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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When an individual makes a discovery

When an individual, or society as a whole, makes a discovery, different outcomes can occur eg: they can enrich the individual OR they can debilitate the individual OR they can confront the ...
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270 views

How is that possible? [on hold]

"Last Word" game rating 172.62% ?
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28 views

When a fallacy actually occurs

Assume a debate has occurred and a result ended the debate, but in this result a slippery slope is coming true - more specifically the contrapositive used as a basis for argument that relied on a ...
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3answers
64 views

Argument against democracy/socialism as an ethical system [on hold]

If n=4 people showed up and told you, "we're going to take our combined wages and vote about what to do with half of it", most people would consider it theft at best. Even in theory, I can't imagine ...
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19 views

What and how does 'modus tollens' deny? [closed]

I already understand, and so ask NOT about, the concept of modus tollens. Instead, I wish to ask whether its Latin etymology relates to its modern definition. If only indirectly, then please expose ...
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1answer
90 views

Handling “paradoxes” in logic: The sentence after this is true. The sentence before this is false

My favorite paradox that leads to an endless regress, and also leads to a question: The sentence after this is true. The sentence before this is false When contradictions appear in proofs, ...
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1answer
26 views

“Don't do what I tell you not to do” - what to do if you always do the opposite? [duplicate]

I'm not sure if philosophy is the right topic for this, but it's logic and language, so it kind of matches. Me and my friend played a little game this morning where I said "don't do this and that" ...
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3answers
131 views

What are the important effects of studying logic?

I'm working on my assignment in Logic and I'm having a hard time answering this question maybe because my insights about the subject isn't enough because we're just getting started, So can you please ...
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3answers
151 views

How does infinity of numbers and of space work?

Is infinity just continuous generation of numbers, or can space be actually infinite? If it is finite can we see it expand if we went to the edge? When I say "I am counting to infinity" does it mean ...
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3answers
88 views

How to interpret “it is possible that x is impossible”?

The question is about the logical form of the sentence, x can be any object or process, actual infinity, tachyon, philosophical zombie, telepathy, etc. To conclude that x is impossible we are supposed ...
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2answers
57 views

What is the term used for logic statements which are non reversible?

Something along the lines of If A then B, if B then not. A has to be true before B can be true but if B is true first then A isn't true. Is there a term describing this in logic or philosophy?
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1answer
36 views

What is the connection between temporal and epistemic knowledge?

Recently I read all kinds of work from logic scientists in which epistemic logic was the main topic. Where epistmic change refers to change in knowledge of some agent in a multi-agent system (in a ...
3
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3answers
98 views

Why Continue Using Logic Symbology and Truth Tables

With the advent of computers and the creation and adoption of so many computer programming languages, are logic symbols still valuable or are they a relic of the past? If logic symbology remains ...
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1answer
64 views

What is the “simple logical truth” that makes omniscience self-contradictory?

Patrick Grim claims in "Problems with Omniscience" that there is a "simple truth well established as a logical theorem", which shows that omniscience is a contradictory concept. I am failing to see ...
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2answers
54 views

Does “the experience of transition requires negotiation between sacrifice and opportunity” make sense logically? [closed]

I've thought about this statement enough to know it doesn't make logical sense, but I've not thought hard enough to determine why it doesn't make logical sense. The word 'and' conceptually links two ...
6
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2answers
329 views

Is Socrates wrong in 'Euthyphro'?

I'm trying to understand 'Euthyphro', a popular book by Plato about Socrates. I believe I'm understanding what Socrates is saying; however I do not think it is correct. Referring to 10d to 11b ...
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2answers
90 views

Logical sentence… or not?

The following sentence, which is part of a presentation of the doctrine of structural holism and is translated from the french, does not seem quite to make sense to me: "each one [of the members of a ...
2
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1answer
58 views

Is there a suppressed premise in Anselm's Ontological Argument?

Source: 5 minutes 20 seconds juncture; Lecture 1, Video 4 (transcription); MITx: 24.00x Introduction to Philosophy; by MIT Associate Prof Caspar Hare PhD (Princeton) [...] Suppose God existed in ...
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1answer
50 views

Interpretation of implication symbol in modal logic

Suppose we have two propositions p and q, and an implication of this form: p → □q I can think of two potential interpretations of the meaning of this in terms of possible worlds: If p is true in ...
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1answer
84 views

Definition of “proof”

I read a book of logical puzzles once and there was a little story in it (fictional) about some boy who received an F on his geometry test because his professor said his proof that all angles of a ...
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3answers
131 views

Argument infinite regression problem about “why we should go vegan”

It should be familiar that some groups, particularly animal rights groups have always been trying to pursue others to go vegan One of the argument goes like this: "Animals want to live, and they ...
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3answers
85 views

How to deal with counterfactuals with false antecedents

Consider the following hypothetical question: If there were two moons, what kind of poem would be composed? There are two ways of considering this type of statement that I find unexciting: Any ...
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2answers
70 views

“None of the tall people are rich. Joe is rich, therefore Joe isn't tall.” Is this valid?

I've thought about it into two ways but I don't know if either, neither or bow are correct: First using sets: Given the sets "T" (tall people) y "R"(rich people), for Joe to be tall and rich, Joe has ...
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2answers
118 views

How to define a number [closed]

What is the positive real number (say less than one) that is not a rational nor an irrational number? I have encountered a mathematical problem that confused me about the definition of real ...
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3answers
49 views

Symbol to denote a credulous consequence

I have been trying to find the correct symbol to denote a credulous consequence. I've only been successful in finding the symbol for skeptical consequence, does a symbol for credulous consequence ...
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1answer
33 views

A form of appealing to nature?

