 In addition, set theorists usually formulate their theory in terms assuming atomism, yet it seems possible that there is gunky non-atomic stuff (Zimmerman 1995, §9, 1996b; Sider 1993). If there are, or could be, stuffs like this, then standard set-theoretic treatments will not work, since such theories require all sets to be well-founded. Another problem is that for some stuffs it is (or seems to be) indeterminate what, if anything, will count as a smallest unit of it—e.g., minestrone soup or beer. So, the set theorist has a problem with non-atomic or fuzzy atomless stuffs (see  1.4  for terminology). In what immediately follows, we will only discuss the issue of non-atomicity.