  Of those who have argued that threats and offers can both be used coercively, David Zimmerman has been most prominent (Zimmerman 1981; others who have argued offers can coerce include Frankfurt 1988 [1973]; Held 1972; Lyons 1975; Van De Veer 1979; Benditt 1979; Feinberg 1986; Stevens 1988; for criticism of Zimmerman, Held, and Stevens, see Alexander 1981; Bayles 1974; and Swanton 1989, respectively). Retaining the baseline-approach to coercion found in Nozick, Zimmerman urges that in setting a baseline for judging a proposal, we should take into account the possibility that the proposal maker is actively hindering the coercee from obtaining a situation for herself that would be better than the situation the coercer proposes. So, for instance, if a person is destitute on an island, and someone proposes to employ this person for a life-sustaining pittance, this proposal may count as an offer, since it is an improvement over the “pre-proposal” situation. But if the person is destitute and unable to obtain better conditions only because the employer actively prevents the person from leaving the island (say, by preventing the building of boats), Zimmerman suggests the offer should be regarded as coercive.  That's because the appropriate baseline for evaluating the proposal is the state of affairs that the recipient would face in the absence of special interference by the proposal maker. (In the present case, this might be the situation the island inhabitant would face were she able to build a boat and return to the mainland.) If relative to this baseline the offer is less favored, then it should count as coercive, Zimmerman thinks.