Questions tagged [logic]

For questions about logic, whether it concerns syllogistic logic, mathematical logic or the nature of logic itself.

Logic is the study of formal systems of reasoning, especially of the deductive variety. It is one of the fundamental philosophical subdisciplines.

The traditional approach to logic, starting with Aristotle, is syllogistic logic. The introduction of mathematical methods during the late 19th century and with it the formulation of first-order logic have resulted in a complete transformation of the field. This development allowed to raise and answer questions about the foundations of mathematics. During the second part of the 20th century many philosophical logics have been introduced in order to tackle many other questions in philosophy.

Key notions of logic are formal languages, proofs and truth.

3688 questions
169
votes
16 answers

Is 'guns don't kill people, people kill people' a good argument?

I'm hearing the argument X doesn't do Y people do Y in quite a few guises. For instance in it's original form guns don't kill people; people kill people Presumably, therefore guns are OK cars don't kill people; people kill people Again, the…
Crab Bucket
  • 2,852
  • 4
  • 20
  • 23
95
votes
14 answers

Is Kurt Gödel's Incompleteness Theorem a "cheap trick"?

I found a throw-away critique of Kurt Gödel's Incompleteness Theorem in an essay about Deconstruction: The basic enterprise of contemporary literary criticism is actually quite simple. It is based on the observation that with a sufficient amount…
80
votes
12 answers

Can you prove anything in philosophy?

I don't understand philosophy very well, and so I am wondering whether you can "prove" anything in philosophy. It always seems you can go a layer down, and find another question, almost endlessly until you get to the question of "why/how/are we…
John M.
  • 926
  • 1
  • 8
  • 11
68
votes
6 answers

Logical fallacy: X is bad, Y is worse, thus X is not bad

I have heard this type of argument too many times: You are criticising X using well researched facts and arguments. Your interlocutor, states that Y is much worse with equally well researched facts and arguments. X and Y are linked in a general…
62
votes
21 answers

Is the "omniscient-omnipotent-omnipresent" definition of God consistent?

God is commonly defined as an omniscient (infinite knowledge), omnipotent (unlimited power), omnipresent (present everywhere) entity. Is there any logical inconsistency in this definition? I have seen several paradoxes like below Does God know what…
AIB
  • 1,501
  • 1
  • 14
  • 17
51
votes
15 answers

Does Pascal's Wager contain any logical flaws or fallacies?

Blaise Pascal's famous wager was that even if the existence of God cannot be determined through reason, a rational person should wager as though God exists, because living life accordingly has everything to gain, and nothing to lose. What logical…
John Lyon
  • 764
  • 1
  • 6
  • 10
46
votes
10 answers

Why do I accept some inconsequential claims as "obviously true" without evidence? E.g. "Most people don't like to be hit on the head with a hammer."

There are certain claims that I accept as obviously true without (much) evidence. For example: Most people don't like to be hit on the head with a hammer. Donald Trump ate dinner some time last week. There has yet to be a whale on the moon. I…
Rebecca J. Stones
  • 891
  • 1
  • 7
  • 13
42
votes
16 answers

Does a negative claimant have a burden of proof?

I have often heard it said that the burden of proof is on the positive claimant but not on the one making a negative claim. A person claiming, "God exists" has a burden of proof but not a person claiming, "God does not exist." If I assert,…
user409
42
votes
10 answers

What fallacy in Pascal's Wager allows replacing God with the devil?

I wanted to know the name of the fallacy or fallacies the Pascal's Wager in the sense that it can be applied to motivate one's belief in many things. A similar argument to the original Wager can be used to say that it is prudent is to believe in the…
Barinder Singh
  • 1,298
  • 1
  • 13
  • 20
42
votes
16 answers

How to get started with philosophy without getting overwhelmed quickly?

I’ve spent a lot of time trying to find how to get started with philosophy but I can’t. It seems that getting started with computer programming is nothing in comparison - with computer programming it’s like: here are how if statements and for loops…
SBel
  • 529
  • 1
  • 5
  • 4
40
votes
13 answers

What are the necessary conditions for an action to be regarded as a free choice?

A common philosophical question revolves around the existence of free will, but what I've found is that these debates seem to gloss over the concept of "free will" itself, either taking it as a given that everyone understands what the term really…
Speldosa
  • 657
  • 5
  • 10
38
votes
13 answers

Is circular reasoning always a fallacy?

Suppose the following dialogue: ... "I accept only one notion of land property. Namely, 'I am doing my stuff here, therefore I am here". "But this means," he responded, "you can break into any place and stay there, using this rule." "There is…
rus9384
  • 2,536
  • 2
  • 13
  • 28
37
votes
10 answers

Is it a fallacy, and if so which, to believe we are special because our existence on Earth seems improbable?

People often use the argument that there must be a God, for example, because Earth and the laws of physics are perfectly situated for humans to exist the way we do. However, if Earth or even the universe as a whole were not situated so that life…
Tori
  • 473
  • 4
  • 4
35
votes
10 answers

Is it a fallacy if someone claims they need an explanation for every word of your argument to the point where they don't understand common terms?

Is it a fallacy if someone claims they need an explanation for every word of your argument to the point where they don't understand common terms? For example, suppose someone said, "If a dog bites people, then it's a vicious dog." Then someone…
dogperson
  • 351
  • 1
  • 3
  • 3
34
votes
6 answers

Three statements that contradict each other

In formal logic, it seems that a contradiction only arises between two statements. Is it possible to have a set of three statements that together are a contradiction, but where any two of the statements do not contradict each other?
Marc Bacvanski
  • 451
  • 4
  • 7
1
2 3
99 100