I'm wondering if you could say that this is a from of the Natural fallacy: Example 1: Evolution has made us omnivorous, therefore eating meat is correct. Example 2: Animals eat animals, I'm an ...
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3answers
175 views

What's the logical fallacy called when people somehow equate the rate of something to the actual value of something?

Above, taken from conservapedia, is arguing that Swedes are dropping in intelligence, but is instead trying to imply that Swedes are stupid. (They can't pull together a real argument that Swedes are ...
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2answers
129 views

Are there any work around after Godel's incompleteness theorems?

It seems to me that mathematicians or computer science theorists are still trying to come up a proof for conjecture they made in first or second order logic. By Godel's incompleteness theorems there ...
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10answers
190 views

Is it possible that our world had no beginning but is rather eternal?

Is there any logical reason that our world or rather existence of any sort should have a beginning? In other words does the assumption of 'eternal' existence create any contradictions?
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1answer
67 views

How to simplify: Unless, if A, B, then C

This ELU question motivated the following, but I abbreviate all clauses. Also, lest 'then' be written twice in the same sequence of events, interpret the adverb 'then' to precede the adverb 'thence'. ...
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2answers
66 views

What does 1 John, 4:19. imply?

1 John 4:19 , "so you see, our love for Him comes as a result of His loving us first." Does the above Biblical Scripture imply through Modus Tollens what I think it does? That is, If God loved us ...
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2answers
39 views

Concerning the logical projection: How to express nullary and unary operations as binary operations?

Let P and Q be two statements, where P has truth table (T,T,F,F) and Q has truth table (T,F,T,F). As you might know, there are exactly 16 different truth tables of the form (w,x,y,z), all of which ...
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2answers
72 views

Causality vs. implication

Implication is said to be more general than causality since, for example, being a dog implies being a mammal but it doesn't cause it. Is there a formalization of the difference between implication and ...
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1answer
44 views

Are there Decision Trees for Identifying Fallacies?

Question 1: What is the recommended methodology for identifying specific fallacies? Is there a "Decision Tree", or some other helpful approach? Question 2: Or, at the very least, are there ...
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3answers
65 views

Name of Formal Fallacy? Probability does not entail Certainty

Question 1: What is the name of the Formal Fallacy wherein a Deductive Conclusion is arrived at via the course of an Inductive Argument--which reduces the certainty of its own conclusion? ...
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5answers
125 views

Negation of an “at least” statement

Consider the statement At least two of my library books are overdue. I am trying to understand what the negation of this statement would be. I have a couple guesses: Less than two of my ...
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1answer
59 views

Identify the type of fallacy

'Giving charity to young healthy beggars is wrong. Thus, charity is a wrong policy.' Is this a fallacy of converse accident or of composition?
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164 views

Asymmetries in two opposite arguments from ignorance

Joe claims: "There is no proof that unicorn exist, therefore unicorns do not exist". Alice claims: "There is no proof that unicorns do not exist, therefore unicorns exist". Bob claims: "There is no ...
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3answers
129 views

Should scientific theories be self-consistent?

Bridgeman writes in A Physicist's Second Reaction to Mengenlehre:"The feeling that actually existing things are not self-contradictory is so elemental as to almost constitute a definition of what we ...
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2answers
123 views

What's a good source for refreshing my formal logic skills prior to graduate school?

I need to flex my formal logic muscles prior to graduate school--I've had a dry spell in my logic practices while finishing my mathematics degree, particularly since the logic used in analysis, ...
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3answers
280 views

Propositions that are always true, but aren't tautologies?

Consider the following statements: "Snow melts during the day in the Sahara" "A human will die without oxygen" "Photons have no rest mass" These are statements that are always true, not ...
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2answers
167 views

What are the practical applications of modal logic?

I'm a computer science and philosophy double major. I know logic is paramount in computer science, but what about modal logic? Are there any practical applications in computer science and perhaps even ...
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1answer
60 views

Does the slippery slope fallacy have any usage outside of formal logic?

I already searched for this but it doesn't really contain what I'm about to ask. The slippery slope fallacy, according to Wikipedia's definition, is "a logical device, but it is usually known under ...
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54 views

How do we know something is a “category mistake”?

I believe that Gilbert Ryle introduced the term "category mistake", but I am struggling to apply the term. Could you please give me an obvious and less obvious instance of a category-mistake? And if ...
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1answer
54 views

How to work with a premise containing multiple 'if' s?

This was alleged erroneous; so please explain as though I were 10 years old. See the bolded in the following. 3 and 4 confuse me because they are premises, but they themselves are conditional ...
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1answer
83 views

Is cognitivism compatible with moral anti-realism?

According to my professor, Sharon Street is both a cognitivist and a moral anti-realist. I can't seem to reconcile with that. How can you form a propositional statement about something that doesn't ...
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4answers
96 views

How would you translate the sentence “Some philosophers love all philosophers, only if they love themselves”

I have it as: ((x)(Px&Lxx))>(($y)(x)(Py&(Pz>Lyz)) Where P is a philosopher L is loves (Predicate logic)
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1answer
51 views

Why is most modal logic about necessity vs possibility rather than permission or wishes?

It seems to me that the notions of modal logic are all shaped primarily by one modal, 'can/must' (konnen/mussen). Has anyone looked at all deeply at how this convention compares with the other common ...
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2answers
43 views

If G is absent whenever F is absent, then F is a sufficient condition for G

True or false and why? I am very confused on this topic: If G is absent whenever F is absent, then F is a sufficient condition for G. I know that if F is a sufficient condition for G then F ...
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3answers
98 views

What is the logical form of a question?

A common thread in Analytic philosophy, starting with Frege, and through Russell, Wittgenstein and the Logical Positivists, is that there is an ideal and purely logical language, with which we can ...