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Questions tagged [logic]

Questions pertaining to logical constructs

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34 votes
9 answers

Does "either A or B " preclude "both A and B"?

In mathematics, "A or B" includes "A and B". Does "either" mean "A or B but not (A and B)" or does it include the possibility of "A and B"? The context might be mathematics, formal logic or ordinary ...
Bogdan Lataianu's user avatar
23 votes
8 answers

"All that is gold does not glitter"

"All that is gold does not glitter" is the first line of a poem from the Lord of the Rings and it's supposed to mean "not all gold glitters" but I'm struggling to see how this can be deduced. If all ...
RobertRW's user avatar
  • 349
7 votes
4 answers

Ambiguity in Negation: "John did not come because of the rain"

John did not come because of the rain. This sentence seems to allow the following two completely different interpretations. John did not come. And the reason was the rain. John came. But the reason ...
curious-proofreader's user avatar
21 votes
10 answers

Is "I believe x does not equal y" the same as "I don't believe x equals y"

Given x and y could be any phrase, do these phrases always mean the same thing? If not, what's the difference? I believe x does not equal y I don't believe x equals y
suryanaga's user avatar
  • 313
2 votes
3 answers

How do definitions of words imbue meaning? [closed]

How do definitions of words imbue meaning? To give you a gist of what I try to discover, I'll define a collection of sets of words and show that their intersection contains all 'circular defined' ...
Cuc's user avatar
  • 207
1 vote
1 answer

What's the word for using a general argument that upon inspection does not apply?

Examples, some are ridiculous: Someone refuses to buy a lab grown diamond because 'all diamonds are blood diamonds'. We cannot buy a sports car because 'the trunks of sports cars are too small', even ...
OrigamiEye's user avatar
17 votes
5 answers

"Centered on" or "centered around"

I have often heard presenters talking about something centered around another thing, but it seems a bit illogical and hence improper to talk like this. Am I right about this?
Anglophobia's user avatar
12 votes
10 answers

Understanding the purported ambiguity in “Every boy didn’t run”

I am a com­puter sci­ence pro­fes­sional. I am read­ing the book Nat­u­ral Lan­guage Un­der­stand­ing by James Allen where he writes: “Every boy didn’t run” which is am­bigu­ous be­tween the read­...
user8673's user avatar
  • 223
8 votes
3 answers

Difference between "not every" and "every ... is not"

I've always understood that you can order the words not and every (or similar words) in the following two ways to convey distinct logical meanings. Every human is not a man. There is no human being ...
Overv's user avatar
  • 195
8 votes
5 answers

Does this logical fallacy have a name? [duplicate]

A phrase being used by the "news" media regarding the recent arrest of people in Columbus, NM is "firearms favored by the Mexican cartels", referring to their purchase of AK47s and other ...
jcomeau_ictx's user avatar
7 votes
3 answers

Is there a term for it when you use an obviously false statement to highlight the falsity or absurdity of another?

For example, person A states something. Person B says "And pigs fly" to imply person A was wrong. If there's no term for it, what could you call that that sounds smart?
Boann's user avatar
  • 734
15 votes
6 answers

Term for the "extreme-extension" version of a straw man fallacy?

Take the most obvious, unimpeachable statement imaginable: Drinking water is good for humans. I am looking for a word that describes the action of taking the argument, applying some unreasonable ...
user1717828's user avatar
  • 2,945
14 votes
2 answers

Difference between "subsequently" and "consequently"?

When studying and reading course material in "softer" sciences that are descriptive the word "subsequently" appears in a way like "and subsequently" ...what does it mean, disctinct from "consequently" ...
Niklas Rosencrantz's user avatar
11 votes
4 answers

Does the word "and" always mean a logical (boolean) operation?

For a simple phrase like "macaroni and cheese" it's clear you want both macaroni and cheese, not one or the other. But as more and more words are added, I've noticed a tendency to begin to read "and" ...
Ðаn's user avatar
  • 295
10 votes
8 answers

Word/phrase/idiom to describe avoiding answering a question by stating the question doesn't need to be asked

I run into this situation often in the office. I have a specific question to ask somebody and have chosen the person to ask it, but that person doesn't know the answer. Instead of answering the ...
Sprague's user avatar
  • 203
8 votes
6 answers

Can I say "We don't must", any alternative using a modal verb if I can't?

