?”

August 15, 2017 (Trump Tower press availability, New York)Official White House transcript archive of the remarks (opens on the source site)

WatchC-SPAN footage of the press conference (opens on the site hosting the footage)
Context
Answering reporters at Trump Tower three days after the Unite the Right rally in Charlottesville, on the removal of Confederate monuments. Later in the same exchange he asked the same of Thomas Jefferson, on the grounds that he too owned slaves.
Reading
Each step is presented as following from the last with nothing to stop it, but no mechanism is offered for why it would. The stated reason for removing the Confederate statues was that those men took up arms against the United States to preserve slavery, which is a line Washington and Jefferson do not cross. A slippery slope skips the argument about where the line sits by asserting there is no line.

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