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[scourge728]

If you'd allow me to continue the derail, I just realized a subreddit that contains all subreddits but itself is just reddit itself

[Dunamisdeos]

If you'd allow me to continue the derail, I just realized a subreddit that contains all subreddits but itself is just reddit itself

[Naturegirl1999]

So reddit carries a reddit inside itself now, great use of placement

[Reelya]

It's from a Bertrand Russell thought experiment in Set Theory.
https://en.wikipedia.org/wiki/Russell%27s_paradox

A set can contain other sets (a set of sets). A set can even contain itself as a member. So, you can divide sets into two types: sets that contain themselves, and sets that don't contain themselves.

You can define a "set of all sets that contain themselves", and all other sets must logically be in the "The set of all sets that don't contain themselves".

However now we have a contradiction. Which type of set is "The set of all sets that don't contain themselves"? If it doesn't contain itself then it belongs in "The set of all sets that don't contain themselves" meaning it must contain itself, meaning it can't contain itself and so on.

The Barber Paradox was actually used by Russell as a example of the Paradox in regular language:
https://en.wikipedia.org/wiki/Barber_paradox

The barber is the "one who shaves all those, and those only, who do not shave themselves". The question is, does the barber shave himself?

[Naturegirl1999]

Ah yes, human language paradoxes, there is a heap paradox too. A grain of sand cannot be a heap, adding a single grain of sand does not make it a heap. When does it become a heap?

[Egan_BW]

When it looks like a heap.

[Eric Blank]

When someone walks into the room and asks why theres heap of sand on the floor

[Naturegirl1999]

How many grains of sand makes it a heap? What is the largest non heap amount of grains? That is why it is a paradox because adding a single grain does not make a heap

[Egan_BW]

A heap is a shape, not a number.

[Naturegirl1999]

I read it wrong. Removing a grain from a heap doesn’t make it a non heap. It is called the Sontes paradox.

[Reelya]

That's Sorites not Sontes.

But if you check the source you can formulate it for addition or subtraction, both forms exist.

[scriver]

It's from a Bertrand Russell thought experiment in Set Theory.
https://en.wikipedia.org/wiki/Russell%27s_paradox

A set can contain other sets (a set of sets). A set can even contain itself as a member. So, you can divide sets into two types: sets that contain themselves, and sets that don't contain themselves.

You can define a "set of all sets that contain themselves", and all other sets must logically be in the "The set of all sets that don't contain themselves".

However now we have a contradiction. Which type of set is "The set of all sets that don't contain themselves"? If it doesn't contain itself then it belongs in "The set of all sets that don't contain themselves" meaning it must contain itself, meaning it can't contain itself and so on.

The Barber Paradox was actually used by Russell as a example of the Paradox in regular language:
https://en.wikipedia.org/wiki/Barber_paradox

The barber is the "one who shaves all those, and those only, who do not shave themselves". The question is, does the barber shave himself?

Yes, but that doesn't make him not a barber. The definition of barber is not "one who shaves all those, and those only, who do not shave themselves", it's "one who shaves people as an occupation or have the skillset as such" (and/or also cuts hair in English, I guess). Even if you shave yourself, your occupation remains the same. This isn't a paradox, it's deliberately thinking dumb in order to create a paradox where there is none.

Besides, everybody knows barbers don't cut their own hair.

[Reelya]

You just changed the definition, and showed that your own definition doesn't have a paradox. That's not a legitimate way to solve logic puzzles. It's still a paradox according to the definition given.

[scriver]

But that isn't the definition to anyone. If you've got to invent a whole definition in order to have your paradox, it isn't a paradox, you're just trying too hard.

[Arx]

The paradox isn't actually about barbers, and the barber version is generally considered to have an obvious answer. The point is to be an example.