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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167 views

How and why is this an equivocation (logical fallacy)?

I tried this reference, but don't perceive the following, at 60%-way down this page: "Nothing is better than" Margarine is better than nothing. Nothing is better than butter. ...
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0answers
33 views

Why does human logic change with rate of change? [on hold]

For example, if taxes rose by 10 percent next year people would be outraged and go crazy. But, if taxes were to rise slowly to that amount, there would be far less upheaval. Another example is gas ...
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1answer
38 views

Why is this an appeal to pity? Is it truly a fallacy?

I tried http://en.wikipedia.org/wiki/Appeal_to_pity. I kmow I flunked every exam, but if I don't pass this course, I'll have to retake it in summer school. You have to let me pass! Why is this ...
4
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2answers
102 views

Logical consequence and material conditional - Are they the same?

I'm taking basic discrete math course which includes basic intuitive introduction to logic (only things like statements, tautology truth tables, etc.). During the learning, I've wondered what is the ...
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44 views

What kinds of philosophy are described by these questions? How to self-learn them?

Is there a formal branch or name for the kind(s) of philosophy needed to answer questions like the following ? If so, how can I self-learn it? I stress that no legal knowledge is required. The ...
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0answers
31 views

How to self-learn legal arguments, logic, and reasoning?

What are some readable, eloquent (without legalese) books on arguments, fallacies, logic, and reasoning, as applied and used in law? This question is aimed towards a greenhorn/tenderfoot with ...
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1answer
58 views

Why do we have a problem about understanding the concept of the “empty set”?

   The title seems quite bit more generalized, but I'm saying about the philosophers and mathematicians in the past who discussed about the concept of nothing, or the empty set. I'm ...
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3answers
111 views

Is noise necessary so as to have music?

Granted the following assumptions: Music can be thought of as a string of sounds. Noise can also be thought of as a string of sounds. Every sequence of sounds can be considered music. Would the ...
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3answers
88 views

Is this an Ad Hominem attack?

"I can only deduce that if you spout pro-palestinian rhetoric, and ignore that they are the initial aggressor because you aren't concerned with that truth, and you site Youtube as your source (as ...
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0answers
45 views

Marc Lange's stability concept of laws of nature: how do disjunctive antecedents work?

Dear philosophizing community! I'm an ecology student who's dabbling into philosophy of science. I'm currently writing a term paper on laws of nature (with a focus on ecology as a special science) ...
5
votes
5answers
177 views

Is C.S. Lewis argument for absolute morality valid?

I just stumbled on this argument from a Christian website that claims it is from C.S. Lewis' Mere Christianity: The moment you say that one set of moral ideas can be better than another, you are, ...
6
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1answer
39 views

Supervaluationism and Theories of Truth

How does the supervaluationalist defend his/her theory of truth since the correspondence theory of truth seems to presuppose bivalence? It would seem then that the only truth is Super-Truth. And, the ...
3
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2answers
68 views

How does abstraction/generalization in mathematics fit into inductive reasoning?

I have a question about the nature of generalization and abstraction. Human reasoning is commonly split up into two categories: deductive and inductive reasoning. Are all instances of generalization ...
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2answers
60 views

Material Conditional Not Logically Equivalent?

Hi all this is my first time using this site so I hope I am presenting this properly, apologies if not. It is said that “a → b” and “¬(a and ¬ b)” are logically equivalent but I do not understand ...
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1answer
65 views

Estimating the “goodness” of a proposition [closed]

I am a software developer who is studying mathematics and logic. I made this proposition, I wanted to see how good it is, from your perspective as experts. It is not actually known whether ...
2
votes
1answer
42 views

Why is Tarski's semantic theory of truth formally correct and materially adequate?

In "The Semantic Conception of Truth and the Foundations of Semantics" (1944) Alfred Tarski asserts that a satisfactory definition of truth must be both formally correct and materially adequate. A ...
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2answers
49 views

Are there any comprehensive undergrad level philosophy books about definitions?

