  The two premises can, however, be challenged. Start with Completeness. Baker (1993), not herself a Cartesian dualist, argues that if the principle threatens to undermine our ordinary (and scientific) explanatory practices—many of which cite the mental—it’s Completeness that has to go. Entrenched explanatory practices trump any abstract metaphysical principles with which they might conflict (see also §§6.3, 7.5). Others argue that physical science, far from supporting the principle, may in fact undermine it. Hendry (2006) finds indications of “downward causation” in chemistry, while Stapp (2005) culls evidence from contemporary physics suggesting that there are, contrary to Completeness, causal gaps in the physical world, gaps filled in by the mental (see also Sturgeon 1998; Davies 2006). Emergentists in general deny the principle, either on scientific grounds or by appeal to our conscious experiences of agency (see emergent properties, esp. §4). And although the death of emergentism has been declared more than once on empirical grounds (McLaughlin 1992; Papineau 2000), the view continues to attract philosophers and scientists. (See the contributions to Clayton and Davies 2006; Bedau and Humphreys 2008; Macdonald and Macdonald 2010; Paoletti and Orilia 2017.)