What is an ‘Assumption ’? Things that make an ass out of u and me

1. What is an ‘Assumption’? Things that make an ass out of u and me • Objectives • To understand what is meant by the term assumption’ • To be able to identify the assumptions in arguments • To understand how assumptions affect the of an argument I assume when I sit on this chair, it will not collapse!(a dangerous assumption to make?)

2. Assumptions: A Starter ‘Joe better watch out there is a polar bear behind him’ List as many assumptions as you can E.g., the bear is alive!

3. Assumptions & finding them Assumption = An unstated reason in an argument Or what the author must be believe to be true but has not stated The Negative Test One way to check for an assumption is the negative test What is the assumption in the following argument ‘Giant pandas are an endangered species. They should be protected’ The assumption is that they are worth protecting If we change this to a negative statement they are not worth protecting the argument breaks down and so we have proved its an assumption or something the author must believe to be true but has not stated

4. Assumptions: An example Marco Polo is best known as the first person from the West to have visited China. But in his writings about his visit there, he nowhere mentions the Great Wall, tea or porcelain. Therefore he can’t have ever visited China. His book about his travels to that country must have been written using information he’d picked up from those people who had been there. What is the underlying assumption here? That you have to talk about the Great Wall, tea or porcelain if you have been to China (so nothing else there then!) Now look at the examples on the Assumptions sheet.

5. There is no point in going into the chemist’s shop to consult the pharmacist at the moment. There is only a woman behind the counter • An assumption is something that is not said yet is considered obvious to the arguer. • An assumption can sound or unsound. • The trick is being able to spot the assumption and deciding if it is integral to the argument.

6. In analysing arguments, it is just as essential to identify and evaluate assumptions as it is to examine the explicit reasons. This is because the assumptions are playing an important role in the reasoning process, and the conclusion can only be accepted if both the reasons and the assumptions are convincing.

7. Your turn – spot 2 assumptions It is important to reduce the amount of air travel as it has a significant impact on global warming. Increasing the cost of cheap holiday flights will substantially reduce air traffic. An assumption in this argument is that increasing the cost of holiday flights will discourage passengers from taking them. This may not be the case as people may be so keen to fly to holiday destinations that they are prepared to pay more. Another assumption is that holiday traffic is a substantial element in air travel, whereas it may be far outweighed by business and military uses of aircraft.

8. Caution!!! • Assumptions are missing parts of the argument NOT explicit statements within it. • In the previous example some might try to claim that the opening statement about the impact of air travel is an assumption because it is not backed up. However it is not an assumption – in that instance you can only say the writer is making a causal link between air travel and global warming that is not justified by the article.

9. What is the assumption? • Twenty per cent of the people in the world own 80% of its wealth. Clearly, action needs to be taken to redress the balance • Is the assumption a flaw in this argument?

10. There is an assumption here that gross global inequalities are unacceptable. However, it is a view that the majority would accept, so it would be difficult to make a case for this being a flawed argument because of its assumption. Try to remember to precede the word ‘assumption’ with an adjective such as ‘false’ or ‘sound’.

11. A tip! • To help you identify crucial assumptions, use the negative or reverse test. Convert what you think is an assumption to its opposite and see whether the conclusion still holds. • Twenty per cent of the people in the world own 80% of its wealth. (R) • Gross global inequalities are acceptable. (reversed assumption) • Clearly, action needs to be taken to redress the balance. (C) • Using the reverse test should increase your confidence when identifying assumptions.

12. Assumptions: A Plenary Reflect back over the day – We make millions of assumptions every day List three assumptions you have made today and share them with your partner