The Philosophers Toolkit Arguing Part1 - Logic

1. The Philosophers Toolkit Arguing Part1 - Logic Open mind ? Reasoning Questioning Clear thinking

2. Value of an Arguing ‘toolkit’ • Use arguments more effectively • Express yourself more clearly and precisely • Improve flexibility & creativity of thinking • Find relevance in an argument • Examine issues that you may not be an expert in more effectively • Identify flawed arguments, biases and fallacies I used logic to decide that logic does not work.

3. Some things good arguers do • Question (see The Philosophers Toolkit ppt on Questioning) • Agree or disagree by: • Providing examples & counter examples • Giving reasons (‘…because…’) • Finding distinctions • Use logic to support reasoning • Deductive • Inductive • Spot flaws in reasoning i.e. identify fallacies

4. Recognising an Argument • An argument has 2 main parts; two or more premise/s and a conclusion • Premises are statements that support the argument. • Conclusions are statements that put forward a particular argument. • Premise(s) and conclusion can come in any order • An argument exists when the premises support the conclusion, but, the premises don’t have to be true • A sound or valid argument is one where the premises have to be true and lead to a true conclusion • We use reason and logic to put forward an argument.

5. Reasoning - Deductive • A simple argument: • Premise 1 – John is a human • Premise 2 – All humans have bones • Conclusion – John has bones • Logic is used to lead from premises to conclusion • This argument is valid and sound

6. Reasoning - Inductive • A simple argument: • Premise: 100 apples examined contained pips • Conclusion: All apples contain pips • Draws a conclusion from a series of premises (ie 100 premises in the above case as we had to examine 100 apples) • Conclusion not based on logic but supports premise • Scientists use inductive reasoning to construct theories that are thought to be true in all times and places • This argument is valid and sound

7. Bad arguments: • Jim and Bill are not both drunk; Jim isn’t, so Bill is. • Ann can’t ride a bicycle because she is in the bath; and you can’t ride a bicycle in the bath. • Most con-men are smooth talking; so that a smooth talker is probably a con-man • Every number is a number or its successor; or its successor is even; so every number is even • Grass is green; so snow is white

8. Valid arguments • Everything indescribable is describable as indescribable; so everything is describable • Since there are a finite number of humans; some human had no human mother • London must be south of Messina; because London is south of Rome and Rome is south of Messina • It’s heavier than air; so it won’t fly without power.