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Questions tagged [logic]

Use this tag for general questions about logic that are not categorizable under some more specific tag, like "mathematical logic", "informal logic", "classical logic", etc.

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37 votes
10 answers
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Is it a fallacy if someone claims they need an explanation for every word of your argument to the point where they don't understand common terms?

Is it a fallacy if someone claims they need an explanation for every word of your argument to the point where they don't understand common terms? For example, suppose someone said, "If a dog bites ...
dogperson's user avatar
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32 votes
10 answers
11k views

Isn't the notion that everything will occur in an infinite timeline an example of the gambler's fallacy?

I've seen a few different formulations of this, but the most famous is "monkeys on a typewriter" - that if you put a team of monkeys on a typewriter, given infinite time, they will ...
Lou's user avatar
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32 votes
10 answers
294k views

What is the difference between Fact and Truth?

I'm curious about the difference between Fact and Truth. I was searching on the internet if I could find it. But still I'm confused about the exact meaning. I first read the forum discussion here Fact ...
NullPointer's user avatar
30 votes
1 answer
22k views

Difference between implication/conditional and logical entailment?

What is the difference between the implication/conditional truth function and the notion of logical entailment? My naive understanding as a computer programmer is that the conditional is a function ...
user's user avatar
  • 457
29 votes
4 answers
5k views

Where is the weakness in the ontological proof for God's existence?

I read the ontological proof for God's existence. As much as I understood, it says that if you consider that existence is part of essence, then the most complete essence should also exist. Now, I see ...
Saeed Neamati's user avatar
28 votes
7 answers
50k views

What is the difference between a statement and a proposition?

I'm doing a MOOC on mathematical philosophy and the lecturer drew a distinction between a proposition and a statement. This is very puzzling to me. My background is in math and I regard those two ...
user4894's user avatar
  • 2,957
28 votes
9 answers
27k views

Is infinite regress of causation possible? Is infinite regress of causation necessary?

For a number of reasons — including perhaps a desire to feel that we have a complete understanding of where we came from, or at least an understanding which is completely sufficient for all of ...
Niel de Beaudrap's user avatar
28 votes
4 answers
6k views

What are the philosophical implications of category theory?

I have heard about topoi being the ideal entities to use for foundations of mathematics (since we are able to reasonably interpret our theories in them), so I imagine there might possibly be some ...
Dejan Govc's user avatar
27 votes
16 answers
2k views

Is the claim "this coin is fair" falsifiable?

Wikipedia says, The claim "No human lives forever" is not falsifiable since one would have to observe a human living forever to falsify that claim. Thinking on similar lines, even if the ...
AIB's user avatar
  • 1,551
27 votes
3 answers
2k views

What are the major research programmes in contemporary logic?

As an interested outsider who is prone to reading about different formulations of logic, I've become interested in better understanding the big picture of what people are trying to accomplish as they ...
Niel de Beaudrap's user avatar
26 votes
7 answers
5k views

What type of rhetorical device is the offering of a source which is really long and not specifying what part of the source is relevant?

I'm encountering a frequent recurrence of a rhetorical device that seems to me fallacious but I can't figure out what it's called. When making an argument, the person does the following: Makes a ...
Kiril's user avatar
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26 votes
3 answers
19k views

What is modal logic for?

I understand "pure" logic as a structural description of what a valid proof is but I have never understood the reasons for using modal logic. What's an example typical of how modal logic is used?
user avatar
25 votes
12 answers
13k views

How is gun violence comparable to drunk driving?

I just read "Is 'guns don't kill people people kill people' a good argument?" and it reminds me of another argument. I would like your opinion on whether or not it is a good argument. Gun Control ...
Malachi's user avatar
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25 votes
2 answers
11k views

What is the difference between "reductio ad absurdum" and "proof by contradiction"?

What is the exact difference between reductio ad absurdum and proof by contradiction? Wikipedia used to state that: Reductio ad absurdum (Latin: "reduction to the absurd") is a form of argument in ...
loudandclear's user avatar
24 votes
2 answers
29k views

What fallacy dismisses problems by presenting "bigger" problems?

Wasn't really sure how to phrase this, but I'm thinking of an instance in which someone diminishes a problem by presenting one of larger scope - as a rather shoddy example, "x political problem in ...
user2871915's user avatar
23 votes
11 answers
13k views

Is Yoda committing a fallacy?

I've been debating with a hard core Star Wars friend who loves repeating Yoda's "Do or do not, there is no try" knowledge. I tried to explain that the DO (B) and DO NOT (C), are end results, ...
Beach Bum's user avatar
  • 355
23 votes
12 answers
3k views

Motivations for dialetheism?

