Why do we believe what we know?

Everything we believe is connected to other things we believe in complicated ways. Sometimes we deceive ourselves, out of necessity, to hold on to an important belief. There is a way that we can explore these relationships and learn how we come to believe things, and how others do too: but first we must understand four different ways of knowing things.

Four types of knowledge

The most widely accepted definition of knowledge is justified true belief — that is, earnestly believing that something is true when it is in fact true. In this, we are talking about what is called propositional knowledge, or facts, rather than knowing how to do something. This kind of knowledge is sometimes divided into a priori knowledge, which requires reason but not experience, and a posteriori knowledge, which requires both experience and reason.

But there is another way to categorize knowledge: high and low confidence versus high and low evidence. This leads us to four quadrants that will be familiar to you:

• I: Faith
• II: Observation
• III: Philosophy
• IV: Science

Faith

We all use our faith every day, even those of us who are not religious. When you trust your partner not to have an affair…