Although I believe that I now have some vague idea about what the fundamental subject matter of philosophy presumably concerns, I (nevertheless) still occasionally come across philosophical writings ...
5
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3answers
95 views

Why is “unless” considered a conditional/disjunction rather than an equivalence/exclusive or?

The English connective "unless" is commonly considered a conditional or a disjunction (which are really the same thing with some slight re-arrangements and "not"s). Here is an example. Quoting that ...
5
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3answers
138 views

Is there such a thing as a 'necessary truth'?

Wikipedia (note the redirect) defines 'necessary truth' as statements which "could not be untrue", and I assume that this is how the term is usually used. A search through the SEP shows that while ...
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3answers
71 views

Does racism towards racists count as racism? [closed]

I'm not good at giving examples (at this moment), but I think you can understand what I mean.
3
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1answer
66 views

What is the relation between the material conditional in logic and conditionals that we use every day?

The material conditional has a truth-value of T in every case except where the antecedent proposition is true and the consequent is false. However, this means that many conditionals are true (if only ...
4
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1answer
46 views

Should ever one ought to believe a proposition that he *knows* to be false?

Has this question ever been discussed in the philosophical literature? An example that comes to mind is a proposition like "I am the best chess player in the world" during a chess match. Arguably, ...
3
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0answers
35 views

Which ontological commitments are embedded in a straightforward Turing machine model?

Let's assume that in response to a question or problem, a certain type of idealized finite Turing machine can be presented as an answer as if it would really (=physically) exist. Is the corresponding ...
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1answer
59 views

Making Vacuous Material Conditionals False

What would be some of the implications of deciding that vacuous material conditionals should be rendered as false? For example, what would happen if we decided that conditionals like "If John squares ...
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0answers
28 views

Concrete Examples of Complex Term Analysis Using Predicate Logic

In all of my textbooks, there are no concrete case studies of how one can use predicate logic to analyze specific characteristics of complex terms. I am therefore looking for an exemplar for the ...
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0answers
33 views

Why does everything exist? [duplicate]

Why does everything exist? By everything, I mean each and every atom in each and every place in the complete universe. What would have been the problem if the whole of universe didn't exist? What is ...
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1answer
43 views

Help with simple deductive proof

I am taking a class on natural deduction for the first time and we are currently on deductive proofs, I am having trouble with this one: Premise: A Premise: [(A&B) or (C&D)] Conclusion: not ...
2
votes
1answer
46 views

Help with a modal Hilbert-style proof of (□(a>b)&◊(a&c))>◊(b&c)

Can't grasp how it can be proved. To proof just propositional calculus formula (without modal operators) at first seems rather natural to me. Tried the law of importation scheme but it didn't work ...
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votes
3answers
92 views

Asked to analyse a contradictory quote that I don't agree with [closed]

I'm given a quote If you don't like something, change it. If you can't change it, change your attitude". The statement is to discuss how this idea was developed with respect to the two ...
4
votes
5answers
172 views

Justify Occam's Razor

I'm aware of a few justifications for Occam's (or Ockham) Razor, as it's usually understood that extra factors/complexities should not be added unnecessarily. The only truly compelling justification I ...
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0answers
31 views

Belnaps four-valued relevance logic

Belnap, the American Logician, constructed a four-valued logic which is a form of relavance logic; interestingly the truth-values it takes are: true false both true & false neither ...
8
votes
7answers
570 views

How fundamental is logic?

I had always perceived logic as something that exists outside mathematics, physics/the physical, human consciousness, and everything. So when someone in my class posed the question whether logic can ...
1
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1answer
54 views

The Truth-Falsehood Dichotomy and Logic

Some philosophers argue against truth bivalency, and say that not every statement must be true or false, but some statements can be untrue without being false, or truth-ambiguous, or both true and ...
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2answers
61 views

How should we understand the oracle's dilemma in making a prediction?

