http://www.ck12.org Chapter 2. Reasoning and Proof
2.5 Deductive Reasoning
Here you’ll learn how to deductively draw conclusions from facts using the Law of Detachment, the Law of
Contrapositive, and the Law of Syllogism.
What if, in a fictitious far-away land, a poor peasant were awaiting his fate from the king? He is standing in a
stadium, filled with spectators pointing and wondering what is going to happen. Finally, the king directs everyone’s
attention to two doors, at the floor level with the peasant. Both doors have signs on them, which are below:
TABLE2.4:
DoorA DoorB
IN THIS ROOM THERE IS A LADY, AND IN THE
OTHER ROOM THERE IS A TIGER.IN ONE OF THESE ROOMS THERE IS A LADY,
AND IN ONE OF THE OTHER ROOMS THERE IS
A TIGER.
The king states, “Only one of these statements is true. If you pick correctly, you will find the lady. If not, the tiger
will be waiting for you.” Which door should the peasant pick? After completing this Concept, you’ll be able to use
deductive reasoning to solve this problem.
Watch This
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/52480CK-12 Foundation: Chapter2DeductiveReasoningA
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/1379James Sousa: Introduction to Deductive Reasoning
Guidance
Logicis the study of reasoning. Deductive reasoningdraws conclusions from facts. Typically, conclusions are
drawn from general statements about something more specific.