Logic is the study of formal systems of reasoning, especially of the deductive variety. It is one of the few fundamental philosophical subdisciplines, along with metaphysics, ontology and aesthetics. Logic has taken on considerable importance in recent mathematical developments, and one of the ...

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are Wittgensteins propositions analytic or synthetic?

Wittgenstein provides a logical analysis of propositions in the Tractatus; does he there admit the Kantian distinctions between analytic/synthetic and a priori/a postereroi divisions; or does his ...
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2answers
94 views

Is this disproof of God's existence logical?

The apologetic claims the argument is logically valid by modus tollens. The somewhat detailed version is: Premise 1. If Argument A for God's existence is sound, then God exists. Premise 2. But ...
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3answers
75 views

How can you translate the mathematical statement 5=5 into a second order symbolic logic statement?

Hi I'm trying to describe the statement 5=5 using symbolic logic. I initially attempted to describe this into English as: There is such a thing x and such a thing y, such that x is equivalent to ...
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2answers
57 views

The dissonance between our logic, and the origin of everything

Many broad arguments, listed below, hold for the entirety of our existence, but they overwhelmingly fail to explain the edge cases - that is, the beginning and the end. For example: Energy cannot ...
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2answers
94 views

Contradictory Conclusions - Both cannot be valid

Q: Consider the following two propositions: Oswald shot Kennedy; Oswald did not shoot Kennedy. Suppose that we have two pieces of reasoning, one with the first as conclusion and the other with the ...
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2answers
81 views

Decreasing quantifiers and entailment in event semantics

Consider the sentences (1) All dogs bark. (2) All dogs bark loudly. In event semantics the logical form of (1) is (∃e,x) every(x) & dog(x) & bark(e,x). As for (2), one would ...
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29 views

Concerning the integrity of some logical syllogisms on moral subjectivism and ice-cream

I understand moral subjectivism to be the meta-ethical idea that all moral statements are merely expressions of the individual and thus that there are no moral statements that are implicitly ...
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30 views

if u guys can help in this Q's? [closed]

What is the difference between Set, and Class in object oriented languages? (a) What is the principle or law of identity? (b) What is proof in logic? Derive ¬(RvB) from ¬R and ¬B without using ...
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1answer
44 views

Eventualities and their existence

Emmon Bach uses in "The algebra of events" the term 'eventuality' to denote states, events, processes, etc. How can their actual existence be expressed logically? For example, when I say "John came" ...
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4answers
142 views

“→” is the symbol for material implication. Is there such a thing as “immaterial implication”?

Why do we qualify "implication" with "material"? This seems to imply that there are other kinds of implication.
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2answers
45 views

How should motives be ordered?

Suppose a master baker gives me a cake recipe of which the instructions must be followed in a specific order, and they are: Mix wet ingredients Mix dry ingredients Add dry mixture to wet Bake ...
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1answer
58 views

Alternate axioms for relevant logic R

Relevant logic system R can be defined -as I read in D. Palladino, C. Palladino, Logiche non classiche- by the following axioms A→A (A→B)→((C→A)→(C→B)) (A→(A→B))→(A→B) (A→(B→C))→(B→(A→C)) A∧B→A, ...
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64 views

What is the general relationship between Intelligence and Information?

I will take the definition of "information" used in the field of Information Theory, which according to my understanding of Information Theory, information is the loss of uncertainty(e.g. while a coin ...
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1answer
58 views

Another name for “non-events”

According to Davidson, a sentence like Brutus stabbed Caesar can be represented as ∃e.stab(Brutus,Caesar), where e is a reified event. Is there a term for something that's not an event? I first ...
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1answer
39 views

Representation of Categorical Syllogism in Symbolic Logic

How would I represent a AAA categorical syllogism with symbolic logic?
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3answers
106 views

For any argument form in the language of propositional logic, the tree for that argument

For any argument form in the language of propositional logic, the tree for that argument ... always closes after a finite number of steps can always be completed after a finite number of ...
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1answer
34 views

Conversion of Conditional Statement to Disjunctions

Let us say that we have the conditional statement A→B. What would be the best way to represent that in the form of a disjunction (A∨B)? Help is much appreciated.
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4answers
75 views

Is there an onus on the critic to povide an alternative solution?

In many situations, when someone criticises a procedure, or a policy, a common response is something like "yeah, we know it's crap, but you're not presenting an alternative solution, so shut up". ...
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3answers
168 views

What is the minimum number of axioms required for a system of axioms?

What is the minimum number of axioms you need, apart from definitions and usage of the notation, such that you have a system that does not contradict itself? I would just think that the answer is ...
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1answer
212 views

Are there different levels/categories of falsehood?

Consider the following sentences: The current president of the United States has 2 daughters. The current president of the United States has 5 sons. The current emperor of the United States has 12 ...
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1answer
130 views

Material vs formal logic?

I would like to know how material logic differs from formal logic. From the little that I'm aware of, it is apparently the case that material logic concerns itself with the truth of the content of an ...
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1answer
117 views

Relation between truth tables and trees

Given any argument, does the truth table necessarily contain more rows than the number of open branches in the completed tree? My gut feeling tells me no because I could always find a complex ...
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3answers
112 views

Is it possible to argue that belief systems that are full of caveats about their own predictions tend to be false?

It seems to me that many religions, especially those with Abrahamic roots: Claim that God loves us. Claim that God is very powerful. Are laced with caveats that purport to explain why a very ...
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2answers
57 views

How can I prove that any group of points created after just one point existing must exist in the same place? [closed]

How can I prove that any other group of points created after just one point existing (and not in the same place as the original one point that first exists) must exist in the same place (that place ...
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3answers
77 views

What is the principle (law) of identity and is it universal?

