Questions tagged [logic]

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

281 questions with no upvoted or accepted answers
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271 views

Why isn't humanistic logic taught in schools any more?

Specifically, I'm curious about the loci or categories that Agricola and later Ramus used extensively. Were they found to be problematic at a later time? If not, why not use them? They're so helpful ...
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1answer
218 views

Which problem is Russell focusing on while providing a solution, in his introduction to the Tractatus?

In the final part of his introduction to the Tractatus Logico-philosophicus, Russell provides a possible solution to the problem of the impossibility of self-reference of logic: There is one ...
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1answer
49 views

Approximately directed graph of logic types

I'm not sure if this is the right stack to post this question. Given there are many types of logic; Syllogistic, Symbolic, Modal, Deontic, Temporal, Epistemic, (non)monotonic, formal, informal, FOL, ...
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91 views

The enunciation clause (Lyotard & Levinas)

As kind of introductory remark, let me state that I'm not academically-trained in philosophy, so my apologies if this comes up as a rather simple question. I was reading Logique de Levinas by JF ...
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285 views

How do disjunctive antecedents work in Marc Lange's stability concept of laws of nature?

I'm an ecology student who's dabbling into philosophy of science. I'm currently writing a term paper on laws of nature (with a focus on ecology as a special science) and try to wrap my mind around ...
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3answers
414 views

Is it possible for an argument to be logically valid but not truth-functionally valid?

Truth-functionally valid: there is no truth value assignment for which the premises (of an argument) are true yet the conclusion is false. I am told that there are arguments which are logically valid ...
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1answer
426 views

Is Tarski's derivation of the Liar paradox valid?

First a link to his derivation: http://www.jfsowa.com/logic/tarski.htm Its a famous essay so you really should read all of it but at the moment its enough if you read section 7 where Tarski derives ...
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62 views

Is there a “for dummies” construction of the valuation model of the relevance logic R from a De Morgan monoid?

I am confused how one gets the anti-chain preserving negation in Belnap-Dunn's FOUR, which by all accounts underlies their R (which adds implication), when R's valuation model is constructed from a De ...
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1answer
181 views

Rewriting a set of propositions that includes a circular proposition

"For any proposition P, if I believe that P then this paragraph (everything that is written between the quotes) entails that I believe that P. I believe that I exist. For any proposition P, if I ...
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179 views

Grice: Comparing Natural Meaning, Non-Natural Meaning, Conventional Implicature and Generalized Conversational Implicature

I am currently reading "Meaning" and "Logic and Conversation" by Paul Grice. I find it a little difficult to differentiate clearly between his concepts "natural meaning", "non-natural meaning", "...
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1answer
142 views

Does Tegmark himself include paraconsistent mathematical structures in his mathematical multiverse hypothesis?

Tegmark postulates in his hypothesis that all possible mathematical structures would exist. But does he include also possible mathematical structures described by other types of logic like ...
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79 views

Are there degrees of rationality/plausibility to assumptions?

There are many kinds of premises, in every possible field. I'll limit this question to metaphysics, although it can definitely be applied to each and every scientific/philosophical study. For example,...
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85 views

What to read for an introduction on the epistemology of logic?

I would like to read about the epistemology of logic, preferably at a undergraduate level (not being a philosopher myself). What (text)book should I read for a good introduction on these topics? The ...
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86 views

Is a Thomist possible modal proposition a non-judicative proposition?

According to Thomist philosophy and logic, is a possible modal proposition (either divisive or compound) a non-judicative proposition? It would seem to me that the other three modal propositions (...
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466 views

What are some of the best books for a robust introduction to Logic and Critical Thinking?

As the question states: What are some of the best books for a robust introduction to Logic and Critical Thinking? My background: I'm 24, graduating with two degrees in Political Science and ...
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79 views

What questions or areas in the foundations of mathematics remain active research fields?

By foundations of mathematics I am referring to the mathematical, logical, and philosophical foundations of the subject. I'm interested in seeing which of these have active research going on within ...
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146 views

Can Kant's antinomies be translated into formal logic?

