1. Spotting Fallacies

2. Fallacy Fallacies are those arguments which display errors in reasoning.

3. Fallacies are often persuasive but contain flaws: 1. Structure: failed link between premises and conclusion (making the argument invalid).

4. 2. Bad reasoning: often a false premise which is so because of a very general nature. (p1) If Doctor Who is on TV, it must be Saturday. (p2) It is Saturday (c) Doctor who is on TV

5. (p1) If Doctor Who is on TV, it must be Saturday. (p2) It is Saturday (c) Doctor who is on TV (p1) If (antecedent) then (consequent) (p2) (consequent) (c) (antecedent)  This structure of this argument relies upon us affirming the consequent to confirm the antecedent.  However as the consequent is too vague we cannot do this.  This is called the fallacy of affirming the consequent.

6. Similarly… (p1) If Doctor Who is on TV it must be Saturday. (p2) It is not the case that Doctor Who is on TV (c) It is not the case that it is Saturday. (p1) If (antecedent) then (consequent) (p2) It is not the case that (antecedent) (c) It is not the case that (consequent)  This is the fallacy of denying the antecedent.  The denial of the antecedent does not fully convince us of reasons to deny the consequent.

7. Important fallacies Begging the question/circularity Slippery slope Post hoc ergo propter hoc False dilemma Attacking the person Appeals to consequences Appeals to authority Appeals to illegitimate authority Arguments from ignorance (appeals to ignorance).

8. The Slippery Slope Fallacy Arguing that one thing will lead to another without further argument. Famously used by in politics – often concerning drug use, homosexuality etc

9. The Slippery Slope Fallacy (p) Almost all heroin addicts were milk drinkers before becoming heroin addicts. (c) Milk drinkers tend to become heroin addicts.

10. The Slippery Slope Fallacy Typically, these arguments take one step in a certain direction and then make great leaps in this direction. Give an inch and take a mile thinking. P.57 example. This is often found in political rhetoric: Theresa May: The case of an illegal immigrant who could not be deported "because he had a pet cat" showed why the Human Rights Act "needs to go".

11. Tasks on p.58

12. Post hoc ergo propter hoc  Latin: after this, therefore because of this’  False general principle – because event 2 follows event 1, event 1 caused event 2. ‘Most hard drug users start off as ‘soft’ drug users. This demonstrates that ‘soft’ drug use causes ‘hard’ drug use.’  Hidden premise here: ‘When one thing precedes another, then the former is the cause of the latter’  This hidden premise belongs in all post hoc ergo propter hoc arguments.  It is not invalid in structure but it is certainly unsound.  We could say: ‘Most hard drug users start off as breast milk users. (HIDDEN PREMISE HERE) Banning breast milk will prevent hard drug use.’ ‘Most of my silly actions take place after drinking. (HIDDEN PREMISE HERE). Not drinking would forever stop me from performing silly actions. ‘

13. Tasks p.61

14. Begging the question Bad pattern of reasoning. Fails to provide grounds for accepting conclusion. (p1) The Bible says that God exists. (p2) The Bile is the true Word of God (c) God exists  The reasoning her presupposes God exists, therefore it simply continues to beg the question.

15. Begging the question David: Look, women shouldn’t become soldiers. Anna: Why? David: Because it's a job for men only. Again, the conclusion is already presupposed by the premises.

16. Circularity This involves a chain of reasoning which is circular… We can see circularity from an analysis of two arguments and how they rely upon each other to be true and thus can never be proven as each argument refers back to the other in a circular fashion.