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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Is there a name or category for these misleading propositions?

Example I never lost in tennis against Roger Federer. It's a negation and 'true' but it's misleading. In fact I never played tennis against Federer. I'm looking for a name or a category for ...
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17 views

Is there a logic to formalize the concept of “understanding” [on hold]

The question may seem little bit weird given that philosophers have been struggling to have a full grasp on the concept of "understanding". But I'm wondering if there are any logics (modal-based or ...
2
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1answer
24 views

English Sentence to Logical Proposition Doubt

I am a newbie to Stack-Exchange and if there is any problem in my question -- I apologize beforehand . I was working my way through some Propositional Logic Questions in Discrete Maths by Rosen , ...
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1answer
43 views

Fungible Money Question

Suppose that there are two people, A and B. Each has a physical dollar bill. Each donates the dollar bill to an organization. The organization buys something for a dollar. First suppose that the ...
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3answers
74 views

Can you infer a house exists from the proposition “food cannot be found in any house”?

Give this statement "Food cannot be found in any house (in this area)" Can you correctly infer that "There is AT LEAST a house (in this area)"
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0answers
14 views

What is the purpose of winter bash? [migrated]

These kinds of activities are fun. Why do we do them? To bring joy to ourselves or the users?
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3answers
80 views

Is the science Physics allowed to ignore the rules of Philosophy of Science resp. the Scientific Method [on hold]

The Scientific Method in Science determines that premises, on which a theory is based, must be experimental verified, when possible. It is however possible that theories of the past are based on ...
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4answers
97 views

Why is it wrong to deduce determinism from a logical law?

In Aristotle's famous sea battle argument, he argues from bivalence (or something like it) to determinism. Stalnacker has an argument to determinism using standard logical laws, as well. My question ...
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1answer
43 views

Double arrow elimination

I know that P <=> Q becomes (p => q) ^ (q => p)using double arrow elimination but how about the following ? ~(P <=> Q) becoming ~(p => q) ^ ~(q => p) ? Also (~P <=> Q) ...
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2answers
130 views

Why does Aristotle suggest One is not a number?

Parmenides showed Nothing is not the same as Zero; the second is a number, and the first is not, in more than one sense; it also differs from the Buddhist notion of Sunyatta, which is nothing in a ...
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1answer
70 views

Predicate logic and quantifiers

Here are two sentences in Predicate Logic: For all x, there exists a y (If x is F, then x > y) For all x (If x is F, then there exists a y (x > y)) The difference is that in the first example, all ...
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1answer
55 views

If philosophical thought didn't existed? [on hold]

I am newly interested in philosophy. I am wandering, because of philosophy we got this far today (science, technology and human rights), but is it possible and what if the first men didn't start to ...
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1answer
30 views

Translate quantifiers into senstance

How can I translate the following into reasonable sentence ? You can let Rxyz stand for anything as long as it makes sense.
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4answers
161 views

Why is Internet anonymity important?

My grandfather just brought up the topic of requiring all communications on the Internet to be linked to an identity. His logic that all people should be held accountable for their actions is ...
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2answers
100 views

What average am I of the five people I spend most time with? [closed]

“You are the average of the five people you spend the most time with.” ― Jim Rohn This quote has been copied and pasted so many times I lost track. But, since I spend most (read: all) of my ...
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1answer
55 views

Is free will a third option aside from chance and necessity?

The determinism dilemma is that if our actions are predetermined they are not free, and if they are random they are not willed, either way there is no free will. Even if will causation is a mixture of ...
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3answers
48 views

Burden of proof

Who has the burden of proof when trying to prove or disprove someones religious beliefs? I have always believed it belongs to the person who is making a claim but can there be exceptions?
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1answer
38 views

Is arguing about “death sentence” in a dichotomic way a formal error? [closed]

Often people are trying to show that death sentence is good and useful, while some other are arguing to show the opposite. But reality is complex. If we would like to describe it with a mathematical ...
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2answers
53 views

Can someone identify the fallacy based on the below example?

I was talking to a small business owner the other day. When asked why they never incorporated in order to limit their liability, their explanation was, to paraphrase, "nothing bad has happened to us ...
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3answers
128 views

Predicate Logic (Natural deduction & transcription)

Taking an introductory logic course and we're now doing predicate logic instead of sentence logic. Sentence logic was easy for me but as for predicate...It's not really clicking for me just yet. There ...
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5answers
169 views

How to interpret an 'if' nested within another 'if'?

Source: p 153, Letters to a Law Student, 1 ed (2006), by McBride Section 2 of the Theft Act 1968 (title: “ ‘Dishonestly’ ”) provides that: (1) A person’s appropriation of property ...
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4answers
255 views

Is Galileo's argument about falling bodies logically flawed?

Galileo's famous argument against the Aristotle's theory of falling bodies goes like this. "Let's say heavy objects do fall faster than light ones. Then it seems the heavier weight will fall with the ...
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3answers
155 views

Does a statement exist which is its own proof?

In fake/pseudo mathematical notation: does there exist a statement S such that S = Proof(S)?
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2answers
64 views

How to give proof for Q ∧ R with the premisse ¬(¬¬¬P ∨ P)?

