In this paper, I review how formal features are currently regarded and used in the Minimalist
Program. Although features are the cornerstone in Minimalism, they are used in many different and conflicting
ways. Features may seem particularly relevant to affix-hop because the affix has to be checked
against a higher verb or auxiliary. Chomsky’s (1957) analysis of affix-hop has the affix connected with
an auxiliary, e.g., the -en of have-en, move to a verb on its right, as in have see-en. This analysis is
one of the high points of early generative grammar but, with each new instantiation of the generative
model, it has needed adjustments and the phenomenon is still debated. I will elaborate on a proposal
made in van Gelderen (2013) who argues that interpretable tense, mood, or aspect are in a low position
being probed by the relevant uninterpretable features in a high position. This view I claim is consistent
with data from change and acquisitio