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 any relation beetwen justification logic and type theory?

Justification logics, was introduced by Sergei Artemov, are epistemic logics which allow knowledge and belief modalities to be ‘unfolded’ into justification terms: instead of □X one writes t:X, and ...
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37 views

Consciousness and its relationship to Category Theory [on hold]

Since consciousness is implicitly understood/used in the use of categories , could we consider it a "fundamental" functor ? Category Theory is very general (covering/useful) to many fields now ...
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5answers
63 views

Is fence sitting ever admirable and valuable?

This quote is from a website for an undergraduate law admissions test of 40 minutes: Don’t sit on the fence. Don’t say that each side in an argument has a point unless you go on to say which point ...
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1answer
149 views

How is First Order Logic complete but not decidable?

Why doesn't completeness imply decidability for first order logic? First order logic is complete, which means (I think) given a set of sentences A and a sentence B, then either B or ~B can be arrived ...
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2answers
50 views

What is water (or any common noun)? [on hold]

What does the term "water" refer to? It can't be any particular H2O molecule, so is it simply the set of all H2O molecules? As you can see, my question is not really about water.
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3answers
50 views

Can political ideologies be logically undecidable? If so, what are the consequences of this?

I'm having a thought that I would like more expert opinion on, as this crosses boundaries between philosophical logic and political science. My premise is that a political ideology can be represented ...
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1answer
88 views

Are there real paradoxes?

Paradoxes arise in mathematics; a famous one being Russells; usually its taken as a sign that the theoretical ediface needs to change. The difficult question is how; for example Russell developed his ...
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1answer
19 views

Is a loaded question a fallacy?

http://en.wikipedia.org/wiki/Loaded_question says that a loaded question = a complex question fallacy. Yet how's it a fallacy? Isn't it a logically consistent, valid (yet militant and treacherous) ...
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1answer
17 views

What are the axioms for quantified modal logic?

The plainest vanilla variety of propositional modal logic introduces two operators <> which is possibility, and [] which is neccessity. The axioms are: ◊p iff ¬□¬p □p iff ¬◊¬p What is ...
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5answers
63 views

Can there be cause and effect without time?

Our usual understanding of cause and effect operates tensely; that is in time. But consider a basic statement in some generic computer language: if x then y Is this in time? Well an actually ...
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2answers
67 views

'No one would go to Hitler’s funeral if he was alive today’

‘No one would go to Hitler’s funeral if he was alive today’ – Ron Brown MP, demonstrating a weakness in logic. Source: p 191, How the Law Works, Gary Slapper Sadly, the author didn't explain ...
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2answers
64 views

Help understanding logical fallacies in this statment

I'm trying to understand the arguments and logic that make up the three statements statements below (taken from the graphic novel Persepolis as the government's arguments for making women covering ...
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5answers
596 views

Why are homologies evidence for evolution instead of common design?

I have seen some creationists arguing that when evolutionary biologists use homologies (anatomical or genetic) as evidence for evolution, they are committing the fallacy of affirming the consequent. ...
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1answer
63 views

What if what is possible follows from logic alone

Suppose that every imaginative variation [I don't mean this in any technical sense] of what is physically possible is necessarily possible: because what I can imagine follows from logic alone. ...
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21 views

Why isn't conceptual analysis considered part of logic?

The question is in the title. Much of mathematics is unpackaging definitions and using the principle of substitution to come to results about identities (among other things). This to me feels very ...
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3answers
98 views

Is there any reason for the heavy focus on binary relations in formal logic?

As a fan of C. S. Peirce, I'm surprised that, at least triadic relations, aren't investigated as much as binary relations are. What I mean is that with binary relations, they have already been ...
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1answer
45 views

Do two moral values exist, such that both imply the other?

Two moral values exist, such that one implies the other. Example: "One should be nice" -> "One should not kill". Do two moral values exist, such that both imply the other? Would two such moral values ...
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1answer
76 views

If modality across some domain was such that anything is possible, then does modal logic entail that everything actual is necessary?

If modality across some domain was such that anything is possible, then does modal logic entail that everything actual is necessary? It seems intuitive that would be the case.
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44 views

The logic of indefinable variables [closed]

Suppose that I cannot see the limit of what I am able to see. Interpreting the Tractatus when it says: our visual field has no limits It does seem that I can see the edge of things that I see ...
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52 views

Logic regarding conclusions

What is the difference between a conclusion that is "necessarily true, but not false" vs. "necessarily false, but not true"? They seem the same to me or is the answer based on probability? In the ...
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1answer
50 views

Can anyone correct my understanding of “a priori conception”

Not only in judgements, however, but even in conceptions, is an a priori origin manifest. For example, if we take away by degrees from our conceptions of a body all that can be referred to mere ...
3
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1answer
25 views

What is an epistemic norm?

What is the definition of an epistemic norm? In what ways does it differ from a consistency norm or a rationality norm? Specifically, are epistemic norms a superset of rationality norms? EDIT: ...
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3answers
102 views

Is it possible to be truly unbiased?

I was pondering this question: Inductive Argument Against Believing Anything I his argument, the OP suggests that, in the position of choosing a system of belief where there are multiple, large ...
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3answers
89 views

How are rules of inference established as valid?

I'm curious as to how rules of inference are established. Is this an empirical act? For example if I know the premises "If I jump, then I fall" and "I jump" is it truly valid to conclude that "I ...
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3answers
115 views

What exactly is informal logic and is this what I'm looking for?

I've been reading and researching about formal and symbolic logic for some time now, mainly out of interest in rationality. But I've come to a point where the various logical systems seem more like ...
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127 views

Does this argument involving the Law of Identity equate to Essentialism?

Does the following entail Essentialism? Being obeys the Law of identity A necessary entity is necessarily its predicate The subject in a predication is what the being of the entity they make is ...
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14answers
429 views

Inductive Argument Against Believing Anything

I don't understand why I should believe my own conclusions. Let's take the metaphysical question of whether God exists (just as an example). There are, and have been throughout history, billions of ...
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1answer
44 views

Preservation of theoreticity under union

I'm working through various presentations of Henkin-style completeness proofs for first-order logic, where the underlying first-order language need not be countable. I understand most of the ...
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2answers
102 views

Functions vs Relations [closed]

Okay, so I was not introduced to functions in my elementary logic textbook. But they appeared in my mathematical logic textbook. I noticed that in statements like 1 + 2, + is called a function ...
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1answer
63 views

Logical Form of an Appeal to Probability

How can you express an "Appeal to Probability" argument in a logical notation? Feel free to use any forms or renditions of logic, including APL, as I know there are different symbols that can be used. ...
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0answers
39 views

Why Bad Things (Habits/Pessimism) prevails automatically,But Good Things(Optimism) wont be adhered even if induced? [closed]

Good Habits are not adhered to our routines even if practised where as Bad Habits are too much attractive implicitly without any effort. Why? Here, Please dont simply Divide Good & Bad Habits are ...
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6answers
247 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
38 views

Why does human logic change with rate of change? [closed]

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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2answers
73 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 ...
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2answers
120 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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1answer
75 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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1answer
61 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
77 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
122 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
103 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
58 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) ...
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5answers
190 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
41 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
80 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
65 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
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1answer
55 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
53 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 ...
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105 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 ...
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3answers
148 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 ...