A Closer Look at Inductive vs. Deductive Reasoning

1. A Closer Look at Inductive vs. Deductive Reasoning

2. Deductive vs. Inductive Reasoning • The difference: inductive reasoning uses patterns to arrive at a conclusion (conjecture) deductive reasoning uses facts, rules, definitions or properties to arrive at a conclusion.

3. Inductive reasoning - Think of it like a We start with specifics and move to generalities • Deductive reasoning – think of it like a We start with generalities and move to specifics.

4. Examples of Inductive Reasoning Some examples • Every quiz has been easy. Therefore, the test will be easy. • The teacher used PowerPoint in the last few classes. Therefore, the teacher will use PowerPoint tomorrow. • Every fall there have been hurricanes in the tropics. Therefore, there will be hurricanes in the tropics this coming fall.

5. The catalog states that all entering freshmen must take a mathematics placement test. Deductive Reasoning An Example: You are an entering freshman. Conclusion: You will have to take a mathematics placement test.

6. x 60◦ Inductive or Deductive Reasoning? Geometry example… What is the measure of angle x? Triangle sum property - the sum of the angles of any triangle is always 180 degrees. Therefore, angle x = 30°

7. Inductive or Deductive Reasoning? Geometry example… What is the next shape in the sequence?

8. 90% of humans are right handed. Joe is human, therefore Joe is right handed. DEDUCTIVE

9. You are a good student. You get all A’s Therefore your friends must get all A’s too INDUCTIVE

10. All oranges are fruits. All fruits grow on treesTherefore, all oranges grow on trees DEDUCTIVE

11. Mikhail hails from Russia and Russians are tall, therefore Mikhail is tall INDUCTIVE