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2+2 = not what you think

felipec.substack.com

Changing someone's mind is very difficult, that's why I like puzzles most people get wrong: to try to open their mind. Challenging the claim that 2+2 is unequivocally 4 is one of my favorites to get people to reconsider what they think is true with 100% certainty.

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This is usually covered in basic math courses or textbooks. For example, freely translated from The Open University of Israel's a quick intro to logic:

We mentioned that 3*4 > 10 is a true statement. This statement is false if the numbers are actually written in Hexadecimal base, where "10" represents the decimal number 16.

So that we don't require the assistance of a lawyer every time we determine a statement to be true or false, we agree that in every case where concepts have a common interpretation or context, we assume (without mentioning) that we speak in that common context, [...]

My post has absolutely nothing to do with bases. Did you read it?

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My comment has nothing to do with bases either. It has everything to do with assuming common context.

This is like you replying “My post has nothing to do with 3*4”, you’ve missed the point entirely and got hung up on the example.

This is your claim:

This is usually covered in basic math courses or textbooks.

What is "this" in this context?

Also, you claimed that "this" is taught in basic math textbooks, but you din't provide an example of such textbook, you provided one of logic.

“This” is that we assume the common interpretation if one exists. The second quoted paragraph explains it.

Logic is a part of math. The book is from an undergrad discrete math course I took once, so I pulled the book from the shelf to quote for you.

“This” is that we assume the common interpretation if one exists. The second quoted paragraph explains it.

Which is?

Logic is a part of math.

No. Logic and mathematics have a complicated relationship.

The book is from an undergrad discrete math course I took once, so I pulled the book from the shelf to quote for you.

So it wasn't a "basic math" course, and you don't have an example of a "basic math" textbook covering "this".

I’m not sure what your angle here is. What are you trying to say? Do you actually not understand my point, or are you just being obtuse?

Discrete math is as basic as it gets, it’s first semester CS/Electrical/Math/Physics. It’s literally the base. Saying logic isn’t part of math but has “a complicated relationship” with math… again, I don’t see what you’re getting at. Seems like an objection for objection’s sake.

Again, the point is that it is convention to assume the common interpretation/ context of a statement when we assess its truth value, unless otherwise specified.

Discrete math is as basic as it gets, it’s first semester CS/Electrical/Math/Physics.

Of university. You were taught math before that, weren't you?

It's not "basic math".

Saying logic isn’t part of math but has “a complicated relationship” with math… again, I don’t see what you’re getting at.

That your statement is not quite correct.

Again, the point is that it is convention to assume the common interpretation/ context of a statement when we assess its truth value

"Convention" literally means usually done, not always.

2+2 is unequivocally 4 unless the numbers are redefined, such as by changing the base you're working in.

Except my post proves that's not the case. Again: I did not change any the base in my post.

You’re missing the point. It’s not that you literally changed the base, but you did effectively the same thing

No. Apples are not oranges. Abstract algebra is a much less known concept than numeral systems. Virtually nobody thinks of that when considering 2+2.