I believe the topic of convergence is important for two main reasons. One is widely acknowledged, if as often subject to procrustean procedures of accommodation. It concerns phylogeny, with the obvious circularity of two questions: do we trust our phylogeny and thereby define convergence (which everyone does), or do we trust our characters to be convergent (for whatever reason) and define our phylogeny? As phylogeny depends on characters, the two questions are inseparable. … Even so, no phylogeny is free of its convergences, and it is often the case that a biologist believes a phylogeny because in his or her view certain convergences would be too incredible to be true. … During my time in the libraries I have been particularly struck by the adjectives that accompany descriptions of evolutionary convergence. Words like, ‘remarkable’, ‘striking’, ‘extraordinary’, or even ‘astonishing’ and ‘uncanny’ are common place…the frequency of adjectival surprise associated with descriptions of convergence suggests there is almost a feeling of unease in these similarities. Indeed, I strongly suspect that some of these biologists sense the ghost of teleology looking over their shoulders.
(Simon Conway Morris,
Life’s Solution: Inevitable Humans in a Lonely Universe, pp. 127-128 (Cambridge University Press, 2003).)