The anthropic Earth

This chapter focuses on the notion that we need to take account of our own existence in thinking about certain problems. This notion lies behind a set of ideas that go under the name of the anthropic principle. There are several versions of the anthropic principle to be found in the literature: for example, an authoritative book on the subject by John Barrow and Frank Tipler defines ‘weak’, ‘strong’ and ‘final’ versions of the Cosmological Anthropic Principle. The chapter invokes the exclusively ‘weak’ anthropic arguments. The weak anthropic principle states simply that the universe, as we see it, must be compatible with our own existence.