In Orthodoxy, Chesterton tackles Nietzsche claim that 'god is dead', death by evolution. He argues that if the theory of evolution is used as an argument for the end of faith or religion than this isn't simply a problem for religion alone; it is a problem for all thought and rationalism.
For Chesterton the existence or fact of evolution is a non-issue: it only describes how man has ascended from apes. However, if that ascent can be said to "destroy religion", that is kill God, than it also kills 'the self'. His argument follows that if evolution is true, and that we have diverged from apes and diverged from fish and so on as we ascended from the trunk of the family tree, then it is false to think of ourselves as humans, and they 'as apes' and them 'as fish' and so on. We are all one and the same 'thing', not 'things' as Chesterton says. Such that we are same and this accounts for every-thing, we can not therefore discuss some-thing in terms of itself. We are it and importantly then cannot separate ourselves from our subject and think about it objectively and rationally.
Chesterton's point that there is no 'man', and no 'ape' is well made: these titles and the concept of species are only a practical categorization, and abstract away from the impact of time on the different variations that have come and gone However, Descartes's famous quip is not so easily inversed as Chesterton argues. Like the continuance of religion, our ability to think about things is not diminished by the knowledge that we are all variations of the same thing. Through birth and death we are individual expressions and variations of a previous ancestor and our thoughts and rationalism's are not representative of all previous members, but only ourselves. In this sense we, as the conceptualized group of 'humans' are an infinite number of 'things', capable of cognition and independently can be rational, irrational, believe in a god or gods, or personally denounce the former as a fallacy. Importantly these are personal statements, not representative of the family, and up to each individual to decide individually. It is the independent cognition; separate from the family and unique each member that refutes Chesterton's statement and thus his argument.
Notably, despite Nietzsche's statement and similar arguments by Dawkins, we have seen major religion continue to proliferate across the world especially in the US and it could hardly be said that the acceptance of evolution as a scientific fact has led to the destruction of religion. Quite the contrary, there has been a trend of rejecting evolutionary theory in the majority of the US population alongside this growth in religiousness. As the theory of evolution can be epitomized as the culmination of a specific individuals lifetime of rational thought, Chesterton's argument could be reinvented: perhaps it is the proliferation of religion that hearkens the destruction of rationalism?