Let's look at a thought experiment: There is an oracle who has exact knowledge of the state of a deterministic universe, so her predictions about the universe's future have always turned out to be ...
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1answer
31 views

Anti-Realism about Higher-Order Vagueness

Who are the main anti-realists about higher-order vagueness? Would Crispin Wright be one? And, if so, is he a universal or partial anti-realist?
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0answers
35 views

Object language versus Metalanguage

I am doing some research on metalanguage with respect to mathematical logic and I have become a little confused about the relationship between an object language and the metalanguage that is used to ...
0
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1answer
35 views

Do sentences that are “selection violations” have truth values?

Given a grammatical sentence like "Colorless green grass sleeps furiously" is it possible to assign a truth value to it?
11
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8answers
2k views

Why can't humans believe contradictions?

I'm reading something on the topic of logic and one of the exercises asked me to convince myself that a contradictory statement was true. I could not convince myself of this and now I am curious about ...
4
votes
1answer
46 views

Why do Conditional Semantics matter?

It seems that in most everyday cases, taking conditionals to have material truth conditions suffices for us to reason with them correctly (in the sense that using material truth conditions will most ...
1
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2answers
62 views

What is the relationship of “if A then B” and “A only if B”?

Consider the following, "if A then B" implies "A only if B". For example, take "if it is raining, the sidewalk will be wet,". Therefore, "it is raining only if the sidewalk is wet." The first ...
5
votes
4answers
62 views

Does the problem of “Underspecified Conditional Antecedents” imply that many (uttered) conditionals are false?

Suppose m is a dry match. Under most circumstances, if m is struck, it will light. But if somebody were to wet m, then we might stipulate that m would not light even if it were struck. Suppose S ...
8
votes
8answers
229 views

Would it be good if everyone was good?

When people meet somebody who hurts us or just behaves in an inappropriate way, we usually think that the world would be so wonderful if all people were good. I know that one can have his own ...
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votes
3answers
102 views

Thought experiment: Argument whose life is more valuable organic or mechanical? [closed]

Let's consider the following scenario: There is a really important mission consisting of a team of two individuals: a sentient, artificially intelligent robot and a human. If the mission fails, ...
4
votes
3answers
83 views

Could a scientific unification theory and scientific method itself be misleading?

I aspire to one day be a scientist (specifically an astrophysicist) and I have been reading up on many novels (like those of Asimov) which look into the development of humanity. I know that our ...
1
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0answers
62 views

What is the Difference between Vagueness and Indeterminacy?

Is "There will be a sea battle tomorrow" a borderline case of vagueness? Or, is it a case of modal indeterminacy? Or both? Where do we draw the line between the two? And ,what about "There is a sea ...
3
votes
0answers
21 views

Chrysippus and Strict Implicature

In A History of Ancient Philosophy, Karsten Friis Johansen claims that Chrysippus offers a theory of truth for conditionals that is a version of strict implicature and intensional semantics. However, ...
3
votes
1answer
56 views

Why do the Stoics Matter?

Aside from overcoming the Fallacy of Four Terms, what were the major contributions of Stoic syllogisms? What did they provide that Aristotelian syllogisms could not? And, what were their major ...
2
votes
1answer
52 views

Is there canonical terminology for logical connectives between more than two propositions?

My problem is with the definition of exclusive disjunction, at least according to Wikipedia. The Wikipedia page for Exclusive Or, at the time of writing, states that "More generally, XOR is true ...
3
votes
1answer
36 views

Who were the major innovators of new types of syllogisms?

Who were the major innovators of new kinds of syllogisms (i.e. introduced disjunctive syllogisms, etc) in the ancient and medieval periods aside from Aristotle, Theophrastus, the Stoics, and ...
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1answer
140 views

Why statement “either ”X is false“ or ”X is not false“” is not correct?

Please help me to understand the following confusing reasoning: According to laws of logic either "X is false" or "X is not false". Let's call the statement1. Let's consider well known statement ...