Follow your curiosity

What discovery has been shared with you?

FACTREE gives you something interesting to discover every day — and something worth talking about together.

Start with one fact. Explore it, go deeper, then follow whichever branch catches your imagination.

Choose subjects for a surprise

Exploring any topic

Begin your discovery

Your next discovery is one click away.

Choose one or more subjects above, or leave Any Topic selected and let curiosity decide.

Philosophy

The Nature of Necessity and the Essentialism Debate

Quick fact

The essentialist debate over necessity was famously shaped by Saul Kripke, who argued that 'Water is H2O' is a necessary truth discovered by science, not a truth of logic—a claim that challenges the old idea that all necessary truths are known a priori.

Why this is interesting

You know that 2+2=4 and that water is H2O. But why are these truths not just true, but necessarily true—and what makes them so?