Kant proves the limits of human reason by providing 4 antinomies, pairs of rational but contradictory statements, which he claims pure reason can never help us decide which one of the pair is correct. ...
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1k views

Testing the validity of syllogism argument

I came across a validation method for testing the validity of a syllogistic argument which seems quite easier to grasp: For example: To test the argument: no P is B some C is B Therefore, some ...
3
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1answer
136 views

Is Logic Pre-Human?

It was German philosopher Martin Heidegger (1889-1976) who famously said, "animals are poor in world." Although this may be true, I do not see them as being poor in logic. Paleontologists have ...
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4answers
537 views

Are opinions considered statements?

‘Aristotle was great’. Is this a statement? I consider a statement to be something either true or false (but not both). For an individual, this may be considered a statement (because either you ...
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111 views

Given the principle of innocence, how shall we explain logic's usefulness?

I have been reading Florian Steinberger's dissertation (Harmony and logical inferentialism) and I come across the following on p60: ...two fundamental assumptions (the other one being the principle ...
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1answer
103 views

Looking for references for some remark of Quine's

I'm looking for a comment I think I remember Quine having made. He's talking about our understanding of proofs. I think he says something along the following lines... If you understand many different ...
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37 views

Summary of philosophical positions on how belief revision proceeds in mathematics?

Since mathematicians have embraced classical logic, as e.g. MacFarlane points out in his 2021 intro book to philosophical logic (§ 7.4), one needs to distinguish between [meta-]reasoning and argument/...
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Analysis of Liar-like sentences in fuzzy logic

Let t0 = FALSE and t1 = TRUE. In fuzzy logic, 0 or 1 can be switched out for any real number in the interval [0,1]. This lets us construct all manner of liar/honest-like sentences, ranging from, "...
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Has there been any philosophical interpretation (or application) of Stone lattices?

Stone lattices/algebras are Heyting (i.e. intuitionistic) lattices in which both laws of De Morgan hold, or equivalently, Heyting lattices in which also ~p \/ ~~p = 1. While these have been studied a ...
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Is there a taxonomy of disagreement types?

In philosophy, is there any type of taxonomy of types of disagreements? For example, I want students to look at varying takes on a subject. What I want them to focus on is, Why do such smart people ...
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43 views

What is 'expendable' in logic and how to explain 'tautology' given this image?

This image is from http://www.nfillion.com/index.php/teaching/9-logic-112. According to this, a proposition can have 4 basic properties: (1) necessarily, (2) not possibly, (3) missing, and (4) ...
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54 views

How does Davidson's Slingshot argument escape Russell's Theory of Definite Descriptions?

Hi I am trying to understand Davidson's Slingshot argument. Apparently it is said that Russell's Theory of Definite Descriptions does not face the problem that Davidson highlights. For instance, if we ...
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40 views

Philosophical meaning of the Curry Howard Correspondence

At a technical level, I understand the Curry-Howard correspondence in various settings, and its usefulness as a technical tool. What I'm looking for is a fairly rigorous discussion of genuinely ...
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1answer
90 views

How does Consequentialism handle uncertainty?

E.g. Suppose you are a Consequentialist faced with a variation of the trolley car problem. Your options are to save five people with a 20% likelihood or one person with a 100% likelihood. Which option,...
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39 views

Did Quine change of opinion towards quantified modal logic?

Willard Van Orman Quine was a strong opponent to quantified modal logic calling it unreasonable and useless. But, did he always think like that? Or did he relax his attitude towards it with time? Did ...
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105 views

Is there a logical argument for the limit of knowledge?

It is justifiable to assert that certain knowledge could not be disseminated without the invention of writing. One could say that humanity needed the knowledge of writing before further knowledge ...
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3answers
148 views

Does anyone have an example where a sufficient condition comes first?

