the idea introduced in (23d) is of particular importance as a single dp/np-chain can acquire more than one θ-role by simultaneously satisfying the θ-criterion across multiple positions, e.g. the subject of the non-finite embedded clause and the subject of the matrix verb. in this context a chain refers to an argument which has moved and all of its traces. hornstein argues that there is insufficient empirical evidence that a chain must be restricted to a single θ-role and that allowing multiple θ-roles per chain is the null hypothesis.