WOK: Reason

here are three things you should know about to get started in understanding reason: 

Deductive reasoning is the ability to use logical deduction This allows us to go from starting ideas (premises) to reach valid conclusions. Here’s a simple example: Premises 1: Rex is a dog. Premises 2: All dogs have fur (remember this doesn’t have to be true) Question: Does Rex have fur? Valid Conclusion: Yes Rex has fur. Going from premises to conclusions like this is called logical ‘deduction’. deduction leads to valid conclusions. This does not mean that the conclusions are true. What it means is that if the premises are true then the conclusions will be true. Here’s another example. Premises 1: Peter is a man Premises 2: All men have eight legs Question: Does Peter have eight legs? Valid conclusion: Yes, Peter has eight legs. Remember that this might not be true, people don’t usually have more than two legs! However, the conclusion is still logically valid because it follows from the two starting premises. 

Second is the ability to use logical Induction When we used deductive logic above we made general statements (about men and about dogs). We used these to show something specific about a man (Peter, showing he had eight legs) and a dog (Rex, showing he had fur). With inductive logic we take a specific example to tell us something about the general. For example, you might have noticed that most windows are made of glass. We could say the following Step one: All the windows I have seen are made of glass Step two: Therefore all windows are made of glass Notice that inductive reasoning can involve probability. You might think that because you’ve seen so many windows and they were all made of glass, that all windows are made of glass. However, there is nothing stopping a window from being made of plastic or of jelly. You should know something about logical induction: it is what we call ‘inferential’. This is that it makes a statement which is not strictly provable. There’s no way I can prove that all the windows in the world are made of glass. The idea that they are is just inferred from my experience. 

INDUCTIVE STRENGTH

An inductively strong argument is one in which the evidence, once accepted, establishes a firm probability that the conclusion is true.

When judging inductive strength an argument can be considered to be strong if the level of probability established for the conclusion is high.

Three tests for soundness

1. Sufficient number of observations

2. Varying circumstances

3. Exceptions (easier to disprove than prove)