Socrates famously once said: "I know one thing, that I know nothing." This crucial piece of insight, from one of the founders of Western philosophy, basically means that you should question everything you think you know. And if you take a truly closer look at things, you'll start to recognize paradoxes all around you. These paradoxes stimulate a great deal of philosophical thinking, and many have been able to both summarize and expose fallacies of important philosophical problems.
With some dating back to ancient times, click on for some of the most influential philosophical puzzles and paradoxes ever conceived of.