PSY 102 Lecture Notes - Lecture 5: Deductive Reasoning, Critical Thinking, Microsoft Powerpoint

• School: Ryerson University
• Department: Psychology
• Course: PSY 102
• Professor: Klaas Kraay

Document Summary

Week 5 powerpoint notes & textbook questions & lecture notes. A deductive argument intends to provide logically conclusive support for the conclusion. An argument is deductively valid if and only if it is not possible for all the premises to be true and the conclusion false. (if all the premises were true, the conclusion would have to be true too. Example of a valid argument: all bachelors are unmarried. Ivan is a bachelor: therefore, ivan is unmarried. (from 1 and 2) Note: the word valid can only be applied to arguments, not to conclusions or premises. Example of an invalid argument: some politicians are crooks, professor cray is a politician, therefore, professor cray is a crook. (from 1 and 2) Even though the premises were true it does not logically guarantee the conclusion. Using the example shown above premise 1 states that only some politicians are crooks, therefore there is a chance cray is not a crook.