Difference between revisions of "Premise"
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A '''premise''' in debate or logic means the proposition from which a conclusion is drawn. The proposition (the '''premise''') can be either proved or supposed. It is needed in order to apply logic and draw the desired conclusion. | A '''premise''' in debate or logic means the proposition from which a conclusion is drawn. The proposition (the '''premise''') can be either proved or supposed. It is needed in order to apply logic and draw the desired conclusion. | ||
| − | A common flaw in reasoning is to apply correct logic to a faulty '''premise''', as in " | + | A common flaw in reasoning is to apply correct logic to a faulty '''premise''', as in "If embryonic [[stem cell]] research will save lives, then we should support it!" The '''premise''' of embryonic [[stem cell]] research saving lives is unproven and unjustified as a supposition, as all research has shown it to be essentially worthless. The laws of formal logic show that one can arbitrarily draw conclusions from such worthless premises, since a logical structure of the kind "If A, then B" only establishes a truth function between a true A and its consequent B; however, all statements derived from a false A are equally true in a logical sense. In order to tie the truth value of a conclusion exclusively to that of its antecedent, statements of the sort "Only if A, then B" have to be used. This is also very useful for logically identifying prudent behaviour in cases of dichotomous choice. Consider the following statement: "We should only support stem cell research if it will save lives". After the falsity of the antecedent "stem cell research will save lives" has been established, one can logically derive the conclusion that this policy should not be supported. |
The term the '''premises''' also has a legal and popular meaning, to include both land and buildings together as property, as in "he was on the '''premises''' at the time." | The term the '''premises''' also has a legal and popular meaning, to include both land and buildings together as property, as in "he was on the '''premises''' at the time." | ||
Revision as of 14:33, January 16, 2010
A premise in debate or logic means the proposition from which a conclusion is drawn. The proposition (the premise) can be either proved or supposed. It is needed in order to apply logic and draw the desired conclusion.
A common flaw in reasoning is to apply correct logic to a faulty premise, as in "If embryonic stem cell research will save lives, then we should support it!" The premise of embryonic stem cell research saving lives is unproven and unjustified as a supposition, as all research has shown it to be essentially worthless. The laws of formal logic show that one can arbitrarily draw conclusions from such worthless premises, since a logical structure of the kind "If A, then B" only establishes a truth function between a true A and its consequent B; however, all statements derived from a false A are equally true in a logical sense. In order to tie the truth value of a conclusion exclusively to that of its antecedent, statements of the sort "Only if A, then B" have to be used. This is also very useful for logically identifying prudent behaviour in cases of dichotomous choice. Consider the following statement: "We should only support stem cell research if it will save lives". After the falsity of the antecedent "stem cell research will save lives" has been established, one can logically derive the conclusion that this policy should not be supported.
The term the premises also has a legal and popular meaning, to include both land and buildings together as property, as in "he was on the premises at the time."
