UGED1111B LOGIC: DEDUCTION & INDUCTION (I) 2019-20, Summer Sapphires, WONG Sin Ting Tree Hole for UGED1111B 2 Agenda 3 Types of Argument ◼ Deductive Arguments and Inductive Arguments Possibilities Types of Proposition Types of Argument 4 Deductive Arguments (演繹論證) ◼ ◼ A deductive argument incorporates the claim that its conclusion is impossible to be false if all its premises are true. The conclusion of a deductive argument can be conclusively supported by its premises. Deductive Arguments 5 Example 1 Example 2 1. All Disney animated movies are great. 2. Coco is a Disney animated movie. 1. 從來是指三次。 2. 你三次不接女朋友電話。 3. Coco is great. 3. 你從來不接女朋友電話。 Types of Argument 6 Inductive Arguments (歸納論證) ◼ ◼ An inductive argument incorporates the claim that its conclusion is improbable to be false if all its premises are true. The conclusion of an inductive argument can be strongly supported by its premises. Inductive Arguments 7 Example 1 Example 2 1. The sun rose from the east today. 2. The sun rose from the east yesterday. ︙ 1.上次也是我錯。 2.今次也是我錯。 3. The sun will rise from the east tomorrow. 3. 永遠都是我錯！ Types of Argument 8 In short, a deductive argument can guarantee the truth of its conclusion by the truth of its premises, while an inductive argument cannot. Conclusion Conclusion Content of premises Deductive Argument Content of premises Inductive Argument Types of Argument 9 Peter Pan Inside Out Sleeping Beauty The Lion King Coco Frozen Aladdin Mulan Lady and the Tramp Dumbo Zootopia The Aristocats Cinderella Tangled Monsters, Inc. Ratatouille The Little Mermaid Bambi Beauty and the Beast Deductive Argument 1. All Disney animated movies are great. 2. Coco is a Disney animated movie. 3. Coco is great. Types of Argument 10 Today 1. The sun rose from the east today. 2. The sun rose from the east yesterday. ︙ 3. The sun will rise from the east tomorrow. Tomorrow Yesterday 1 day before yesterday 3 day before yesterday 4 day before yesterday 2 day before yesterday 5 day before yesterday 6 day before yesterday n day before yesterday Inductive Argument Possibilities 11 Technological Possibility ◼ Physical Possibility ◼ Do not exceed our current technological constraints. Do not exceed our physical constraints. Logical Possibility ◼ Do not exceed our logical constraints. Possibilities 12 Technological Possibility ◼ Do not exceed our current technological constraints. ? Possibilities 13 Physical Possibility ◼ Do not exceed our physical constraints. Possibilities 14 Logical Possibility ◼ Do not exceed our logical constraints. Basically, everything that currently exists in our world is logically possible. What is logically impossible? Circle-square?? Possibilities 15 What is a circle-square? Circle Circle-square?? Square A circle-square is logically impossible, as it violates the law of non-contradiction. Possibilities 16 Summary Circle-square Move faster than light. Logical Possibility Physical Possibility Technological Possibility Westworld’s robots 32GB USB flash drive Types of Proposition 17 Tautological proposition ◼ Self-contradictory proposition ◼ A proposition that is necessarily true. A proposition that is necessarily false. Contingent proposition ◼ A proposition that is neither necessarily true nor necessarily false. Types of Proposition 18 Tautological proposition ◼ A proposition that is necessarily true. Not possible to be false EXAMPLE 這球十二碼，要麼進，要麼不進。 All bachelors are unmarried. 如果梁振英是前任行政長官，則上一任行政長官是梁振英。 It is false that some circles are not round. It’s necessarily false! Types of Proposition 19 Self-contradictory proposition ◼ A proposition that is necessarily false. Not possible to be true EXAMPLE 這球十二碼既進亦不進。 Some circles are not round. 梁振英是前任行政長官，但上一任行政長官並不是他。 It is false that all bachelors are unmarried. It’s necessarily true! Types of Proposition 20 Contingent proposition ◼ A proposition that is neither necessarily true nor necessarily false. EXAMPLE France is the FIFA World Cup 2018 Champion. contingently true 《降魔的2.0》是無綫電視目前的八點半檔連續劇。 It is compulsory for Hong Kong students to wear the veil to school. contingently false 現任香港特別行政區行政長官是曾俊華。 Exercise (3) 21 Determine the types of the following propositions: References 22 ➢ ➢ ➢ Copi, I., Cohen, C., & McMahon, K. (2011). Introduction to Logic (14th ed. / Irving M. Copi, Carl Cohen, Kenneth McMahon ed.). Upper Saddle River, NJ: Pearson Education. Hurley, P. (2015). A Concise Introduction to Logic (12th ed.). Australia ; Stamford, Ct.: Cengage Learning. Lau, J. (2011). An Introduction to Critical Thinking and Creativity : Think More, Think Better. Hoboken, N.J.: Wiley.