Questions tagged [logic]

For questions about logic, whether it concerns syllogistic logic, mathematical logic or the nature of logic itself.

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170 views

Can something end which never began?

I was thinking that if life is infinite then it has no meaning. But if life began then the meaning of life must be for it to end. The meaning is in the future and since the last thing that will ...
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1answer
620 views

Can a sentence without a truth value be true?

I was doing some very, super, light reading on self reference. It seems to me that the statement nothing that I say is true both: cannot be understood with the T-schema; is self referential. - ...
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520 views

are fundamental questions like “cogito ergo sum” even provable? [closed]

The rationalist descartian position states that everything can be doubted except doubt itself. With the phrase "cogito ergo sum" it claims to establish the existence of one ones existence, if i did ...
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4answers
142 views

Why is the Kochsche Curve and programming so similiar? [closed]

I've question which I'm looking for longer time. The iteration process while a for loop > for statement in function_declaration: is looping over all instances and giving out one statement after ...
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2answers
194 views

How can I be certain I exist? [closed]

The question is simply: How can I be certain I exist? Or anything in this "world" for that matter?
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4answers
3k views

Can the existence of God be proved from mathematics? [closed]

This question of highest importance for everybody could not be answered in MO and will not be answered in Mathematics.SE. I can understand why the set-theorists there dive and attack it like vultures. ...
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3answers
273 views

Is the science Physics allowed to ignore the rules of Philosophy of Science resp. the Scientific Method [closed]

The Scientific Method in Science determines that premises, on which a theory is based, must be experimental verified, when possible. It is however possible that theories of the past are based on ...
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3answers
1k views

Asked to analyse a contradictory quote that I don't agree with [closed]

I'm given a quote If you don't like something, change it. If you can't change it, change your attitude". The statement is to discuss how this idea was developed with respect to the two prescribed ...
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If we know “All A's are B's” then can we say “Some B's are A's”? [closed]

If suppose we know "All A's are B's" then can we say "some B's are A's". I know that "All A's are B's" --> "Some B's are not A's" But can we say "Some B's are not A's" -->"Some B's are A's"
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Sentential Derivation: Derive ~(RvB) from ~R and ~B [closed]

I'm having a difficult time deriving ~(RvB) from ~R and ~B. This would be fairly straight-forward if we were allowed to use the DeMorgan Laws, however my professor is not allowing us to use them for ...
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2answers
4k views

If magic is “fake,” why is science real? [closed]

Consider this: I watch a Harry Potter movie when I am a kid (I did) and, as early as kids, of course, older people tend to teach young kids at some point that motion pictures are "fiction" and not to ...
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3answers
215 views

Do I need to implicitly or explicitly have a value to rationally claim that I 'ought to do something'? [closed]

I use Humes idea about the 'is..ought to gap' (or my spin on it) mainly to make sure I have good reasons for what I do -and what I advise others to do- and to make sure actions are not based purely on ...
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2answers
474 views

Does the law of excluded middle follow the law of excluded middle?

Example is that the word unknown is not unknown so it doesn't define itself. Similarly French is not French, it's in English, and "long" is not long and only 4 letters short. That's by example my ...
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2answers
129 views

Does the Universe make sense? [on hold]

When faced with a paradox, we say: well this can't be because it doesn't make sense. p = "x doesn't make sense" q = "x doesn't exist" The contrapositive preserves validity: p implies q (not q) ...
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1answer
60 views

Analyze the following fallacy: [closed]

In a city council says a councilman: "In a time of crisis, wages are not very high and we see with evil eyes the money that we are going in taxes, the more services, the more taxes we have to pay. So ...
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2answers
540 views

We do everything for pleasure

I have been in debate for a while now with me friend. I come here looking for feedback and possible outlooks to related sources. The question we posed a long time ago is interesting one: why do we ...
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2answers
24 views

How do I prove ~(A & B) therefore ~A V ~B using natural deduction? [duplicate]

Been trying to prove this one for a while now and can't crack it. Assume ¬(A ∧ B) Derive ¬A ∨ ¬B
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81 views

Meaning vs. Significance [closed]

From: Philip Johnson-Laird BA PhD Psychology (UCL), Stuart Professor of Psychology Emeritus at Princeton. (Author isn't a logician.) How We Reason (1st edn 2008). p. 433. [Chapter 1] 9. ...
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1answer
81 views

To pass two time for the same place. Logic question [closed]

Let be the proposition: "To visit two times the same place is forbidden". It is forbidden to visit the same place three times? A says: "No, because it is forbidden to visit the place two times". ...
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84 views

Fitch-style natural deduction

How to prove the following questions? (a) p from assumption ¬(p → q) (b) ¬¬p → p from no assumptions.
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179 views

Logic related to Cantor's argument [closed]

Suppose we construct a choice function that separates R/{0} in the interval (0,1) (viewed in base 2) into two sets A and B each consisting of an arbitrary element chosen from every pair of complements....
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103 views

What makes a great scientific question for and/or against a stupid idea?

While I am taking a walk I have come up with quotes, questions and philosophy to motivate and route myself. I recently discovered/invented a new quote which really can have multiple meaning to it (...
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440 views

The median of infinity [closed]

Would it be logical to assume that 1 is the median of countable infinity since all the whole numbers can also be used as its' denominator?
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3answers
843 views

Can there exist Nothing in Something? [closed]

Is it possible for Nothing to exist in Something ? e.g. if something is the whole set can nothing be an element of it ? If you take Nothing from something something remains. If nothing cannot exist ...
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1answer
70 views

Can a different universe be built with three dimensions? [closed]

Can you theoretically create a universe that will have the same dimensions but will look different? For example, a paper that has a limit, or another similar dimension can it be different?
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105 views

Resolving the divide between logic and emotion, and their presence in causality

I've always questioned the dissension between logic and emotion. Whether it is right to disassociate emotion as this is seemingly logical, or promote the wellness of emotion. I'm, whether wise or ...
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239 views

What is the difference between class and concept?

