Tagged Questions

Questions pertaining to logical constructs

learn more… | top users | synonyms

0
votes
1answer
1k views

Meaning of “either”: “not /A or B/” = “not /either A or B/”?

In a positive sentence, "either . . .or" is sometimes used to express an exclusive disjunction. However, what happens when “either” is used in negation, as in sentence two below? Is the meaning the ...
19
votes
7answers
10k views

“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 ...
4
votes
2answers
481 views

What's the difference between “Not Completely True” and “Completely Not True”?

From what I understand, in second order propositional logic, ∀¬x and ¬∀x are equivalent statements. Apparently these are not equal. ¬∀x ≡ ∃¬x However, rendered into the English language, consider ...
2
votes
2answers
205 views

And/or in total negation: “Some people are not able to interpret and/or analyze”

In the following sentence, the “and/or” seems odd in a case of total negation: Evidently some people are not able to interpret and/or analyze at that deeper level. Because the sentence says “are not ...
1
vote
2answers
116 views

Without, free from, lacking, etc.: Unambiguous total negation with “OR”?

In the following, “does not cause” seems to be clear negation, and total negation requires “or”, therefore: The widget does not cause deformities or cracks However, it is unclear to me whether ...
4
votes
2answers
868 views

Does the plural include the singular?

Does the plural include the singular? And if so, in what sort of cases? This question has arisen because of the example sentence below. Amendment shall be permitted only in cases of: 1. deletion ...
6
votes
1answer
184 views

Historical frequency of expression “and/or”: Corpus search

What is the historical frequency of the expression “and/or”? I have a feeling that I almost never see it in older texts, but that it is has become exponentially common in the past five or ten years. ...
-2
votes
2answers
113 views

No possibilities are ruled out

Suppose that two binary (yes-no) qualities are being considered. Often (yes, actually!) I want to express that all four combinations are possible: yes-yes, yes-no, no-yes, no-no. Is there a concise ...
2
votes
2answers
415 views

Unambiguous Way of Stating a Biconditional in Plain English

I am having a hard time understanding this section in Wikipedia's article on Logical biconditionals: Colloquial usage One unambiguous way of stating a biconditional in plain English is of the ...
0
votes
2answers
444 views

Double negations [duplicate]

Possible Duplicate: Is there a rule about double negations that aren't meant as double negations (e.g. “We don't need no education”)? Meaning of “you don't need no memory” and ...
0
votes
3answers
773 views

What is the opposite of modal?

Is there a word for the opposite of modal? Particularly, is there a word for the opposite of modal in the logical sense of relating to the modality between propositions? In other words, is there a ...
2
votes
3answers
2k views

What does “an A/B metaphor” mean?

I wonder what "an A/B metaphor" means, for example, in the following quote from Wikipedia about formal language: "In some applications, especially in logic, the alphabet is also known as the ...
1
vote
3answers
171 views

Can I express future action without the exclusion of former activity?

Consider the following scenario. Someone is hired for a job and is new to the career field. For instance, a new accountant. After being an accountant for a very short period of time, and doing an ...
4
votes
2answers
291 views

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?
0
votes
2answers
503 views

All X are Y. Then Some Y is X? [closed]

I have the following statement: All the actors are girls. All the girls are beautiful. The conclusions are given below: Conclusions: 1)All the actors are beautiful. 2)Some girls are actors. My ...
4
votes
5answers
2k views

The size of my confusion is “second to none”

Why "second to none" is being considered as "the best" instead of "the worst" (almost non existent)? To my understanding - "none" is "nonexistent", while "second to none" should be... well... almost ...
6
votes
5answers
2k views

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 ...
1
vote
2answers
402 views

Improper usage of “subsequently” in the latest Futurama episode?

In the latest Futurama episode, called Cold Warriors, the professor says the following: The common cold died out 500 years ago and subsequently humanity lost all resistance to its ravages. ...
7
votes
1answer
3k views

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" ...
5
votes
2answers
548 views

“There is no doubt this is arguably wrong”

This is from a review of something: There is no doubt that the (product name) is arguably the best consumer (product category name) currently on the market. I stopped for a while after reading ...
10
votes
5answers
12k views

“If” vs “Only if” vs “If and only if”

If I said: Yell only if I fall. Would the person have to yell once I fell? Sources of confusion Wikipedia This guy
4
votes
3answers
1k views

'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 ...
10
votes
7answers
3k views

Does 'some' necessarily imply 'not all'?

If some X's are Y's, does that imply that some X's are not Y's?
5
votes
6answers
778 views

Is there a common English phrase for the 'so absurd it must be true' logical fallacy?

There are various common (often Latin) phrases for various logic fallacies, such as post hoc ergo propter hoc, argumentum ad populum, slippery slope fallacy, etc. Is there a common phrase used to ...
3
votes
2answers
1k views

Usage of “if and only if” as a nontechnical term

The phrase "if and only if" (iff) is commonly used in the field of mathematics (⇔) and computer programming, as a conditional expression in classical (Boolean) logic. Within that scope, it might not ...
7
votes
5answers
535 views

Does this logical fallacy have a name?

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 ...
14
votes
5answers
10k views

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 ...
9
votes
5answers
52k views

“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?
6
votes
6answers
845 views

The word 'not' often doesn't mean total negation in mathematical sense?

Consider the following conversations: X1: I paid $10 for that hamburger. Y1: That's not cheap! X2: I pay $1 for broadband Internet access. Y2: That's cheap! X3: I paid $1 for a hot ...
4
votes
2answers
307 views

Is it true that

Is the following sentence grammatically incorrect? Is it true that 1+1=2 ? I know it is easier to say: Is 1+1=2 true?