“You make a valid point.” Have you ever heard anyone say this? When people say this they probably mean something like “you make a good point,” but when you enter the world of philosophy, you realise that the word “valid” is reserved for a different purpose. Similarly, in everyday speech when someone says “He has convinced me, because he made a valid argument,” they probably mean that someone has made a convincing argument. But in logic, the fact that an argument is valid certainly doesn’t indicate that it’s persuasive – or even good.