What is the difference between class and concept? − I am not sure whether, for instance, “chair” is typically a class or rather a concept, or both. I would say that it is only a class, though it is ...
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687 views

What is the absolute ultimate subject (like math, literature, etc)? [closed]

Seems like all subjects are branches of more general subject. Pretty much all sciences seem to find their roots in physics but physics is just math. There are many branches of math but still all just ...
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3answers
120 views

Can two different objects at the same time be the same? [closed]

Can two things be different and yet the same at the same time? For example, a chair (white) does not have one leg and another (black) has all of its legs. As in the question, these two things with ...
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2answers
541 views

How to define a number [closed]

What is the positive real number (say less than one) that is not a rational nor an irrational number? I have encountered a mathematical problem that confused me about the definition of real numbers,...
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3answers
779 views

At which point is an insult no longer ad hominem?

During an argument with some people, I come to the conclusion that they are either stupid, ignorant or liars. Let's imagine that we have 2 guys discussing what color they should be painting a room. ...
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1answer
118 views

Are fewer fallacies better than more? [closed]

In case you haven't already figured it out, I like to ask questions about how to measure soundness. Question a Suppose I haven two arguments, X and Y, each consisting of p premises. Suppose that ...
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184 views

Why do we need model theory to express semantics?

https://en.wikipedia.org/wiki/Model_theory Why can't semantics be directly expressed in the formal language? This is the key part of model theory that I don't understand: https://www.lesswrong.com/...
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Can you divide the natural numbers in half sequentially? [closed]

My brief stint on SE has been quite interesting because it forced me to make the premises of my inquiry more explicit. I resisted this initially simply for reasons of economy, but economy proved to be ...
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188 views

Human in Outer space [closed]

Is it true that human in outer space can't differ right side and left side? Around human no another solid. Thanks.
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1answer
70 views

Fitch Arrow Proofs [closed]

Using the FITCH program and the FITCH derivation rules you should make a proof or derivation of C10 from P5 through P11. P5: ∀x∀y(StrongPref(x,y)→ ¬StrongPref(y,x)) P6: ∀x∀y∀z((StrongPref(x,y)∧...
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64 views

practical example of Limitations of Predicate logic [closed]

Discuss the limitations of predicate logic. Cite practical example to support your answer.
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227 views

A concept in which an infinite force is also limited

Edit (complete rewrite): OK so I'm completely rephrasing the question. Let's begin with declaring the concept in hand - A is an infinite, willing, creation force. A "wants" to create all the ...
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1answer
116 views

Why can't type theory be applied on personality types? [closed]

Given that type theory is a system for describing mathematics, and given that "Math can be applied everywhere", why is it that type theory can't seem to be applied to personality type theory? I've ...
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149 views

How to interpret these Jain statements in terms of omega consistency? [hint only] [closed]

ω-consistent theory: In mathematical logic, an ω-consistent (or omega-consistent, also called numerically segregative1) theory is a theory (collection of sentences) that is not only (...
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2answers
204 views

Changing Universe vs Infinity: [closed]

If we accept the idea of a dynamic, changing, evolving Universe (Big Bang Theory), must Infinity remain entirely conceptual? If the Universe is changing and evolving, this necessarily implies borders ...
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1answer
21 views

Trouble with cookies

Matter cannot be created. Cookies are matter. So cookies cannot be created. I know this seems absurd but I'm using this to make an important point about arguments. The argument appears to be valid ...
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1answer
106 views

Why do I consider logic to be so important? [closed]

I note logic's nature to be contradictory. How there's no meaning in everything, so overall logic isn't considered more fundamental to the universe, but in the same arguement I rely on logic for ...
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Is it possible to mathematically define a hypercomputer-universe where things that could not be computed by it could exist? [duplicate]

There are a few physicists that propose that the universe is a hypercomputer. One example is Roger Penrose, who, basing in his quantum interpretation (https://en.wikipedia.org/wiki/...
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4answers
210 views

A difficulty I've had with this “This sentence is false” and Russell's Paradox [closed]

I'm not sure if I'm engaging in some sort of circular logical trap but I don't really think "this sentence is false" is all that logically problematic. But it would be helpful if someone could fix up ...
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179 views

Is Sacrifice a Hypocritical Self-Brainwashing Concept? [closed]

Parents of a doctor have been known to declare that they sacrificed a lot to put their child through school to become a doctor. They cite sacrifices such as not taking vacations, not buying alcohol, ...
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Is this theory for refuting the second law of thermodynamics logically valid and sound? [closed]

The second law of thermodynamics essentially argues that "usable energy is irretrievably lost in the form of unusable energy". However, we can refute this, primarily because of the universe we exist ...
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1answer
102 views

Morals - Glitch in your system penalizes user undeservingly - do you compensate? [closed]

I was wondering if it is the practice to compensate a user for a glitch in your system that penalized them. Namely, if Stack Exchange had a glitch which caused some of my awards to disappear, should ...
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2answers
255 views

Thieves are they who do theft [closed]

Thieves are they who do theft. Theft is when A takes from B what belongs to B without B's consent. Gov't takes from B what belongs to B without B's consent. What is Gov't then?
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Why do the professional mathematicians believe blindly in so meaningless concepts as Infinity? [closed]

To refute such a concept as Infinity (or many infinities) in mathematics doesn't at all require all that big efforts mainly from its own definition in mathematics. To explain this very simple fiction ...