Example: Sufficient Condition of A+ MUST MEAN Necessary Condition of Studying occurred Temporally speaking, either condition can occur first, or the two conditions can occur at the same time. In our ...
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61 views

This statement is in a disjunction with itself

Are the following listed statements equivalent? 1: (1) is in a disjunction with (1) 1: (1) is in a disjunction with (1) OR 1: (1) is in a disjunction with (1) (the intended meaning of (1) is '...
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Thoughts on Open Logic Project?

I'm currently thinking about starting to expand my knowledge of logic beyond what I retain from my previous study of logic by making use of the materials available through: OpenLogicProject (https://...
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43 views

The name for an anticipatory counter-argument?

There's the argument ad absurdum along with several other kind of reasoning. What is the name for a forestalling counter-argument - an argument put forward pre-emptively in anticipation of an ...
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50 views

A Paradox for Anti-Realism?

Semantic Anti-Realists hold that a claim has a (constructive) proof if the claim is true. I wonder whether this position runs into a version of Yablo's supposedly non-circular version of the liar ...
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53 views

How disjunction works with the conditional excluded middle

I'm studying the semantics for counterfactuals, and I'm slightly confused about how certain inferences supposedly make the Conditional Excluded Middle (CXM) fail. Formally, we can write the ...
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63 views

Can a Rigid Designator still exist if there is only one possible world?

According to Kripke, a rigid designator is a pronoun (but not all pronouns are rigid designators) and they pick out the same unique individual in each possible world. I understand this, however, if ...
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127 views

Language confusion; necessary/nomological/true in all worlds

I got confused by the way different people use language in the context of physicalism. In particular, Kripke seems to equate "necessary truths" with something that is true in all possible worlds. Is ...
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125 views

Modal logics - philosophical paradoxes using modeling by possible worlds

I'm searching for "paradoxes" in classical modal logics, meaning lines of reasoning which give a counterintuitive conclusion if performed in classical logic, which can be modelled by the (semantical) ...
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60 views

De Re, Counterfactuals, and rigidity

This is going to come off as vague or obscure; but, I hope the idea is performatively expressed: Two questions: Do you think that Kripke would argue that the impossibility of de re counterfactuals ...
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53 views

Circularity between truth and meaning?

These two common claims are equally appealing: (1) the meaning of a ( declarative) sentence consists in its truth conditions (2) the truth of a sentence depends on its meaning But are we moving ...
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79 views

Is there an Abstract/Concrete Gray Area?

In natural language and daily life, it has become prevalent there is a class of entities which do not follow the abstract concrete distinction. Many people refer to abstractions that exist in time. (...
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53 views

How did Aristotelian logic view this?

I am very interested in the logical aspect of Aristotelian philosophy, especially how it was used by al Farabi and Ibn Sina in explaining understanding and breaking this complicated process down ...
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666 views

Why is a square circle metaphysically impossible?

We have definitions for both a square and a circle. By definition, I understand that it's impossible to have a square circle. However, why does the word 'square' have to necessarily mean 'a plane ...
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103 views

Why don't two equivalent propositions contribute to the same semantics?

We often have 2 propositions that have the same truth table, in that they are true and false given the same conditions. Nevertheless, we still feel as though there different semantics (i.e meaning..),...
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140 views

What are the consequences of rejecting identity of indiscernibles

What kind of system are we in if we explicitly take its negation as an axiom? Here's the identity of indiscernibles. (1) ( ∀P.P(x)↔P(y) ) → x = y Here it is written in prenex normal form (2) ∀x∀y.∃...
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207 views

Does Reflective Set Theory “RfST” fulfill the requirements of founding Category Theory and Mathematics?

On mathoverflow I've posed the question in the title in connection to Muller's 2001 criteria for a founding theory of mathematics, which largely raised in connection to Category theory [see here]. ...
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Why can't existence be expressed in linear temporal logic?

In some circumstances, existence cannot be expressed in linear temporal logic. I don't understand why it can't be constructed with negations and global quantifiers. For example, the wikipedia page (...

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