Good And Bad Reasons For Believing

posted May 14, 2011, 9:08 PM by Viva Paco   [ updated May 14, 2011, 9:25 PM ]
By Richard Dawkins

Dear Juliet,

Now that you are ten, I want to write to you about something that is important to me. Have you ever wondered how we know the things that we know? How do we know, for instance, that the stars, which look like tiny pinpricks in the sky, are really huge balls of fire like the sun and are very far away? And how do we know that Earth is a smaller ball whirling round one of those stars, the sun? The answer to these questions is "evidence." Sometimes evidence means actually seeing (or hearing, feeling, smelling.....) that something is true. Astronauts have traveled far enough from earth to see with their own eyes that it is round. Sometimes our eyes need help. The "evening star" looks like a bright twinkle in the sky, but with a telescope, you can see that it is a beautiful ball - the planet we call Venus. Something that you learn by direct seeing (or hearing or feeling.....) is called an observation.
Often, evidence isn't just an observation on its own, but observation always lies at the back of it. If there's been a murder, often nobody (except the murderer and the victim!) actually observed it. But detectives can gather together lots or other observations which may all point toward a particular suspect. If a person's fingerprints match those found on a dagger, this is evidence that he touched it. It doesn't prove that he did the murder, but it can help when it's joined up with lots of other evidence. Sometimes a detective can think about a whole lot of observations and suddenly realize that they fall into place and make sense if so- and-so did the murder.