Paradoxes

Paradoxes are impossible situations which are possible.

Logical paradoxes

Tortoise versus Achilles

If a tortoise is racing Achilles and you give the tortoise a head start, Achilles will never beat the tortoise since in the time Achilles has closed up the distance to where the tortoise was at the head start, the tortoise has moved further and so on.

Catch-22

To be in the need of something that you can only have if you don't need it.

Barber paradox

If a barber only shaves men who do not shave themselves, will the barber shave himself?

Liar paradox

I can't say I'm lying.

Curry's paradox

If this sentence is true then Santa Claus exists.

Opposite day

Opposite day is opposite of itself.

Ship of Theseus

If a plank of a ship is replaced, it is still the same ship. If you replace all the planks one by one, it's still the same ship. If you use the old planks to build the ship, it's still the same ship.

Sorites paradox

A grain of sand doesn't make a difference between a pile of sand or not. If you have a grain of sand, which is certainly not a pile, and one by one add a grains of sand until it has a million grains, it still isn't a pile.

Philosophy

Fitch's paradox

If all truth is knowable, then all truth must me known.

Socrates paradox

I know only that I know nothing.

Omnipotence paradox

Omnipotent means able to do anything so is an omnipotent being able to make a rock to heavy for itself to lift?

I also made up one

Logic is an assumption. The explanation is that when you leave a room with table in it how can you be sure that it doesn't fly out of the house and come back without anyone noticing when you go back into the room. So if logic is an assumption it might not be true, so how can we be sure that one plus one equals 2?