Weak particularism about reasons is the view that the normative valency of some descriptive considerations varies, while others have an invariant normative valency. A defence of this view needs to respond to arguments that a consideration cannot count in favour of any action unless it counts in favour of every action. But it cannot resort to a global holism about reasons, if it claims that there are some examples of invariant valency. This paper argues for weak particularism, and presents a framework for understanding the relationships between practical reasons. A central part of this framework is the idea that there is an important kind of reason—a ‘presumptive reason’—which need not be conclusive, but which is neither pro tanto nor prima facie.