Beatty’s thesis, captured in his most often-cited passage, is this:
“ [A] ll distinctively biological generalizations describe evolutionarily contingent states of nature…This means that there are no laws of biology. For, whatever ‘laws’ are, they are supposed to be more than just contingently true” (Beatty 1995, p. 46).
Hamilton (2005) has detected a patent difficulty in comparing degrees of stability when drawing a continuum, “since it is not clear how to compare the degree of stability of regularities in any fine-grained or principled way” (Hamilton 2005, p. 69).
L iterature on constraints takes evolutionary contingency into account in a non-trivial sense according to which the origin of constraints is itself evolutionarily contingent and accounts for their taxon specificity
“ biases on the production of variant phenotypes or limitations on phenotypic variability caused by the structure, character, composition, or dynamics of the developmental system” which “undoubtedly play a significant role in evolution” (Maynard-Smith et. al. 1985, p. 265)
C onsists in “identifying constraint with a particular evolutionary outcome or pattern,” thus concluding that “the responsible mechanism is, by definition, ‘constraint’” (Schwenk and Wagner 2003, p. 53)
McKitrick’s (1993) notion of phylogenetic constraints endorses/emends this view
Schwenk and Wagner´s (2003) analysis of the conflation strategy
S ympathetic toward s it , provided that the circumstances in which selection acts as a constraint are specified contextually
By establishing a set of fixed points (specifying factors) around which constraint can be organized, they propose a strategy to draw the boundaries of operation of constraint and outline its explanatory power