I'm trying to use fitch to get to an answer, but I'm really confused right now. Can someone help?
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12answers
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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 ...
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2answers
45 views

Can deontic conditionals be indicative? [on hold]

To check my understanding, the following is an indicative deontic conditional, correct? "If you live in Texas, you ought to watch football." It is indicative in the sense that it is reporting on ...
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1answer
55 views

Why happiness is induced by that which baffles us: What does laughter reveals about human nature? [closed]

I will attempt to be prompt. Variables/strings/operators: *The prime symbol (') will be used as an operator for an action's derivative [here, meaning antecedent] (e.g (eating a sandwich)' = ...
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1answer
35 views

Propositional Logic - Best Way to Translate Complex Legal Statutes

If one wanted to use standard propositional logic, what would be the most efficient way to translate a sentence from a natural language like: "Capital murder is the premeditated or non-premeditated ...
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1answer
39 views

birds of a feather flock together and guit by association

There is a saying "birds of a feather flock together" which usually boils down to People of similar character, background, or taste tend to congregate or associate with one another. Yet guilt by ...
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3answers
86 views

An argument is valid if the premises CANNOT all be true without the conclusion being true as well

"An argument is valid if the premises CANNOT all be true without the conclusion being true as well." Argument_1: P or Q. not Q. Therefore, P. Argument_1 is valid. Argument_2: B or M. M or C. ...
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4answers
144 views

What does the statement “Xs exist” really mean?

If someone were to claim: Xs exist. what do they actually mean? Do they mean: At least one X exists. or At least two Xs exist. In other words, does the phrase "Unicorns exist" mean "at ...
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3answers
148 views

How to prove the axiom is wrong?

The father of math (Euclid) wrote a book named Elements. The book is full of axioms and here are some of them I am interested in: Things equal to the same thing are also equal to one another. ...
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1answer
131 views

How do I use the “Barbara, Celarent, … etc.” mnemonic?

Medieval logicians memorized this most famous logic mnemonic: Barbara, Celarent, Darii, Ferio ← direct first figure Baralipton, Celantes, Dabitis, Fapesmo, Frisesomorum ← indirect first figure ...
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1answer
44 views

What kind of conditional does Nozick use in his theory of knowledge?

Knowledge is traditionally defined as justified true belief: in order for S to know P, S must believe P, P must be true, and S must be justified in believing P. Now this definition has been ...
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2answers
70 views

The Fallacy of Contraposition for Counterfactuals?

Example: 1.If Boris had gone (to the party), then O would still have gone. 2. Therefore, if O had not gone, then B would not have gone. Analysis: Suppose B wanted to go , but stayed away ... ...
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1answer
25 views

When are Counterfactuals transitive?

Analysis: For brevity, define 'gone' = 'gone to the party'. In this scenario, while it is true that had P gone, then A would have gone, and it is true that if A would have gone, then M would ...
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2answers
64 views

'If P were true' vs 'If P is the case'

Counterfactuals have this form: If [S:] P were true, Q would be true. Material conditional: If [P:] P is the case, then Q is the case. Counterfactuals are not material conditionals! [Does ...
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4answers
243 views

Can a “real” paradox exist?

Given a statement, S: "S is not true." We arrive at a paradoxical solution whether or not we assume S to be true or false. Does this automatically imply that we have made an error in logic, ...
2
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1answer
61 views

How to start studying philosophical logic?

As I'm planing to study Philosophical logic, I've some important questions. For example, I wonder: 1-Should I start with the algebraic approach? Should I start with another approach?(which one?) 2- ...
2
votes
1answer
53 views

How to discharge an assumption?

I am proving the follow argument [(A ↔ B ) → C] ⊢ [ - ( A ^ B) V C ] Using the following set of rules I, ^E, vI, vE, →I, →E, ↔I, ↔E, --E, -I Here are my steps but I got to the point where I ...
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1answer
29 views

What are the names, or arguments of the atomic sentence “Max ate a cake” and “I ate a cake.”

What are the names, or arguments of the atomic sentence Max ate a cake and I ate a cake. ? First of all, "Max" is definitely a name. But is "cake" a name? And in the second sentence, is ...
2
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1answer
73 views

Logical Consequence and Tarski's World

I found this question in an old exam paper. I have no idea what is expected from a question like this. Consider the Tarski's world below. This world illustrates that ¬∃xTet(x) is NOT a logical ...
2
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1answer
83 views

Help with a proof for the following arguments

I want to proof the following argument from both sides using the following rules ^I, ^E, vI, vE, →I, →E, ↔I, ↔E, --E, -I Argument [(A ↔ B ) → C] ⊢ [ - ( A ^ B) V C ] Please let me know ...
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2answers
222 views

Is it possible to provide a proof of the following arguments?

G & ¬ H ¬ H ⇒ H Therefore, S & I Is it possible to prove the validity of this argument without having any information of S or I in the premises? H ...
2
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5answers
78 views

Question regarding sound argument [duplicate]

Sound argument is an argument which is both valid and it's premises are true. But my question is, why do we mention in the definition of the sound argument that "it's premises are true" when we've ...
1
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1answer
55 views

Proof validity methods other than truth tables

I have read or heard some time ago that truth tables cannot be used to validate arguments which involves the use of quantifiers i.e. in predicate or quantificational logic where you can find ...
2
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4answers
153 views

Must infinity involve repetitions?

Infinity for Nietzsche in at least one line of argument involves the eternal return; he refers to it in the Die fröhliche Wissenschaft and Also sprach Zarathustra; most completely in his Notes on the ...
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2answers
66 views

Method to derive conclusions

Suppose, you have been given the following assumptions: 1. (W ⊃ (F ∨ M)) 2. ~F 3. (M ⊃ A) In what way you can come up with conclusion from this? What kind of inferences rules can be used here? I ...
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6answers
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Climate change statement - is there a logical fallacy here?

"97% of scientists agree that climate change is caused by humans - if 97% of scientists told you a plane was going to crash, would you get on it?" Arguments about the existence of climate change ...
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1answer
70 views

Did Wittgenstein say something about intuition for logic?

When one creates some logical content, like in programming, only naives think that this is a rational way of thinking. In fact, this is based on patterns and intuition. Did Wittgenstein say anything ...