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2.4 DEDUCTIVE REASONING. Playing the game of logic well. Law of Detachment [(p>>q)^p]>>q. If p, then q is True And p is True Then q is True An example: If a vehicle is a car, then it has four wheels. A Cadillac is a car.
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2.4 DEDUCTIVE REASONING Playing the game of logic well
Law of Detachment[(p>>q)^p]>>q • If p, then q is True • And p is True • Then q is True • An example: If a vehicle is a car, then it has four wheels. • A Cadillac is a car. • Then (by the law of detachment) it (the caddy) has four wheels.
Law of Syllogism[(p>>q)^(q>>r)] >>(p>>r) • If p, then q is True • And If q, then r is True • Then If p, then r is True • An example: If Gertrude takes the Cadillac for a spin, she will stop at the post office. • If she stops at the post office, then she will buy stamps. • Thus (by the law of syllogism) If Gertrude takes the Cadillac for a spin, then she will buy stamps.
Cornerstone of Geometry • These are two of the laws of logic that provide a system for reaching logical and always true conclusions. • This system is called Deductive Reasoning