What Does It All Mean? A Very Short Introduction to Philosophy2

The most radical conclusion to draw from this would be that your mind is the only thing that exists. This view is called solipsism.

The main concern of philosophy is to question and understand very common ideas that all of us use every day without thinking about them. A historian may ask what happened at some time in the past, but a philosopher will ask, "What is time?" A mathematician may investigate the relations among numbers, but a philosopher will ask, "What is a number?"

In fact most of the time you don't even think about the mental states that make you aware of those things: you seem to be aware of them directly. But how do you know they really exist?