Questions tagged [philosophy-of-logic]

Philosophy of logic is a branch of philosophy concerned with investigating the nature, scope and role of logic.

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Are all Informal Logic really just Formal Logic in disguise?

Are all systems of informal logic really just systems of formal logic that have not yet been understood mathematically?
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Quantified Logic and Unquantified Modal Logic

Is there a need to study unquantified modal logic if one knows the quantified PC logic very well? There seems to be an obvious connection between Possibility and the Existential Quantifier, and ...
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What is the difference between a logical truth and a tautology?

Some papers I read seem to be referring to a distinction between logical truths and tautologies. At first I thought something was wrong since I thought they are the same by definition. I checked the ...
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In predicate logic, do we necessarily have to restrict the domain of discourse?

Can we combine formalized statements in predicate logic from widely different domains of discourse (say, one regarding integers, one regarding the fruits in one's garden) by using logical rules/...
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The sea battle paradox and the soundness criterion

Again a short look at Aristotle's resolution (one of many) of the sea battle paradox: In one famous example about a hypothetical sea battle, [Aristotle] observes that the necessary truth of a mere ...
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Getting started with reading papers in (philosophical) logic

I have worked through some textbooks thus far, but would like to get started reading papers in the field of logic. Can anyone recommend any papers or how I could get started? I found that many papers ...
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List of journals on Informal Logic

I have a list of ideas on informal logic, which I wish to publish. Could anyone give me a list of journals on informal logic? So far, I was able to find: http://www.informallogic.ca/ But, I am not ...
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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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What is the truth value of a unevaluated truth functional?

I was trying to understand the truth functional definition of an implication "if A then B"/"if A, B". I was reading Stanford encyclopedia of philosophy article on indicative conditional and in the 3rd ...
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Believing in Humans but Not in Reality

I find it odd that some in the philosophic world won't commit to admitting reality is a reality, however they will wholeheartedly believe in a human who declares reality an impossibility. What am I ...
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Are philosophical claims grounded in the observations of the material world around us? (With regard to supernatural claims)

A commentator recently made this observation: When someone proclaims truth of the supernatural through philosophy and logic, I think of the people who follow their GPS into the lake. Now I'm not ...
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What problems get mis-conceptualised when we impose set theoretical assumptions on them?

While classical mechanics has a logic that is based on a Boolean algebra of subsets of the state space, Quantum logic is based on the subspaces of a complex Hilbert space. https://en.wikipedia.org/...
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Do logically incoherent statements still have meaning?

My reading of Carnap's "The Elimination of Metaphysics Through Logical Analysis of Language" suggests to me that it is possible to form sentences in a language that are grammatically correct but ...
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What are lucid examples of non-truth functionals?

I wanted to understand the concept of non-truth function (which I found when reading about conditionals in logic). The definition of non-truth function that I have is (from reddit): If a connective ...
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Why did we define vacuous statements as true rather than false?

I have been trying to understand why implications about the empty set are treated as "true". It seems to me intuitively that vacuous statements should be false. For example consider the sentence: ...
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Putnam's argument against the possibility of nominalising 'distance-statements' in “Philosophy of Logic” (1972)

In chapter V, The Inadequacy of Nominalistic Language, of Philosophy of Logic (1972), Putnam argues that there can be no nominalistic "translation scheme" of sentences of the form "the distance ...
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How do we know that if the statement “A → B” is correct, “¬B → ¬A” is correct?

All examples that I can come up with confirm that If "A → B" is correct, "¬B → ¬A" is correct, but is it possible to rigorously prove that negating a true implication always will result in another ...
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559 views

What is the intension of the concept “intension”? [closed]

I think that it should be possible to assign to all concepts a plausible intension, consisting of just one or two words. However, in textbooks or encyclopedias I never found such focused appointments ...
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Logic and Computation: a philosophical viewpoint on Curry-Howard isomorphism

The link between logic and computation is stronger than ever, especially since the establishment of the Curry-Howard isomorphism specifying that proofs can be seen as programs and formulas as program'...
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Necessity and sufficiency of conditions [duplicate]

Is it possible that some condition is not necessary but yet sufficient? As far as I know a sufficiency entails necessity. If something is not necessary then it can not be sufficient. Is that right?
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References for the Realism/Anti-Realism debate in Logic

The concept of anti-realism in logic seems to be an interesting and growing idea. I'm looking for references (papers, books, authors...) regarding the debate between realism and anti-realism but ...
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Prerequisites for Michael Dummett texts

I want to read Michael Dummett's The Logical Basis of Metaphysics. Is it hard to read ? I would like an answer for the same question regarding his other texts. Do I need a prior exposition to other ...
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What are the differences (if any) between classical and modern predicativity

I am researching Predicativity and I've encounterd defenition for classical predicativity and for modern predicativity but I can't understand the differences between them. Thanks
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Is finding truth possible?

Consider the following argument: If want to know that something is true, I need to first know what is truth. If I need to know what is true, I need to find the truth. (Is there ...
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Can you list examples of problems that can not be solved within a formal system but human beings have solved through construction or creativity?

