Questions pertaining to logical constructs

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38
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9answers
5k views

“Childlessness is hereditary in our family” What do you call a statement containing a contradiction such as the example?

This kind of sentence is usually absurd and may or may not be recognized as such by the person who utters it. She will regret it till the day she dies, if she lives that long! "Aren't you going to ...
21
votes
10answers
4k views

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
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 ...
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 ...
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?
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
9
votes
7answers
971 views

Word or term for an argument that is inherently true

What do you call an argument/position that is impossible to counter because it depends on undefined adjectives/adverbs? Examples: Good websites are the ones that are effectively designed. ...
9
votes
5answers
53k 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?
8
votes
8answers
3k views

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 ...
8
votes
5answers
6k views

“Neither can live while the other survives”— does it make logical sense?

At the end of the fifth book of Harry Potter, "The Order of Phoenix", there is a prophecy concerning Harry Potter and Lord Voldemort: The one with the power to vanquish the Dark Lord ( Lord ...
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 ...
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" ...
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 ...
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 ...
6
votes
3answers
272 views

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 ...
6
votes
1answer
185 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. ...
6
votes
2answers
308 views

Would the rejection of an argument because of a grammatical error be a type of logical fallacy?

Many people may have experienced situations (often online) where someone dismisses another's argument not on the merits of the argument, but because of a grammatical (or, more generally, mechanical) ...
5
votes
2answers
549 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 ...
5
votes
6answers
780 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 ...
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 ...
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 ...
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?
4
votes
2answers
870 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 ...
4
votes
2answers
292 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?
4
votes
4answers
687 views

What's the logical fallacy where people dismiss what you say as irrelevant to the real-world?

Quite often I see derision about ideas by people who label them as 'too academic'. Often this appears to result from laziness or an unwillingness to stretch their thinking. What's the logical ...
4
votes
2answers
483 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 ...
4
votes
2answers
773 views

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 ...
4
votes
2answers
307 views

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.
4
votes
2answers
194 views

At least two or more: Not always redundant?

At least two or more Is the “or more” bit above ever not redundant? Seems absolutely redundant to me, but it gets about 170 million Google hits, and many from government sites and university ...
3
votes
4answers
129 views

What is the name of the “agency” fallacy?

I'm looking for the name of the logical fallacy where intent or agency is assumed when in fact there is none. It's a common fallacy in my experience, but I can't seem to find it described ...
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 ...
3
votes
4answers
516 views

A word for when two statements are both true or both false

Is there a word which basically means that there are two statements that are both true, or both false, but not one true and one false? In computing, we call this a bitwise and. 3 * 3 = 9 4 * 4 = 16 ...
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 ...
2
votes
3answers
237 views

Is English particularly well suited for so-called “natural language programming”?

Programming languages like sEnglish, Inform7, WolframAlpha, and even AppleScript purport to use the "natural language programming" (NLP) paradigm. Even SQL is a kind of NLP, if you think about it. ...
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 ...
2
votes
4answers
239 views

Justifying one wrong thing by comparing it its opposite which is also wrong

Is there a word or name for the phenomenon or syndrome in which people try to defend one wrong thing by comparing it something that is total opposite of it but also wrong? For example: Drone ...
2
votes
2answers
206 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 ...
2
votes
3answers
151 views

Name for logical fallacy of “implied guilt”?

For example; "No puppies were harmed in the making of this soda", implying that puppies are generally harmed in the production of soda, and thus casting the competition in a bad light. Is there a ...
1
vote
3answers
413 views

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' ...
1
vote
2answers
403 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. ...
1
vote
1answer
119 views

What does “Graduates from business school or Economics with mathematical background” mean?

Hello I have a question about "English logic". For instance on a job offer I see this requirement: Graduates from business school or economics with mathematical background. So If I ...
1
vote
4answers
114 views

What is the verb form of “conjunction” in the logical sense?

In logic and computer programming, a conjunction of two logical statements is said to be true if and only if both statements are themselves true. For instance: "The sky is blue" and "the grass is ...
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 ...
1
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1answer
128 views

Why is there no word for and/or? [closed]

It seems like it would be really useful to have a single word like "anor" instead of the clunky "and/or" construction that people use. After all, "or" by itself is usually used to mean "exclusive or" ...
1
vote
2answers
130 views

What is the difference between “It is raining” and “'It is raining' is true?” [closed]

"It is raining." "'It is raining' is true." Does "is true" make any difference? Thanks. This link gives context to this question and testify that I'm not a nut (yet).
1
vote
1answer
46 views

Some + Countable Noun: True Only When Plural?

Assume there are multiple books on a shelf. At least one book is red. At least one book is blue. Sentence in dispute: Some of the books are red. Is this sentence false if only one book is red? ...
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2answers
107 views

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 ...
1
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1answer
112 views

What do you call this (these) writing “fallacies”

I just read this answer on Chinses.Stackexchange, and I see some obvious logical "leaps of faith" that I would like to know their most accurate and concise labels. Many thought it is difficult to ...
1
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1answer
267 views

(GRE) Parallel Structures

The following is a sample question taken from the revised version of the ETS-administered Graduate Record Examination (GRE). I normally try hard to understand the logic behind selecting the choices ...
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 ...