We propose a characterization of language that does not rest on the hypothesis that meaning is necessarily shared across interlocutors, since it is fundamentally grounded in the privacy and subjectivity of mental content. We first argue that the function of language is thus best characterized as the coordination rather than the communication between minds, since it is the constraints on use—rather than on meaning itself —that are negotiated between interlocutors during linguistic interactions. We then explore the evolutionary benefits of subjectivity and argue that it positively contributes to adaptability through: 1) innovation, as conceptual variability at the individual level increases the likelihood of the group of finding relevant conceptual innovations when exposed to environmental challenges; and 2) transfer, as subjective coordination allows for individual innovations to spread across a whole population, without individuals having to align their conceptual spaces and thereby lose the benefits of conceptual variability