This kind of problem is mentioned in a book I have read, but the book did not give a concrete example. If any such problem existed, this might help me understand human creativity. I think it would ...
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Some questions on “context” in Mathematical Logic

Recently I was having a discussion with user21820 in this chatroom. There very naively (in the sense that I didn't choose carefully each word of my following statement) I expressed the opinion that, ...
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How come intuitive thinking is related to constructing a proof?

I am researching Constructivism and Intuitionism. I can't understand why Intuitionism and Intuitionistic Logic are named as they are. Intuitionistic logic requires constructing a proof of every ...
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References for the justification of the use of Logic

Following that question : How to justify the use of logic? I'm looking for references of the justification of the use of Logic (the question above didn't ask explicitly for resources but rather for a ...
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527 views

What book recommendations for learning Hegel and Wittgenstein?

I'm currently interested in Hegel's Dialectic and Wittgenstein works. I'm mostly looking for things related to logic, language and the foundation of mathematics. What do you think I should read from ...
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Does the Fallacy Fallacy make logic useless?

I should add that I'm not a formal student of philosophy and haven't studied it in any serious depth. I just like logic, and logical fallacies. I like to spot them, and I like to debate using them, ...
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Can Second Order Logic (SOL) be a fundamental logic?

I was wondering, can Second Order Logic (SOL) be a fundamental logic? I am trying to gather some opinions from both sides to see what others might think.
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What is the study of systems (like logic, maths etc) called?

Before I begin, what I mean by 'systems' is what I've dubbed 'axiomatic systems', those which act as the starting point for all knowledge, for which I know of three: Maths, Logic, and Set Theory. I'll ...
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Is there anyone who believes that all modal statements are meaningless or trivial?

It is often useful to interpret statements in various modal logics using possible-world semantics. For instance "it is necessary that P" means "P is true in all possible worlds", "it is possible that ...
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What type of definition is “the 'death penalty' is just state-sanctioned murder”?

I'm between two choices: 1.) theoretical definition: this type of definition attempts to provide an adequate understanding of the thing(s) to which the term applies. I think this because murder is ...
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P <=> (Q v R), P, -Q⊢R Propositional Logic Question

<=> is bi-conditional, "-" is negation, "v" is disjunction. I can't figure out where to take it from line 4. Negated Q is throwing me for a loop. P <=> (Q v R), P, -Q ⊢ R P <=> (Q v R) P ...
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Is Modal Logic Logic?

What makes "Modal Logic" Logic? Why are symbols that stand for "necessary", for example, taken as symbols of Logic (of the same level of symbols that stand for "exists")? What are the limits that ...
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Why is this argument logically valid?

Premises: If Ron went to the store, Ron would be home by now. Ron isn't home yet. Conclusion: Ron didn't go to the store. I am studying the first logic course in the university. I don't ...
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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 ...
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Is this proposition analytic or synthetic?

Consider the following statement: Cats have four legs This is an analytic statement, since its truth can be established by looking at the subject and predicate; one does not need to look further ...
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What are the differences between philosophies presupposing one Logic versus many logics?

I was wondering in light of the historical developments of logic since ancient Greeks and well into the nineteenth and twentieth centuries: What kind of a philosophy assumes only one Logic, and what ...
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What is the axiom of reducibility? And what philosophical controversies did it incite?

Trying to come to terms with basics concerning philosophy of logic, and wish to ask about some particular issue: What is in simple words the axiom of reducibility put forward by Russell? And what is ...
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What are the current topics in philosophy of logic?

I'm contemplating another attempt at completing my long delayed MA in Philosophy, and I need a new thesis topic. As a student I excelled in advanced symbolic logic, but my connection with academic ...
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What distinction is there between logic, philosophy of logic and philosophical logic?

I'm not clear on where logic in the broad sense of the word stands with respect to philosophy. I do know there is mathematical logic which would be a subset of something. If philosophy of logic and ...
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Ontological status of variables

Background This question has its origin in this post. More specifically, in giving answers to the following questions, In what way does the collection of all sets consist of sets? What are ...
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What does the truth-value of a material implication represent?

This question comes from my attempts to understand what the truth value for a material implication with a false antecedent represents. I have seen several justifications for this convention, usually ...
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What is the origin of the truth table in logic?

Specifically for the material implication if possible. Who was the first to use a truth table for this and justify its validity?
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What is the explicit reasoning behind proof by contradiction?

From my understanding, proof by contradiction consists of the following steps. 1. Show that p -> q, where "->" is the conditional. 2. Show that q is false. 3. Deduce from a truth table that p must be ...
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Can one be a Modal Realist without also having to incorporate the existence of impossible worlds?

I know Modal Realism well enough itself, and have read many of the objections (and subsequent responses) that David Lewis himself took up in relation to the philosophical position. My question is, do ...
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What does the term “mathematical logic” mean?

What is "mathematical logic"? Is it the logic of mathematical reasoning, or is it the claim that mathematics and logic are identical? Also, is "quantificational logic" a particular type of "...
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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 ...