Reason fundamentalism and what is wrong with it

Is there a fundamental feature of normativity, to which other features can be reduced? One defensible view is ‘reason fundamentalism’: that the fundamental feature is the relation that holds between a person and F-ing when the person has reason to F. (‘F’ stands for any verb phrase, such as ‘run for the bus’ or ‘hope for relief’ or ‘believe Kampala is in Ghana’.) Another defensible view is ‘ought fundamentalism’: that the fundamental feature is the relation that holds between a person and F-ing when the person ought to F. The popular view that the fundamental feature of normativity is the property of being a reason is not defensible, since that property can be reduced to either of the two relations I have just described. I argue that ought fundamentalism is more credible that reason fundamentalism because it is more faithful to our ordinary normative concepts.