When we are thinking about what we ought to do, we are nearly always deciding among options. And we often talk in ways that reflect this; statements about what one ought to do are frequently explicitly statements that identify some act as the one to be performed from a broader set of alternatives. Accordingly, we recognize that a consideration that favors one act among one set of options might favor a different act among a different set of options. This has led some to think that normative reasons are fundamentally contrastive in structure. This is to say that a reason to perform some act is always a reason to perform that act rather than some other act. Contrastivism about normative reasons is the view according to which there is no reason simpliciter to perform a given act; a reason to perform some act A is always a reason to A given some background of alternatives. As it captures the general structure of normative reasoning, contrastivism sounds intuitive. But a lot of work needs doing in order to flesh out the details.
In Contrastive Reasons (Oxford University Press, 2017), Justin Snedegar develops and defends a novel version of contrastivism about moral reasons. He then extends the view to normative reasons of other kinds by offering an analysis of when it is rational to withhold belief.