 Thus, philosophers have done a lot of work on challenging conceptual questions about the various senses of ‘contingency’ and their relationship to other macroevolutionary ideas. One problem lurking in the background of this discussion is empirical: how can scientists even tell whether evolutionary history is contingent or (say) convergent? Conway Morris (2003) assembles a whole catalog of examples of evolutionary convergence in an effort to provide counterevidence against Gould’s contingency thesis. One important issue here is to find a principled way of distinguishing cases of convergent evolution (where unrelated lineages subject to similar selection pressures evolve similar traits) from parallel evolution (where lineages with similar traits to start with follow similar evolutionary trajectories) (Pearce 2012). Another issue is that one can multiply convergences by giving coarser-grained descriptions of the traits in question—for example, by counting agriculture in humans and some ant species as the same trait (Sterelny 2005). Powell &amp; Mariscal (2015) argue that not all of the putative examples of convergence really tell against the contingency thesis, and they try to specify more clearly what would actually count as evidence against contingency.