Under standard Phase Theory, the locality constraint deriving successive cyclicity is the PIC (Chomsky 2001), which requires movement to proceed via the edge of phases. For example, a CP phase can only be escaped via Spec,CP. The Williams Cycle (Williams 2003; Poole 2023) generalizes selective opacity, a different kind of locality: It is P’s relative size that makes it opaque to probes that are not sufficiently high in the next lowest clause. For example, probes on C but not on T can search into CP because C T in the functional sequence. Most accounts of selective opacity (Keine 2020) or the Williams Cycle effects (Meadows 2023) handle successive cyclicity and Williams Cycle effects as independent phenomena. That is, a CP may independently necessitate successive cyclicity because it’s a phase and exhibit WC effects because it’s too large.

This talk provides a unified account that derives successive cyclicity and Williams Cycle effects. Specifically, I introduce a novel constraint, which dictates movement steps must proceed along well-formed fseq-fragments, i.e. must be turned into steps that are clause-internal in the relevant sense. Cross-clausal movement can proceed via two strategies. My account predicts that the first strategy, successive cyclic sub-extraction obviates Williams Cycle effects because movement from the embedded clause’s edge is free to the matrix clause (e.g. in Mongolian (Fong, 2019) and P’urhepecha clauses (Zyman, 2017)). If sub-extraction cannot proceed successive cyclically from a clause (e.g. German or Hindi CPs), sub-extraction can still proceed via an alternative strategy: The clause moves to an equal-sized matrix projection. Since the clause’s movement is delayed till the matrix clause reaches the size of the embedded clause, clauses requiring extraposition for transparency will exhibit Williams Cycle effects.