1. Either there are some physical things X, or everything is nonphysical.
2. Assume that there are some physical things X. For whatever y, add y to X if y resembles some member or members of X via a Wittgensteinian family resemblance.
3. Whatever is left out in the end is nonphysical.
4. Physicalism says nothing is left out.
(Is the substrate physical or nonphysical, or a mixture? Those arguing for a mixture have the burden of distinguishing one from the other, whereas for physicalists this burden is lifted.)