|Pierre Teilhard de Chardin|
In their popular science book, The Anthropic Cosmological Principle, published in 1986, cosmologists John Barrow and Frank Tipler define three different anthropic principles:
1. The weak anthropic principle or WAP (this was offered by Brandon Carter in 1973): the simple verification that the fact that we are here imposes certain restrictions on the universe, such as having lasted long enough for intelligent life to appear.
2. The strong anthropic principle or SAP: the claim that making possible the emergence of intelligent life was a necessary requirement for the universe.
3. The final anthropic principle or FAP: The claim that, once intelligent life has appeared in the universe, it cannot disappear.