4 definition by ceclark

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In logic, a fallacy is an incorrect conclusion. This may result in one of two ways.
1. If the structure of the argument is not correct at all, it is called a 'formal' fallacy. One, or both, of the first two propositions would be written incorrectly in relation to the other.
2. If the structure is correct in the first two propositions, but the conclusion is not put together properly, it is called an 'informal' fallacy.

The usual example of an argument that has no fallacy is:
Socrates is a man.
All men are mortal.
Therefore: Socrates is mortal.

Each sentence is a proposition. No propositions in an argument must be factually true to in order to create an argument with no fallacy; they must only follow the rules of logic. It is when the structure, the rules of logic, does not conform to the 256 various forms of a syllogism, it will contain a 'formal' fallacy. When only the conclusion does not follow the rules, it is an 'informal' fallacy.

Search for 'moods and figures of logic' for a full account of structure in logic.
1. It is a formal fallacy to say
Socrates is a man.
Dogs are mortal.
Therefore: Socrates is a dog. The second premise must contain either 'Socrates' or 'man' ('men), and in the right order. This is what is meant by the 'structure' of the argument.

2. It is an informal fallacy to say:
Socrates is mortal.
Dogs are mortal.
Therefore: Dogs are Socrates. The first two propositions are written correctly by the rules of logic, but the conclusion is written incorrectly.

Search for 'moods and figures of logic' for a full account of structure in logic.
by ceclark February 25, 2012

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Generally, a proposition is a statement, a sentence that makes a claim such as "This water tastes bad."

There are four kinds of propositions, labeled A, E, I, and O.
An 'A' proposition claims that "All A are P."
An 'E' proposition claims that "No A are P."
An 'I' proposition claims that "Some A are P."
An 'O' proposition claims that "Some A are not P."

Propositions are used in everyday language. A simple sentence can be a proposition. A proposition is labeled for the purpose of determining its validity, its truthfulness, against other statements in logical arguments when compared to other statements in that argument.

"This water tastes bad" would be an example of an 'A' proposition, because the speaker is including all of 'this' water in his claim.
A proposition: "A restaurant is not a clean place." "All cats are felines."
E proposition: "Not one smile is on any of their faces." "No cats are canines."
I proposition: "Some candy is sickeningly sweet." "Some cats are in the species called 'lion'."
O proposition: "Some days are not good days around here." "Some cats are not in the genus called 'Panthera'."
by ceclark February 25, 2012

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Belief is acceptance of a proposition, the meaning behind a declarative sentence. See example.

A belief can also be the passive acceptance of an obvious fact, such as "The car was blue" or "My father died when I was five years old". The first 'fact' is a true belief; the second sentence is a justified true belief.
I have a belief that the proposition "Red delicious apples are juicy" is true. I have a belief the proposition that "Worms grow as large as pythons" is not true.
by ceclark February 24, 2012

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A belief is the acceptance of a proposition. A true belief is one that has been examined by the believer and remains a belief. We often accept propositions, only to discover later that we were wrong. Being wrong can be the result of many things: lack of other knowledge that would have caused disbelief; a persuasive argument that you later reject; the proposition was rational-sounding but it was a fallacy.

A rational proposition that is not a fallacy has justification, that is, it is 'justified'. This means the logic is sound and it has a correspondence to facts of reality. (See 'correspondence truth').

Therefore, a 'justified true belief' is one that has been shown to be logically sound, or is accepted as logically sound.

It may or may not be 'defeasible', in other words, defeatable, by a better argument. The Copernican Revolution was the defeat of Catholic justified true belief, by the arguments of Galileo who used the mathematics of Copernicus. (See 'defeator arguments' or 'defeasors')
President Kennedy had a justified true belief that we could get to the moon, because he was shown the proof, without which his belief could not have been justified.
by ceclark January 21, 2012

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