When is a Circle not a Circle?

The Committee of Conundrums is proud to present this treatise on the paradox of the circle.

It's a shape, but is it a shape? Or is it a... Pizza Pie in disguise?

Read on for more mind-bending examples of circular reasoning, including:

• The Paradox of the Umbrella
• The Paradox of the Toaster
• The Paradox of the Squircle

Don't try this at home, folks.