A compatibilist likely holds that certain things are up to us, but this does not bear upon the future being metaphysically open. The compatibilist can suppose that something’s being up to someone is a matter of that thing’s being causally dependent on such things as desires or choices or intentions. This brings no difficulty fitting within the confines of a perfectly deterministic world, according to which actions are the causal upshots of such prior mental events and states.
Van Inwagon’s Consequent Argument: If determinism is true, then our acts are the consequence of the laws of nature and events in the remote past. But it is not up to us what went on before we were born, and neither is it up to us what the laws of nature are. Therefore, the consequences of these things (including our present acts) are not up to us.
Presumably, Van Inwagon takes it for granted such things as ‘our acts’ exist; his concern is whether or not theses acts are ‘up to us’ or not. Steward contends that his is the wrong way of looking at the matter. If nothing is up to us, then there are no such things as actions. There are merely reactions, a series of inevitably unfolding events.
Her concept of settling is central. “I want to insist that as I move through the world, performing the various activities of which my life consists, I am constantly settling the answers to a variety of questions whose answers are (therefore) not already settled long before the time at which my actions take place.” The moment of settling is when the agents decides and acts and hence settles the matter in a particular way (p. 39).
“I settle things not only by initiating motor activity but also by continuing it; by refraining, for example, from vetoing the original instruction or from altering it in any of the multifarious ways that are constantly open to me. Because these powers of refrainment and alteration are present throughout the whole duration of the action, I am constantly settling what happens from moment to moment, even if I do not in fact exercise those powers of refrainment and alteration” (p. 46).
Experiments conducted by Libet cast doubt on Steward’s contemporaneous settling, since such experiments suggest that how we shall move is sometimes settled by prior causes of which we have no knowledge. It might be thought that evidence of prior neural activity in advance of a conscious decision suggest the operation of a hidden neural variety of determinism. On Steward’s view, Libet’s evidence is of a readiness potential, a part of the action, but not the necessary cause of the entire action.
“All intentional bodily agency, I suggest, involves the interweaving of conscious systems of bodily control with more basic, effectively automated or partly automated systems. … An enormous amount of the settling that we do as agents is delegated, inevitably, to processes that are ill-described as the causing of motions by mental states, such as choosings, intendings, and the like. … An agent’s settling of things can be perfectly well be constituted by processes to which she pays no mind whatever” (p. 52).
She devotes several pages to the compatibalist Causal Theory of Action that I won't summarize.