Philosophy - logical or illogic?
IS IT LOGIC OR ILLOGIC?
Applying Deductive Reasoning In the case of deductive reasoning – the goal is to produce a sound argument. A deductive argument in sound if the reasoning is valid (meaning the form is correct) and the premises are true.
Syllogisms
Grouped into three categories – categorical, disjunctive, hypothetical
Categorical Syllogisms whether things belong or do not
The major premise and minor premise and conclusion express things that categorize things
Proceeds from a general premise to specific conclusion
All CS include:
A middle tem that appears in the major and minor premise
A predicate term that appears in the major premise and conclusion
A subject term that appears in the minor premise and conclusion
Example: middle term predicate All humans are mortals. All A are B
Subject Socrates is a human. C is an A Therefore, Socrates is a mortal. Therefore, C is a B
The syllogism is sound and valid – because the form is correct and the premises are true.
Another example:
All cats are pigs. All A are B
Garfield is a cat. C is an A
Therefore, Garfield is a pig. Therefore, C is a B
This syllogism is valid – because it uses correct form. However, the argument is not sound because the major premise is false (and if one or more of the premises are false – the argument is not sound)
Validity – governed by the form of an argument
Soundness – governed by the form and truth of the premises
Another characteristic of categorical is that propositions can be universal or particular
(Universal = refers to all things included/not included in a category; particular = when only one/some are included/not included in a category) Example: Universal All students are people All A are B No dogs are cats No A are B Example: Particular Garfield is a cat A is a B Some gymnasts are girls Some A are B
Testing the Validity of Categorical Syllogisms
So how do you know whether a CS is valid or
Applying Deductive Reasoning In the case of deductive reasoning – the goal is to produce a sound argument. A deductive argument in sound if the reasoning is valid (meaning the form is correct) and the premises are true.
Syllogisms
Grouped into three categories – categorical, disjunctive, hypothetical
Categorical Syllogisms whether things belong or do not
The major premise and minor premise and conclusion express things that categorize things
Proceeds from a general premise to specific conclusion
All CS include:
A middle tem that appears in the major and minor premise
A predicate term that appears in the major premise and conclusion
A subject term that appears in the minor premise and conclusion
Example: middle term predicate All humans are mortals. All A are B
Subject Socrates is a human. C is an A Therefore, Socrates is a mortal. Therefore, C is a B
The syllogism is sound and valid – because the form is correct and the premises are true.
Another example:
All cats are pigs. All A are B
Garfield is a cat. C is an A
Therefore, Garfield is a pig. Therefore, C is a B
This syllogism is valid – because it uses correct form. However, the argument is not sound because the major premise is false (and if one or more of the premises are false – the argument is not sound)
Validity – governed by the form of an argument
Soundness – governed by the form and truth of the premises
Another characteristic of categorical is that propositions can be universal or particular
(Universal = refers to all things included/not included in a category; particular = when only one/some are included/not included in a category) Example: Universal All students are people All A are B No dogs are cats No A are B Example: Particular Garfield is a cat A is a B Some gymnasts are girls Some A are B
Testing the Validity of Categorical Syllogisms
So how do you know whether a CS is valid or