From Shastri and Ajjanagagadde (1990):
Perhaps prompted by the above concerns McCarthy has observed that connectionist systems suffer from "the unary or even propositional fixation" and the representational power of most connectionist systems is restricted to unary predicates applied to a fixed object (see McCarthy's commentary in (Smolensky 1988)). Fodor and Pylyshyn (1988) have also argued at length that the connectionist formulation is inadequate for representing structured knowledge and cannot embody systematicity and compositionality.
- Shastri, L., & Ajjanagadde, V. (1993). From simple associations to systematic reasoning: A connectionist representation of rules, variables and dynamic bindings using temporal synchrony. Behavioral and Brain Sciences, 16(3), 417–451. https://doi.org/10.1017/s0140525x00030910