Questions tagged [propositions]
76 questions
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What is the truth value of the proposition 'All unicorns are beautiful'?
If we let Fx denotes that which has the property of being a unicorn, and Gx denotes that which has the property of being beautiful, then this proposition would be signified by the following:
∀x(Fx→Gx)
Obviously, we know unicorns don't exist, so this…
Constantly confused
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Shouldn't statements be considered equivalent based on their meaning rather than truth tables?
Consider the following truth table, which serves to define the logical connective ⇔,
P | Q || P⇔Q
T | T || T
T | F || F
F | T || F
F | F || T
According to the above truth table, the logical connective ⇔ is defined as the binary operation which…
EthanAlvaree
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Existential import: in logic, do propositions default to true or false when objects in them do not exist?
In this hypothetical:
Firefighters always tell the truth, while politicians always tell lies.
Suppose three people, who are either a mix of firefighters and politicians, all politicians, or all firefighters, surround you and say "every politician in…
Josh
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Is the principle of non-contradiction self-evident?
The principle of non-contradiction is that contradictory propositions cannot both be true, e. g. the two propositions "A is B" and "A is not B" are mutually exclusive.
However, whenever something is used as a criterion for truth (like the principle…
user3776022
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Why are there so many different opinions of categorical propositions?
I'm reading into categorical propositions and there seems to be lots of different opinions on what they are, and what their existential import is.
Why are there so many different variations? Shouldn't Aristotle's original definitions be fine as they…
Richard Bamford
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Intuitively, why are Universal Statements true in the Empty Universe?
Source: p 165. Sweet Reason: A Field Guide to Modern Logic (2010 2 ed) by Henle, Garfield, Tymoczko.
I read this on Math SE; please advise if it pertains to my simpler question.
One property of the empty universe [hereafter EU] is that every…
user8572
5
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2 answers
Are contradictory propositions in the propositional logic still contradictory in the predicate logic?
There is one seeming issue I happened upon that bothers me to no end.
Take a proposition like “Snow is white”. “Snow is white” and its negation “Snow is not white” are obviously contradictory. However, when they are expressed in the predicate logic,…
Falcon
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How does one differentiate epistemological and ontological claims?
I'm taking an introductory philosophy course and I find it fascinating. I can't really figure out an assignment though because I'm a bit foggy on what the difference between ontological and epistemological claims is.
Of course, I'm writing 2-3…
Annie
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How does one judge "complexity" of assumptions for the purposes of "best explanation"?
The context for this question is from assessing theological arguments from the point of view of 'inference to the best explanation'.
In philosophy (and science), we may wish to argue that some hypothesis 'explains' some facts we observe. In which…
Joe Lee-Doktor
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Making 'sense' of Wittgenstein's senselessness / nonsense distinction in the Tractatus
For this question I'm just considering Wittgenstein's theory at the time of the Tractatus.
As far as I know, for Wittgenstein:
Meaning - The object denoted by a word (i.e. referent).
Sense - The conditions under which a sentence can be verified or…
M. Guillaume
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Are analytic propositions always vacuously true?
In a possible world where there are no bachelors is the proposition "bachelors are unmarried" vacuously true? Or is it tautologically true and you would then need to quantify bachelors as "all bachelors in this world are unmarried" to make it…
ApacheRosePeacock
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Truth-functional vs non-truth functional conditionals
I'm struggling to understand truth functionality.
I know that a connective is truth-functional if the truth value of a compound statement formed with that connective is completely determined by the truth values of the input…
user51462
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Can one have propositional knowledge without knowing the corresponding proposition?
The concept of propositional knowledge -- knowledge that one has through holding a justified belief in a proposition that states a fact -- is a foundational one in epistemology (for example, it is what the SEP entry on epistemology leads with.)…
A Raybould
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Definition of proposition
The term proposition has a broad use in contemporary philosophy. It is used to refer to some or all of the following: the primary bearers of truth-value, the objects of belief and other "propositional attitudes" (i.e., what is believed, doubted,…
LittleD
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Why isn't "I am Bill" a proposition?
In fleshing out the traditional definition of omniscience, William Lane Craig distinguishes between propositional knowledge and non-propositional knowledge, claiming that to be omniscient is to know every true proposition and not believe any false…
user20658
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