In this paper, I give an analysis of the syntax of the antipassive construction in the Eskimo-Aleut language family. In this account, I follow previous works, such as Benua (1997), Basilico (2004, 2012), Aldridge (2012), and Johns and Kučerová (2017) and posit that the antipassive, oblique argument occupies a different position than the transitive, absolutive object. However, I do not argue that the absolutive direct object argument and the oblique antipassive object occupy the same base position. Instead, I analyze the antipassive marker as an element which creates an argument position: it turns the verb to which it is attached from a predicate of events into a relation between an event and an entity, introducing the undergoer thematic role predicate and its argument. By considering that the antipassive morpheme introduces an argument, rather than saturating or demoting one, we explain a number of interesting phenomena: why 'agentive' verbs do not appear with an antipassive morpheme while 'patientive' verbs do, why the antipassive is associated with the inchoative as well as the applicative, and why transitive impersonal verbs do not undergo antipassivization.