FSC holds that all computation manipulates formal syntactic items, without regard to any semantic properties those items may have.  Precise formulations of FSC vary. Computation is said to be “sensitive” to syntax but not semantics, or to have “access” only to syntactic properties, or to operate “in virtue” of syntactic rather than semantic properties, or to be impacted by semantic properties only as “mediated” by syntactic properties. It is not always so clear what these formulations mean or whether they are equivalent to one another. But the intuitive picture is that syntactic properties have causal/explanatory primacy over semantic properties in driving computation forward.