From wikipedia I know that the principle (or law) of identity can be stated as : A is A. This seems a pretty straightforward principle: something cannot be what it isn't. Why does this principle need ...
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2answers
151 views

Could you help me with this logic problem? [closed]

I need help proving validity of this: ((A ∧ B)∨(¬A ∧¬B))<==>(A<==>B) This is how we did it in class, but I don't actually understand this very well. Could someone explain to me how to ...
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1answer
41 views

Formalised logic equivalent of self fulfilling prophecy?

For example Will this query be answered correctly? Yes Has this query been answered correctly? A. Yes, therefore "yes" is the correct answer, therefore this query has been ...
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1answer
61 views

A∧B-worlds and law of enrichment in Stalnaker semantics

In Stalnaker semantics a conditional A↦B is true in world u if either A is not logically possible (ex absurdo quodlibet holds in the semantics) or A is logically possible and B is true in the nearest ...
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7answers
231 views

How to justify the use of logic?

I would like to hear some Philosophical arguments which justify the use of logic. Additionally, if a justification of logic takes the form of an inference, this inference itself makes use of logic. ...
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1answer
49 views

Do malformed propositions have True/False values?

Many people are familiar with the malformed questions that, no matter which way they are answered, reflect poorly on the person to whom they were asked. For example: Have you stopped beating your ...
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2answers
83 views

First book to self-learn logic, mainly to improve reading comprehension?

I read Where is a good place to start reading about logic? and ask.metafilter.com, but want to focus on improving comprehension and parsing of difficult writing. I never studied logic before, and ...
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1answer
69 views

Is this way of thinking about the differences between men and women valid? [closed]

Problem I think that there's a common message out there today driving women to think they need to be treated the same as men, and thus deny any mental differences, when the right word that needs to ...
2
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2answers
84 views

LPL Q6.26 without --> or material implication

This is a repeated question: Language Logic and Proof Q. 6.26 "Using the natural deduction rules, give a formal proof of A ∨ D from the premises A ∨ (B ∧ C) (¬ B ∨ ¬ C) ∨ D" The LPL textbook ...
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2answers
94 views

Sentential Derivation: Derive ~(RvB) from ~R and ~B

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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10answers
231 views

Does the imperfection of man imply the imperfection of God?

I'll begin by laying out some some ideas that are considered true for the sake of argument: 1. Given: God Exists 2. Given: God is Perfect 3. Given: Everything God does is good 4. Given: Everything ...
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1answer
62 views

Why is the darapti syllogism invalid?

I found the following exposition of darapti on wikipedia: All squares are rectangles. (MaP) All squares are rhombuses. (MaS) ∴ Some rhombuses are rectangles. (SiP) As far as I can see, this is ...
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1answer
54 views

Modal logic and Boolean algebras

Is there an intrinsic, hidden modal logic within ordinary (abstract) Boolean algebras? I do not question whether interior or closure algebras are Boolean algebras. Nor do I seek for an explanation of ...
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4answers
109 views

“This sentence is true”. Is there a word for this class of statement?

Is there a term that means "A self referential statement which is true if (and because) it is true and false if (and because) it is false"? "This sentence is a lie" is a paradox in the sense of ...
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0answers
109 views

Why killing/death is more accepted (morally) than nudity on television/movies? [closed]

Is there any logic why killing/death is more accepted (morally) on television rather than nudity/sex? It seems like a paradox to me the fact that all the laws (in the Occident) have severe punishment ...
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2answers
132 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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37 views

Philosophically (through logic and reason) how does one get to liberty, freedom, destiny from positivism--raw science?

Auguste Comte was so 'positive' that there could be no metaphysical system, no explanation of essences (no need for such in an 'enlightened' age). He thought citizens should be trained only to look ...
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2answers
57 views

How does negation operate in modal logic?

I was mulling over this proposition: Just because something is provable doesn't mean that it is important; and wanted to consider its contrapositive. How would I write this in formal (modal) logic? ...
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3answers
150 views

Help with a proof in CSL

Premise: (A implies B) implies C Conclusion: (C implies A) implies A I had a logic exam a few hours ago, and this was one of the problems, but I really didn't know where to start. Since the ...
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3answers
60 views

Is the following statement a fallacy?

You only X because you Y. (with Y being true!) Example: Paul only defends the drug decriminalization because he has never been aggressed by a drug addict. Is this a fallacy? If not, how can we ...
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1answer
39 views

Counter argument to Nozick's counter to principle of fairness

Are there any strong counter arguments of Nozick's counter argument to principle of fairness. Nozick argues that although people may receive the benefits from the state, it does not mean the people ...
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1answer
48 views

Is the phrase “logic and reason” grammatically correct?

I have always interpreted logic to mean a systematic form (premise-reason-conclusion) of reason. So it seems that you are saying one word (reason) and a branch of that word (logic). But the "and" ...
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4answers
135 views

Is it an ad hominem attack to call somebody a troll?

Case 1: Person A criticizes person B. Person B says "We shouldn't feed the trolls. Best not to engage." Case 2: Person A voices their opinion on an issue being discussed on the forum. Person B says ...
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3answers
650 views

Should I learn logic before learning philosophy?

I read this question (this is the most relevant I found) with the answers however I still don't have the answers to my questions. I started reading the first lines of some philosophy books, I ...
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2answers
148 views

What kinds of logic or philosophy to improve comprehension of difficult writing?

In this post, the answer uses some logic to simplify a convoluted sentence. What's that kind of logic called? What other branches of logic or philosophy should I self-study in order to help ...
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1answer
54 views

Transitive Incompleteness of Logical WFF's Due to Godel's Incompleteness Theorem

If a set of theorems, or wff's, are used in conjunction with one another, does this have an impact on their completeness in terms of soundness? For example, I have five theorems of logic, or ...