"Why is the Earth habitable?" "Because it's in a habitable zone"
   "Why is there life on earth?" "Because life works well on
   Earth". I like these kinds of answers. I'm not being sarcastic.
   They're actually the only decent answers we have for these
   questions. [1]#Affordance [2]#Goldilocks

References

   Visible links
   1. https://plus.google.com/s/%23Affordance
   2. https://plus.google.com/s/%23Goldilocks