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

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What is the relationship between “truth” and logic?

I'm fairly new to logic. What I've surmised from the book I'm reading is that Logic is the science of evaluating arguments Arguments are composed of statements Statements are sentences that can be ...
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Are syllogisms independent of humans?

For example, if "All a are b" and "All b are c" then "All a are c". To make this syllogism, does a conscious being need to exist? Or is it inferred from the sentences?
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Do premises need to be valid conclusions themselves?

I'm pretty new to logic. I recently purchased "A Concise Introduction to Logic" by Patrick Hurley based on reviews. So far I'm liking the book. I'm really focusing hard on the first chapter to get a ...
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Is causality a type of necessary and sufficient condition?

Does 'A caused B' mean that A is a necessary and sufficient condition for B? Imagine that we go to a shop and buy two items with a total cost 40 dollars (30 for 1st item and 10 for the 2nd). Is the ...
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Is coherence subjective

When an argument is dismissed by an individual for being incoherent, is there an objective standard to which coherence can be held? I'm trying to determine the difference between the statement "that ...
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88 views

Philosophical feminism and logic

Are there any resources to study about academic works on philosophical feminism and logic?
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134 views

How can “who is the creator of god” question make any sense?

Whenever the god as a first cause discussion comes up, somebody posts the rebuttal: "If everything needs a cause, then what is the cause of the creator god?". Let's define the universe as everything ...
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The possibility of talking about logic

I often come to think about the limits of logic, and the idea of thinking outside logic - but that seem like a very odd thought, as logic is suppose to represent our way of thinking, so to say "think ...
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Is Deductive Reasoning Alien to the Material World?

A quick survey of literature: Goel V. Anatomy of deductive reasoning. Trends Cogn Sci. 2007 Oct https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2685028/ García-Madruga JA, Gutiérrez F, ...
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Justification of deductive reasoning

Is a justification of deductive reasoning possible? If so, please tell me how because whenever I try to form a justification of deductive reasoning I end up committing the fallacy of circularity.
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54 views

Clarification with material conditional , logical necessity and causation

Are the following four statements always true - (1)If Proposition B is the Logical consequence of proposition A, then B is material conditionally connected with A. (2)If Proposition E is ...
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53 views

Does the individual meaning of two propositions determine or constrain what kind of logical connectives can be formed between them?

What is the basis for the definition of logical connectives? Are they just arbitrary convention? Or does it depend on the meaning of the constituent propositions? Does the individual meaning of two ...
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What justifications have been given for using particular systems of logical calculus?

I think that using any particular system of logical calculus should be properly justified. This justification should be seen as particularly important and pressing in science and technology, and ...
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Do mathematicians take Modern Logic to be an appropriate representation of our sense of logic?

What examples do we have of mathematicians who explicitly and publicly expressed their personal confidence that mainstream modern logic, as used in mathematics, either as object of study in itself or ...
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On Putnam's belief that we can choose a logic system based on the task at hand

I was reading "A Graphic Guide to Logic" and a little speech bubble from Hilary Putnam says that "I still believe that there are facts in the world that determine which logic it is appropriate to use ...
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Is the set of all true contingent propositions equal to the set of all true propositions?

Since the conjunct of a true contingent proposition and a necessary proposition is contingent and hence it is contained in the set of all contingent propositions. Does that mean that the set of all ...
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308 views

How different would mathematics and science be if we'd assume truth does not exist?

This comes from the question "Is human intuition consistent with current structure of mathematics?" I asked myself. Intuitively we agree on very many things and it seems we can "prove" almost ...
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What, at present, are the major unsolved problems of logic?

In the 1900s, Hilbert published a list of 23 (later 24) unsolved problems in mathematics, which sparked increased research into each of them and the subsequent resolution of several of these problems. ...
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Why is Truth the default designated value in logic and language?

It seems that investigations of language and logic have focused on truth as the assumed designated value (the value preserved by valid entailments). It is only in later, non-classical logic that non-...
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What is the relation between expressive completeness and semantic completeness

A formal system is expressively complete if and only if it is capable of expressing, as a formula, everything that is the subject of that formal system. A deductive system is semantically complete if ...
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Is the Completeness of a logical system considered an integral part any 'good' logical system?

Most logical systems will have two distinct forms of entailment, one is system-based entailment (logical consequence), and the other is proof-based entailment (derivability). In the former, an ...
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The flaw of disproving the extreme by citing the norm

Let me first begin by saying that I do not have a formal background in philosophy. I was looking into formal logic and common fallacies and could not find a formal framework for the following ...
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If the premises of an argument CANNOT all be true, then said argument is valid

Based on the fact that a deductive argument is said to be valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false, I am ...
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Why do we seek to “limit” our scope for the search after truth?

In philosophy and science, we quite often make systematic approaches that limits our thoughts to be as accurate as possible. Examples are endless - basically every logical system, every ...
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Would you know if an answer is 'illogical' or just 'incomprehensible' (to you)?

I've seen good answers up voted and brilliant answers down voted. I understand that not everybody has the same intellectual ability. And, we do not know, what we do not know. Good answers are ...
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Can you imagine a completely different logical/mathematical system than that we have?

Can you imagine a different logic and mathematics? For example, with a different arithmetic, or even a universe with no logic or mathematics and contradictions? A non consistent system?...
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How could mathematics and logic exist without us, if they are concepts created by us independent of reality?

Would maths and logic exist if we didn't exist despite we created them, and do not have correspondence with reality?
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What do we mean when we say there's only one type of logic/mathematics and that they can’t change?

Do we want to say that if they changed, they would not be logic/mathematics (as we know) anymore? How can we be sure that there's no other type of logic/mathematics?
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Does computer science have an impact on Philosophy?

Recently I found some books in the domain "Philosophy of Computer Science." However, the majority of these books described how the logic and analytical philosophy can develop and understand computer ...
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Philosophy of Time

I have a question about time. What philosophical arguments can be presented for the reality of time? And I would like sources to be posted too. It is confusing me.
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Can 2 logical deductions starting from 2 different and independent sets of assumptions lead to 2 contradictory conclusions?

Can two formal logical deductions A and B, starting from different sets of assumptions H1 and H2 (if it helps, consensual facts about reality), each of them independent (that is, they don't imply any ...
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264 views

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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113 views

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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476 views

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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378 views

What is the nature of Logic? [closed]

Is Logic an eternal aspect of the reality, sovreign of the thoughts of our brains. Or is it something that exists inside our minds and is not real? Say, for example: 1 stone is less than 2 stones -> ...
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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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247 views

Is the Halting Oracle Inconsistent

Axiom of Consistency (Axiom 1 of the Multiverse Axioms): All universes are logically consistent and strictly adhere to well defined laws. Is the Halting Oracle inconsistent? Basically, ...
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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 ...