“It just follows! If you believe that Mickey is a big mouse and Dumbo is a small elephant, you just have to believe that Mickey is a mouse and Dumbo is an elephant” Sure. “And that Mickey is bigger than Dumbo” No! That doesn’t follow.
This is obviously a Mickey Mouse example, but the issue it points to is important in many areas of daily life where evidence and clear arguments matter, such as politics, the law, public health and the application of technology.
We talk like this when we think that what someone has said means that they just have to agree to some conclusion (or give up one of the claims they started from). This course is about what follows from what: when it really is the case that when something is true, other things have to be true too.
We’ll look at arguments which have this special property — that if the claims they start from are true, their conclusions have to be true too — and the role that some small but important words — ‘and’, ‘or’, ‘not’, and ‘if … then …’ play in making good or bad arguments.
You will see how we can use a special made-up language — a formal language — to assess the arguments and look closely at how our everyday language and thinking work.