Sagan said:

Sagan, en un artículo de Biostranomy News de 1995, defendiendo su SETI:

Evolution is opportunistic and not foresighted. It does not "plan" to develop intelligent life a few billion years into the future. It responds to short-term contingencies. And yet, other things being equal, it is better to be smart than to be stupid, and an overall trend towards intelligence can be perceibed in the fossil record.
[...]
In the case of extraterrestrial intelligence, let us admit our ignorance, put aside a priori arguments, and use the technology we are fortunate enough to have developed to try and actually find out the answer. That is, I think, what Charles Darwin -who was converted from orthodox religion to evolutionary biology by the weight of observational evidence- would have advocated.