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Reason. Reason It rained last night. It rained last night. There are no sharks in Sun-Moon lake. There are no sharks in Sun-Moon lake. The sun will rise.

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Presentation on theme: "Reason. Reason It rained last night. It rained last night. There are no sharks in Sun-Moon lake. There are no sharks in Sun-Moon lake. The sun will rise."— Presentation transcript:

1 Reason

2 Reason It rained last night. It rained last night. There are no sharks in Sun-Moon lake. There are no sharks in Sun-Moon lake. The sun will rise tomorrow. The sun will rise tomorrow. Batman is mortal. Batman is mortal. The next Britney Spears album will suck. The next Britney Spears album will suck. How do you know the following?

3 Reason Surprise, surprise, Reason is also known as Logic.

4 Reason The school of Philosophy that adheres to this principle is called Rationalism…

5 Reason In Logic an assumption is called a PREMISE In Logic an assumption is called a PREMISE If you have a premise a CONCLUSION has to follow… If you have a premise a CONCLUSION has to follow…

6 Reason Dogs are mammals Dogs are mammals Fido is a dog. Fido is a dog. Therefore Fido is a mammal. Therefore Fido is a mammal. Monkeys are mammals Monkeys are mammals You are a mammal. You are a mammal. Therefore you are a monkey…? Therefore you are a monkey…?

7 Reason These kind of deductive arguments are called syllogisms. Syllogisms contain the following : Two premises and a conclusion Two premises and a conclusion Three terms, each of which occurs twice (dogs, mammals, Fido) Three terms, each of which occurs twice (dogs, mammals, Fido) Quantifiers, such as “all”, “some” or “no”, these tell us which quantity is referred to. Quantifiers, such as “all”, “some” or “no”, these tell us which quantity is referred to.

8 Reason But what about our monkey example? In syllogisms we also need to distinguish between TRUTH and VALIDITY. In syllogisms we also need to distinguish between TRUTH and VALIDITY. Truth : Is concerned with what is actually the case. Truth : Is concerned with what is actually the case. Validity : Is concerned whether or not the conclusion follows the premises. Validity : Is concerned whether or not the conclusion follows the premises. A syllogism can be true, but not valid (i.e. make logical sense). It can also be valid but not true. A syllogism can be true, but not valid (i.e. make logical sense). It can also be valid but not true.

9 1. All zebras are striped animals. No zebras are polar bears. Therefore, no polar bears are striped animals. 2. All clowns are funny individuals. Some sad people are clowns. Therefore, some sad people are funny individuals. 3. Some sticky substances are yucky things. All taffy is a sticky substance. Therefore, some taffy is a yucky thing. 4. All items made of gold are expensive items. Some rings are items made of gold. Therefore, some rings are expensive items. 5. All flies are winged creatures. All butterflies are winged creatures. Therefore, all butterflies are flies.

10 Reason Your Task : Research rationalism… Research rationalism… Write your own definition for this concept… Write your own definition for this concept… Text book pg. 115 (make up your own valid syllogisms) Text book pg. 115 (make up your own valid syllogisms) What do you think?  Are you rational? Is logic/reason important to you?

11 Reason Follow this link : http://www.plastelina.net/games/game1.html


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