At the request of the moderators, I've reformulated this question to change the emphasis of the question to something perhaps a little more broad-ranging: Question. What are the major modern ...
Niel de Beaudrap's user avatar
22 votes
5 answers
10k views

Why does "Daisy has four legs" not entail "Daisy has more than two legs"?

I have been going through one of the books and I found an example of conclusion C that is not entailed by a premise P. Daisy has four legs. So daisy has more than two legs. Surely though, the ...
bodhihammer's user avatar
  • 1,096
22 votes
10 answers
15k views

Can an argument be valid even though one of its premises is false?

Is it possible for an argument to be valid by virtue of its logical form, but contain a false premise? In other words, can a premise be false even though the argument itself is logically valid? ...
Curious 's user avatar
22 votes
9 answers
4k views

What is this fallacy: Perfection is impossible, therefore imperfection should be overlooked

This is a pretty common fallacious statement that people make every now and then. Point me to any software that has been released without bugs? I think your expectations might be a tad high. It's ...
user1883337's user avatar
22 votes
12 answers
22k views

Are omniscience and omnipotence mutually inconsistent?

I see this in The God Delusion by Richard Dawkins: If God is omniscient, he must already know how he is going to intervene to change the course of history using his omnipotence. But that means ...
Yashar's user avatar
  • 329
22 votes
8 answers
9k views

What fallacy is this? “This happened, therefore there must be good reasons for it”

What fallacy is it when someone says "this is true/it happened, therefore there are good reasons for it"? For example: We drive on the left (or right, depending on country) side of the road, ...
David Balažic's user avatar
22 votes
12 answers
6k views

Could law be written in formal logic?

I essentially have two questions: Could law be written in formal logic? If that's indeed possible, should it be? I see possible drawbacks being: Difficulty to express certain concepts, I can't ...
paternostrox's user avatar
22 votes
10 answers
5k views

Is it a fallacy to say that a sane person cannot apply rational thought to the motivations of the insane?

A common argument in today's news is that: Someone commits a heinous crime by shooting a bunch of people. Anyone who commits a heinous crime must be insane. Sane people cannot apply rational thought ...
YPCrumble's user avatar
  • 329
22 votes
8 answers
6k views

What is this logical fallacy? (Nothing new under the sun?)

It has been two decades since I took a reason and argument course in college. I am rusty on my command of logical fallacies. With that preface, I have been trying to locate a logical fallacy that ...
user avatar
22 votes
6 answers
10k views

How is the argument "I love all logic, but I don’t love deductive reasoning. Therefore, the moon is made of green cheese." valid?

This example came up in class: I love all logic, but I don’t love deductive reasoning. Therefore, the moon is made of green cheese. I understand the premise is contradictory and the conclusion ...
user34930's user avatar
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22 votes
10 answers
6k views

Why can't humans believe contradictions?

I'm reading something on the topic of logic and one of the exercises asked me to convince myself that a contradictory statement was true. I could not convince myself of this and now I am curious about ...
James's user avatar
  • 337
22 votes
10 answers
3k views

Are different values of nothing equivalent?

Are different values of nothing equivalent? Is 'no tigers' the same as 'no zebras'?
Stephan Schielke's user avatar
22 votes
12 answers
6k views

Are there any philosophy books for an intelligent nine-year-old?

I would like to buy some books on philosophy for the child of a friend. He is very intelligent and mathematically able and clever for a nine-year-old. I remember near that age really enjoying the idea ...
Simd's user avatar
  • 320
22 votes
10 answers
4k views

Is the universe isomorphic to a universal turing machine?

I often think about problems that require an understanding of the very essence of computation and its inherent limitations. So, my questions are as followed: Is the universe isomorphic to a universal ...
Quaternary's user avatar
22 votes
1 answer
15k views

How can we reason about "if P then Q" or "P only if Q" statements in propositional logic?

When you have a propositional sentence of the form P ⊃ Q  — which we might read as "if P, then Q" — how can you tell when it is true, or false, based on the truth-values of P and ...
Niel de Beaudrap's user avatar
22 votes
10 answers
4k views

What formal logical systems "resolve" the Liar Paradox?

Short version of my question. What formal logical systems can represent, and seem robust against, the Liar Paradox? N.B. I would like to avoid reference to truth-values, except inasmuch as they ...
Niel de Beaudrap's user avatar
21 votes
15 answers
5k views

Is there any rigorous philosophical basis for atheism?

Definition/Update In what follows I use the term God to refer to an entity that has at least one of the following properties: Has created the universe Is omnipotent Is omniscient Approaches to ...
Pantelis Sopasakis's user avatar
20 votes
7 answers
6k views

Why is the selection of logical connectives {¬,∨,∧,⇒,⇔}, in set theory?

