PHL 214 Lecture Notes - Lecture 7: Logical Reasoning

• School: Ryerson University
• Department: Philosophy
• Course: PHL 214
• Professor: Thomas Land

Document Summary

To find implicit premises: search for a credible premise that would make the argument deductively valid. Use principle of charity (give people the benefit of the doubt: search for a credible premise that would make argument inductively strong. If can"t find one, then reject the argument: if steps 1 or 2 worked, evaluate soundness or cogency. Apply principle of charity: decide if argument is deductively valid, sound. If no: decide if argument is inductively strong, cogent. If no: now you know it"s a bad argument. Example: (1)the researchers shouldn"t get the prize. (2)if their vaccine prevents the spread of x virus, they should get the prize. (3)but their vaccine doesn"t work. Diagramming arguments: mark all indicator words, number all assertions in argument in order of appearance. 4: decide if these are independent or dependent premises. Identify main premises that directly support conclusion: dependent premises: depend on each other to support conclusion, cannot by itself support conclusion.