The Liar Paradox Is A Self-Referential Conundrum
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The liar paradox, also known as the liar sentence, states "this sentence is false." If that statement makes you go a little crazy, you're not the first one. The liar paradox first came about in ancient Greece, and philosophers have been puzzling over it ever since. It's even said that the gravestone of scholar Philetas of Cos, from the third century B.C.E., is engraved with the words "'Twas the Liar who made me die, And the bad nights caused thereby."
The Paradox Of The Heap Asks "When Is A Heap Of Sand No Longer A Heap?"
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When is a heap not a heap? No, this is isn't a trick question, or the setup to a lame joke. This question is at the crux of the paradox of the heap, which is also known as the sorites paradox. The paradox goes something like this: Imagine a heap of sand. Take away one grain of sand, and you'd probably still call it a heap. Keep taking away one grain of sand at a time. At what point is it no longer a heap? What is a heap anyway?! We don't even know anymore...
The Ravens Paradox Is A Confusing Philosophical Conundrum
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The following story is about a raven and an apple. It seems quite simple and easy to follow, but it only gets more complicated from here. In this story, the apple is green, and the raven is black. Because this apple is green, we can conclude that all ravens are black. Where did we lose you? This is the paradox of the raven, a philosophical paradox that looks at how conclusions can be confirmed by positive instances. Let's try it again, slower this time...
Can The Unexpected Hanging Paradox Ever Be Solved?
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The unexpected hanging paradox poses a famous problem that has yet to be resolved. Despite significant interest from several schools of thought, no final resolution has been established. The paradox goes like this: There is a prisoner waiting to be executed. The guards tell the prisoner he will be hanged at noon on a weekday, but they don't tell him exactly when, just that he'll be surprised on the morning of the execution. The prisoner rules out Friday as a potential day of his execution, because if he were alive at noon on Thursday, a Friday execution wouldn't come as a surprise. And since he can't be hanged on Friday, the prisoner rules out Thursday, because if he were alive at noon on Wednesday, a Thursday execution wouldn't be a surprise, either. By this same logic, the prisoner rules out all of the other days of the week. Yet, when the prisoner was executed on Wednesday, he was completely surprised. Where was the flaw in the prisoner's logic? This paradox has been called a significant problem for philosophy.
Does The Grandfather Paradox Prove Time Travel Is Impossible?
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As far as we know, time only travels forward. The grandfather paradox is a thought exercise that some argue suggests time travel is impossible, while others argue it suggests multiverses exist. The paradox asks what would happen if you traveled back in time and killed your grandfather when he was a child. If your grandfather died young enough, he wouldn't have been able to father your parent, thus you would not be alive. But if you weren't alive, you wouldn't be able to travel back in time to kill him, so he would be alive. And so on... The simplest solution to this paradox is that when you go back in time, you're not going back in time in your own history, but rather a copy of your history. Then, your actions don't influence future events in the that timeline you started with.
Key Facts to Know
What if you traveled back in time and killed your grandfather when he was a child? This is the grandfather paradox. 0:07
Quantum superposition is what makes the strange result of the double slit experiment possible. 1:11
Some schools of thought regarding the grandfather paradox maintain that the paradox suggests time loops and time travel into the past are impossible. 1:54