Nearly every treatment of set theory, whether Paul Halmos' Naive Set Theory, Herbert Enderton's Elements of Set Theory, Patrick Suppes's Axiomatic Set Theory, etc., introduce a common set of logical ...
EthanAlvaree's user avatar
20 votes
11 answers
20k views

What is the difference between Law of Excluded Middle and Principle of Bivalence?

Law of Excluded Middle: In logic, the law of excluded middle (or the principle of excluded middle) is the third of the so-called three classic laws of thought. It states that for any proposition, ...
Tames's user avatar
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18 votes
11 answers
22k views

Have I found a paradox, or is the universe digital? Or am I just plain wrong? [closed]

If the universe is analog, there must exist an infinite number of positions. This raises an interesting question. Let me boil it down to something familiar: a table and an ashtray. I'll let the ...
Mads Aggerholm's user avatar
18 votes
6 answers
9k views

If math is so deductive, why is it so hard to discover new math?

Some considerations: The conclusions of much latter/new math may be said to be already existent within the premises of current math The importance of deduction changes depending on if math is said ...
Xeon's user avatar
  • 489
18 votes
8 answers
6k views

Is "This sentence is written in English" nonsense?

Wittgenstein and many others have said that our language gives the appearance of truth to some nonsense. Do you think the very simple "This sentence is written in English." is such nonsense ...
François's user avatar
  • 340
18 votes
10 answers
7k views

What is the name of this fallacy: 101 is either binary or decimal?

A similar example would be of binary and decimal number where we are not sure about the number system. For example, The person who proposed a number is not remotely available to disclose about number ...
Ubi.B's user avatar
  • 320
18 votes
6 answers
6k views

Is God either amoral or not omnipotent?

The usual (Christian) justification for suffering/evil in the world created by a benevolent God is freedom of the will. However, the more interesting question is not about the source of evil (which ...
Conifold's user avatar
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18 votes
5 answers
3k views

Why does Carnap say 'Caesar is a prime number' is meaningless?

I don't get it. Assuming there exists an individual Caesar, we can look at the set of prime numbers and not-(prime numbers), and Caesar will be in one of them. I just don't see, even though it may be ...
Casey's user avatar
  • 488
18 votes
2 answers
2k views

Why did the mid-19th century and earlier thinkers fixate on one-place predicates?

A book I'm reading mentions the following: A major barrier to the development of first-order logic had been the concentration on one-place predicates to the exclusion of many-place relational ...
MWB's user avatar
  • 471
18 votes
3 answers
2k views

What is the philosophical ground for distinguishing logic and mathematics?

I was wondering why the field of mathematics and that of logic are perceived as two distinct fields. Although could be pleased with the intuition that logic is rather meta-mathematics, still would ...
L.M. Student's user avatar
  • 2,721
17 votes
8 answers
6k views

Is it fallacious to argue that something is correct, of good quality, or acceptable because a community of experts has established it as such?

Earlier today, I asked a programming question on a forum. I phrased the question as "What is the best way to do x?" Someone responded with something to the effect of, "the best way is ...
AffableAmbler's user avatar
17 votes
4 answers
6k views

Is there any worth—other than historical—to reading Aristotle's works on logic?

What I mean is that presumably a topic such as logic would have, at this point, been so advanced that the ancestral works are unnecessary. I would read it for pleasure, but have they been ultimately ...
Sermo's user avatar
  • 813
17 votes
10 answers
14k views

What is the idea behind "p or not p" being a tautology?

Most (all?) logic books consider "p or not p" to be a tautology, hence always true, and this is usually stated without any further discussion. (I never gave it a second thought.) In common ...
Sam's user avatar
  • 317
17 votes
1 answer
4k views

When it is correct to use Tarski's undefinability theorem versus Gödel's incompleteness theorem?

Smullyan (1991, 2001) has argued forcefully that Tarski's undefinability theorem deserves much of the attention garnered by Gödel's incompleteness theorems. That the latter theorems have much to say ...
Xodarap's user avatar
  • 2,798
17 votes
6 answers
3k views

What fallacy dismisses criticism of a bad law with "just don't break it"?

Let's say someone is criticizing the government for instituting some draconian policy, and/or for persecuting people for doing something minor. And the response is:"Just don't do it and you'll be fine"...
Legend of Overfiend's user avatar
17 votes
7 answers
7k views

Can a lack of knowledge or understanding invalidate a positive claim?

Consider the example of causal determinism. It can be phrased in many ways, all with identical meaning: - The idea that "every event, including human cognition and behavior, decision and action, is ...
stoicfury's user avatar
  • 11.7k
17 votes
6 answers
3k views

Is Logic Empirical?

We use the logical system that we know from observations (empirical data) holds true in the world we live in (please correct me if I am wrong). Hence the axioms of logic we choose are themselves ...
Suraj Jain's user avatar

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