202110231517 Self-reference

In language, self-reference is any sort of statement that refers to itself or its own referent. For example "This sentence is not seven words long" is a sentence that refers to itself. Other things can be self-referential if they contain copies of themselves within themselves, such as images.¹

Perhaps more interesting is the philosophical and intellectual forms of self-reference and the paradoxes that can arise from them. Many of these types of paradoxes are semantic, set-theoretic, or epistemic in nature.

Here are some examples:

• Is it possible for an omnipotent being to create an object that it could not lift?
• "This sentence is true."
• Gödel's incompleteness theorem and the halting problem.

Self reference

The ancient Ouroboros is a snake or dragon that continually eats its own tail in a circle, symbolizing self-reference.