The Specified Subject Condition (SSC) is a condition proposed in Chomsky (1973) which restricts the application of certain syntactic transformational rules. In many ways it is a counterpart to the Tensed-S Condition (TSC) (proposed in the same paper), applying to non-finite clauses and complex DPs which are not covered by the TSC. The rule was formalized as follows, where a "specified subject" is a lexical subject i.e. a subject with semantic content, like a proper noun, a complex DP, or a pronominal:
Specified Subject Condition (SSC) “No rule can involve X, Y in the structure ... X ... [α... Z ... - WYV ...] ... where Z is the specified subject of WYV in α.” (Chomsky 1973: 239)
The SSC (along with the TSC) therefore had implications for the field which later became known as binding theory. In conjunction with a simple rule of reference (which stipulated that any pronoun following an NP antecedent in the same sentence has disjoint reference with it, the rule applying anywhere unless it is blocked), co-reference is acceptable in the following sentences, because the SSC blocks application of this disjoint reference rule:
(1) The footballersi want [the fans to love themi]
(2) The footballersi laughed at [the fan’s pictures of themi]
The TSC (which essentially blocks transformational and binding rules from applying across clause boundaries) would not block disjoint reference in (1) and (2), hence the need for the SSC. Replacing the pronouns in (1) and (2) with reciprocals shows how the SSC blocks the application of each movement, hence the impossibility of the reciprocals referring back to "The footballers" in (3) and (4):
(3) * The footballersi believe [the supermodel to love each otheri]
(4) * The footballersi laughed at [the supermodel’s pictures of each otheri]
Notice that when the DP-internal subject is removed, each movement is not blocked from applying:
(5) The footballersi laughed at the pictures of each otheri
An empirical problem for the SSC is the failure of disjoint reference to apply in a sentence like (6), where there is no specified subject blocking its application: