Deduction
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'''Deductive Logic''' is the method of non contradictory identification. It is based on the classical [[The Laws of Classical Logic|axioms]] of Aristotelean logic. ''Deductive arguments'' are akin to mathematical equations: they present a series of categories or definitions in a series of equivalencies. For this reason, the conclusion of a deductive argument necessarily follows from its premises, in the same way that ''4'' follows from the "premises" of ''2+2=''. In the opinion of this author, the most elegant form of a deductive argument is Aristotle's syllogistic logic, or [[Classical Logic|classical deductive logic]]. | '''Deductive Logic''' is the method of non contradictory identification. It is based on the classical [[The Laws of Classical Logic|axioms]] of Aristotelean logic. ''Deductive arguments'' are akin to mathematical equations: they present a series of categories or definitions in a series of equivalencies. For this reason, the conclusion of a deductive argument necessarily follows from its premises, in the same way that ''4'' follows from the "premises" of ''2+2=''. In the opinion of this author, the most elegant form of a deductive argument is Aristotle's syllogistic logic, or [[Classical Logic|classical deductive logic]]. | ||
| - | Generally, it is held by logicians that deductive arguments work from general rules to specific conclusions. For example | + | Generally, it is held by logicians that deductive arguments work from general rules to specific conclusions. This is a childish oversimplification of what deduction is. For example while the following categorical syllogism goes from the general to the specific: |
<pre> | <pre> | ||
All humans are mortal | All humans are mortal | ||
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Therefore, Socrates is mortal | Therefore, Socrates is mortal | ||
</pre> | </pre> | ||
| - | + | '''...it is not necessary that deductive arguments move from general or universal statements, to specific or particular statements''' , for example, the following disjunctive syllogism/deductive argument works from particular premises to a general conclusion: | |
<pre> | <pre> | ||
If Socrates if human, then Socrates is mortal | If Socrates if human, then Socrates is mortal | ||
Current revision as of 19:59, 18 September 2008
Deductive Logic is the method of non contradictory identification. It is based on the classical axioms of Aristotelean logic. Deductive arguments are akin to mathematical equations: they present a series of categories or definitions in a series of equivalencies. For this reason, the conclusion of a deductive argument necessarily follows from its premises, in the same way that 4 follows from the "premises" of 2+2=. In the opinion of this author, the most elegant form of a deductive argument is Aristotle's syllogistic logic, or classical deductive logic.
Generally, it is held by logicians that deductive arguments work from general rules to specific conclusions. This is a childish oversimplification of what deduction is. For example while the following categorical syllogism goes from the general to the specific:
All humans are mortal Socrates is human Therefore, Socrates is mortal
...it is not necessary that deductive arguments move from general or universal statements, to specific or particular statements , for example, the following disjunctive syllogism/deductive argument works from particular premises to a general conclusion:
If Socrates if human, then Socrates is mortal Socrates is human Therefore, Socrates is mortal
We can call a deductive logical system an a priori system. This means that we can make up such a system without any observation or experimental examination.We can create a set of categories like squares or circles or letters, and a set of self consitent rules that follow a set of definitions, all without having to ever experience such "things".
Philosophers like to say that a "brain in vat" set apart from the rest of the universe could create an a priori system.