Let me explain. Suppose someone says "We must play a game now". I disagree, but only on that we have to do it. I shouldn't answer "We must not" because I would be saying that the game is not to be ...
Vinko Vrsalovic's user avatar
7 votes
5 answers

Cut the lights on

This expression is commonly used in the southern United States from Oklahoma to Virginia, and is patently illogical, and yet fails to inspire any consternation or lack of semantic connection. On a ...
gtshin's user avatar
  • 79
6 votes
4 answers

Overuse of "however" in my scientific writing? [closed]

In scientific writing, I always feel the need to logically connect all my sentences to have a clear logical path between beginning and end of a paragraph, else it is just feels like a list of random ...
Konrad Höffner's user avatar
6 votes
2 answers

Hypernym for "conjunction" and "disjunction"

Is there a hypernym for conjunction and disjunction, in their logical senses? Just using "junction" doesn't seem right to me.
Xophmeister's user avatar
5 votes
4 answers

Use of "and" and "or" in lists when intent is to dissallow all items

Sometimes it is unclear to me whether "or" or "and" should be used in a list. For example I have seen the following lease agreement: The dwelling may not be used for illegal activities: including ...
Celeritas's user avatar
  • 2,878
4 votes
2 answers

What fallacy is this? "Your argument is wrong/invalid because it's just an opinion."

I encounter this fallacy frequently in online discussions where an opponent completely disregards all of my premises and says my conclusion is invalid because it's an "opinion" and "not objective." ...
Cyrad's user avatar
  • 143
4 votes
3 answers

'Therefore' in an illogical logic sense

I have a co-worker that is always saying "Therefore, A B C" when the "A B C" isn't a conclusion from any sort of deductive reasoning. For example, Me: ... thus, that's how it works. Her: I think ...
OghmaOsiris's user avatar
  • 1,085
3 votes
3 answers

How to succinctly and clearly connote the reverse of a statement

Here's a published example of a problem I come across frequently: A cop is six times more likely to be shot by someone black than the opposite. Let us assume that the writer meant to say: ...
feetwet's user avatar
  • 1,320
3 votes
1 answer

Is there a contraction for non-exclusive or?

I find that often, in technical writing, I want to specify that or is non-exclusive: or ≠ xor; or = and/or. (Stylistically, "and or" is terrible and gets tiresome quickly;) As an example of the type ...
DukeZhou's user avatar
  • 1,163
2 votes
1 answer

“Periodically” – How to Use This?

So, I happen to be in the process of creating this research paper about a historic figure; I had used Google to search for a synonym of occasionally, and one of the words I stumbled across was “...
Kit's user avatar
  • 107
2 votes
1 answer

What is the difference between these two sentences? "If A is true, then B is true" and "Since A is true, B is true"

Consider the following two sentences: If A is true, then we can conclude that B is true. Since A is true, we can conclude that B is true. I have two questions: What is the difference ...
iwbtrs's user avatar
  • 159
2 votes
5 answers

Short human descriptions for logic's AND, OR and NOT

In a user interface, we are offering the user to combine searches using either AND, OR or NOT We have little ...
commonpike's user avatar
1 vote
1 answer

Word that serves the purpose of "xor?" [closed]

In programming we have the term "xor gate" for when one of two things is allowed, but not both. That is, P XOR Q is true if and only if exactly one of them is true, false otherwise. But English is ...
Aayla Pozho's user avatar
1 vote
4 answers

What English construction matches the Boolean condition of nand?

English language usage has some logical word pairs including: Or | Nor Either | Neither With | Without But there doesn't seem to be an opposition to the word "and". In computer engineering and ...
Blubberguy22's user avatar
1 vote
4 answers

"As a [noun]" followed by mismatching subject

There is one particularly commonly used language construct that I find logically incorrect. However, as a non-native English speaker, I can't decide authoritatively on whether the usage is actually ...
rhino's user avatar
  • 113
0 votes
5 answers

Is there a difference between "being selected" and "being pre-selected"?

I am reviewing a document where it is stated that something is part of a set of pre-selected items. To me that doesn't make sense. Isn't everything selected also pre-selected by definition? I mean ...
Andra's user avatar
  • 790
-1 votes
10 answers

Boolean OR in English

What is the English equivalent of boolean-OR, which conveys the meaning of "either of the options or both", as opposed to XOR, which conveys the meaning of "strictly one or the other"? "Either or ...
TruthOf42's user avatar
  • 285