 Both fundamental physical and special-scientific posits and laws appear to be characterized, at least in part, in determinable terms. As Armstrong (1997) and French (2014) observe, it is natural to see fundamental physical laws as relating determinables, such as mass and charge, or to themselves be determinable  relations.[14]  And in the special sciences, for example, the features of molecules relevant to chemical interactions abstract from the precise details of atomic position and momentum, and features of thermodynamic systems near critical points abstract from compositional and other micro-level details (see Batterman 1998). More generally, the posit of existing and irreducible determinables in both fundamental and special sciences is in line with a principle of explanation pervasive in the sciences, according to which good explanations do not cite unnecessary details (see, e.g., Strevens  2004).[15] 