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Question concerning propositions

 
 
Reply Mon 4 Oct, 2010 06:21 am
I was told that propositions are the only things that can have truth or falsity. But what about statements? Going through my Logic textbook it defines statements "to be sentences that are either true or false", and that propositions are the "things expressed by statements". I am having, for some reason or another, an incredibly hard time understanding this. Does this mean that statements are also true and false as well as propositions? Or do the propositions express what the statements say?

Better still, what exactly is a proposition? My book states that they are what philosophers call "abstact entities" so they are not linguistic objects. They seem to be a priori (not entirely sure), but this really does not remove the difficulty I am having with what propositions are. Do propositions refer to the mere form of what is being expressed? Well anyway thats the difficulty I am having at the moment. Help from people who know a thing or two about Symbolic Logic would be nice.

Thank you.
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fresco
 
  1  
Reply Mon 4 Oct, 2010 08:15 am
@Ding an Sich,
Quote:
In logic and philosophy, the term proposition (from the word "proposal") refers to both (a) the "content" or "meaning" of a meaningful declarative sentence or (b) the pattern of symbols, marks, or sounds that make up a meaningful declarative sentence. The meaning of a proposition includes that it has the quality or property of being either true or false, and as such propositions are called truthbearers.
The existence of propositions in the abstract sense, as well as the existence of "meanings", is disputed by some philosophers. Where the concept of a "meaning" is admitted, its nature is controversial. In earlier texts writers have not always made it sufficiently clear whether they are using the term proposition in sense of the words or the "meaning" expressed by the words.[1] To avoid the controversies and ontological implications, the term sentence is often now used instead of proposition to refer to just those strings of symbols that are truthbearers, being either true or false under an interpretation. Strawson advocated the use of the term "statement", and this is the current usage in mathematical logic.
Wikipedia
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Owen phil
 
  1  
Reply Tue 5 Oct, 2010 02:55 am
@Ding an Sich,
Ding an Sich wrote:

I was told that propositions are the only things that can have truth or falsity. But what about statements? Going through my Logic textbook it defines statements "to be sentences that are either true or false", and that propositions are the "things expressed by statements". I am having, for some reason or another, an incredibly hard time understanding this. Does this mean that statements are also true and false as well as propositions? Or do the propositions express what the statements say?

Better still, what exactly is a proposition? My book states that they are what philosophers call "abstact entities" so they are not linguistic objects. They seem to be a priori (not entirely sure), but this really does not remove the difficulty I am having with what propositions are. Do propositions refer to the mere form of what is being expressed? Well anyway thats the difficulty I am having at the moment. Help from people who know a thing or two about Symbolic Logic would be nice.

Thank you.


imho...
Statements are declarative sentences.
Propositions are statements which are true or false.

All of: language, letters, words, sentences, statements, propositions, etc., are abstract entities.

Propositional logic only deals with 'declarative sentences which are either true or false' (propositions).

For example:
(this statement is true) -> (this statement is true), is not a WFF of propositional logic..because 'this statement is true' is not a proposition at all.
(this statement is true) is a sentence and it is a declarative sentence (statement) but it is not a proposition.
Ding an Sich
 
  1  
Reply Tue 5 Oct, 2010 01:29 pm
@Owen phil,
Owen phil wrote:

Ding an Sich wrote:

I was told that propositions are the only things that can have truth or falsity. But what about statements? Going through my Logic textbook it defines statements "to be sentences that are either true or false", and that propositions are the "things expressed by statements". I am having, for some reason or another, an incredibly hard time understanding this. Does this mean that statements are also true and false as well as propositions? Or do the propositions express what the statements say?

Better still, what exactly is a proposition? My book states that they are what philosophers call "abstact entities" so they are not linguistic objects. They seem to be a priori (not entirely sure), but this really does not remove the difficulty I am having with what propositions are. Do propositions refer to the mere form of what is being expressed? Well anyway thats the difficulty I am having at the moment. Help from people who know a thing or two about Symbolic Logic would be nice.

Thank you.


imho...
Statements are declarative sentences.
Propositions are statements which are true or false.

All of: language, letters, words, sentences, statements, propositions, etc., are abstract entities.

Propositional logic only deals with 'declarative sentences which are either true or false' (propositions).

For example:
(this statement is true) -> (this statement is true), is not a WFF of propositional logic..because 'this statement is true' is not a proposition at all.
(this statement is true) is a sentence and it is a declarative sentence (statement) but it is not a proposition.


Thanks for clearing that up. I do not know why I was having problems with this.
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