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40

No, strictly, they do not convey the same meaning. In practice, your second sentence is often used to mean the first. I believe x does not equal y means that you actually hold a belief about the inequality of x and y. I don't believe that x equals y simply means that a belief about the equality exists, but you do not share that belief. If you substitute ...


18

Recall that in formal logic, your expressions are used as follows: A if B means that B implies A. A only if B means that A implies B A if and only if B means that A is equivalent to B. For example if in the morning I tell my wife "I'll buy that shirt we saw yesterday only if it costs less than 40 dollars" and she sees me wear it in the evening, she can ...


17

"Either A or B" most precisely means, in symbolic logic terms, "A XOR B", where XOR is the "exclusive or". So yes, it means "A or B but not both". It isn't always actually used with full precision, though, so, as usual, context has to be taken into account. If somebody says, "select either A or B", for example, they definitely mean that you should not ...


16

This is bordering on logic rather than language, but the answer is definitely no: Some is "an indeterminate amount", which means it can be all. If I say I have some red M&Ms in my bag, it could be that all of them are red. But then, depending on inflection, as @codelegant pointed out, I could be using emphasis on some to indicate that not all are ...


16

Languages are not formal logic systems, and words do not derive their meanings from the definitions in dictionaries. If they did, then your argument would mean something, but as it is what you have is an amusing but pointless exercise. Words derive their meanings from their shared usage in a linguistic community, and those meanings are ultimately grounded ...


15

This is the Cooperative Principle in action: (link to comic) If you have no particular reason to think I will buy you a wallet and I say: I will buy you a new wallet if you need one. then, under the Cooperative Principle, you can safely assume that this is all you want / need to know. But if there were other conditions in which I'd buy you a wallet, ...


15

The original was actually Shakespeare: all that glisters is not gold, but that needn't concern us here. OP has simply misparsed the sentence - it actually means "Not everything that is gold glitters" (which is to say, "There are some things which are gold that don't glitter"). You can always Google "every x is not y" for more discussion of why this type of ...


15

One relevant term from logic: red herring — The idiom "red herring" is used to refer to something that misleads or distracts from the relevant or important issue. Specific forms of red herring exist and I find that appeal to motive fits nicely: appeal to motive — Appeal to motive is a pattern of argument which consists in challenging a ...


14

You're correct, it is indeed contradictory. Taken purely logically, then if neither can live while the other survives, then if Harry is alive Voldemort must be dead and if Voldemort is alive Harry must be dead. Since we know both Harry and Voldemort are alive, the statement is clearly false. Since the statement is part of a piece that refers to them as ...


13

To be second to none means that nobody is ahead of you. None is nonexistent, which means that someone nonexistent is ahead of you--nothing better exists so you are the best.


13

I would say those are near-tautologies, and certainly truisms.


12

Shakespeare's line is the best known example of this general phenomenon where a universal quantifier scoping over negation gives a counterintuitive meaning. The expected meaning of: All that glisters is not gold. Would be: For each thing that glisters, it is not gold. Instead, the meaning to be understood is: Not everything that glisters is ...


11

No; the sentence "Is it true that 1 + 1 = 2?" is perfectly grammatically correct. In logic, there are tests that depend on being able to prefix almost arbitrary sentences with "It is the case that ..." or "It is true that ..." and if the result still makes sense, then certain properties hold (it is a declarative sentence which could be a proposition). For ...


11

Fairly obviously there can be multiple X's, any or all of which may be 'arguably' the best X. To qualify for that designation they only have to be capable of being argued for – they don't need to actually be the best. Equally obviously there may be some X's which are so bad they're not remotely capable of being considered for 'best', and some other X's that ...


10

Quoting the Wiktionary usage notes for center: Merriam-Webster's Collegiate Dictionary observes that center around is objected to by some people on the grounds that it is illogical, but states that it is an idiom, and thus that such objections are irrelevant. It offers revolve around as an alternative to center around for those who would avoid the idiom. ...


10

You're correct: subsequently doesn't imply causation. subsequent: Following in order or succession; coming or placed after, esp. immediately after. consequent: Following as an effect or result; resulting. (Both definitions are from the Oxford English Dictionary.) You might use subsequently to avoid the post hoc, ergo propter hoc fallacy.


10

You might consider this as a case of ignoratio elenchi, where an irrelevant argument is presented as an answer to the question at hand: Ignoratio elenchi, also known as irrelevant conclusion, is the informal fallacy of presenting an argument that may or may not be logically valid, but fails nonetheless to address the issue in question. [...] ...


9

To get the logical negation of "must", switch must with a different verb. A: We must study English grammar. B: No, we need not study English grammar. or B: No, we don't need to study English grammar. or B: No, we don't have to study English grammar. or B: No, we are not required to study English grammar.


9

Axiomatic is another fine choice here. It means self-evident and beyond requiring proof. Link to dictionary definition.


7

No, therefore should not be reserved for conclusions beyond a reasonable doubt. It is merely a transition similar to thus or as such: Therefore, I ordered pepperoni. Thus, I ordered pepperoni. As such, I ordered pepperoni. The extended conversation could have been: I like meat on my pizza. Therefore, I ordered pepperoni. You can test ...


7

Yes. If I offered you some peanut M & M's, I would feel that you misunderstood me if you took them all. :)


7

The biggest problem in finding a technical fallacy is that "absurd", in this context, isn't detailed enough. Why is it absurd? The idea that any absurd thing could be believed if it was simply absurd enough is not really true. The idea of arguing something as true because no one would make it up is close to these fallacies: appeal to authority — ...


7

"Consequently" contains information about causality and "subsequently" does not, but that doesn't mean "subsequently" is improper. Did B (humanity lost its resistance to the common cold) happen after A (the common cold died out)? Yes? Then of course B happened subsequently to A. While "consequently" means that A caused B, the presence of "subsequently" ...


7

It means not everything that is gold glitters. Tolkien undoubtedly was borrowing from Shakespeare here, specifically the poem that one of Portia's suitors discovers when he reads the scroll associated with the golden chest that he has (to his loss) chosen: “All that glisters is not gold— Often have you heard that told. Many a man his life hath sold ...


7

You are correct; Karan of the superuser question you referenced made a grammatical error. It should have been as you phrased it: Not everything in DOS is plain-text That being said, your understanding in the two examples you posted is slightly off. It should be Every human is not a man. There is no human being who is a man. Not every human is ...


7

<statement type="highly opinionated"> I don't think any human language is well-suited to "natural language programming". I don't think there is any such thing in real life. Computer people are always saying, "Wouldn't it be great if instead of having to learn all these complex commands, you could just tell the computer what you want in ordinary ...


7

A circular argument is one where the conclusion is also one of the premises: Good websites are the ones that are effectively designed. In other words, in premise / conclusion form: If a website is effectively designed, then it is good. This is essentially defining good to be equivalent of effective, therefore the conclusion is the premise. ...


7

I consider the use in English to be ambiguous enough in the minds of the average reader that alternative meanings must be considered and analysed, and the following enumerates those meanings and reasons about them... I believe x does not equal y This is ambiguous, as - using symbolic notation to help show the difference - it may mean x != y or !(x = ...


6

TV tropes calls it Hitler ate sugar. It also says it's called "The Association Fallacy".



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