Definition:Equivocation

Definition

An equivocation is a shift in meaning of an ambiguous term.

If an argument's persuasive force depends on utilizing an equivocation it is fallacious.

To make such an argument is to commit the fallacy of equivocation.

Examples

Smullyan's Equivocation

Some cars rattle.

My car is some car.

Therefore, my car rattles.

Equivocation of Nothing

The classic often-cited argument is:

Candlelight is brighter than nothing.

Nothing is brighter than the light from the sun.

Therefore, candlelight is brighter than the light from the sun.

This version is given in 1982: P.M. Cohn: Algebra Volume 1 (2nd ed.):

Any soap is better than no soap.

No soap is better than Wonder-Bubble.

Therefore, any soap is better than Wonder-Bubble.

This version is given in 2008: David Joyner: Adventures in Group Theory (2nd ed.):

Time waits for no man.

No man is an island.

Therefore, time waits for an island.

Sources

• 1995: Merrilee H. Salmon: Introduction to Logic and Critical Thinking: $\S 2.2$