The Ethics of Treaties: A Humean Account

This thesis concerns the reasons that states have to comply with their treaty commitments. It aims to answer two questions. Firstly, what reason does signing a treaty give to a state to act in accordance with the treaty? Secondly, assuming that there is such a reason, how does entering into a treaty generate that reason?  One answer to these questions is to say that treaties are kinds of promises between states. To enter into a treaty is to make a promise and promises should be kept. But promises are a puzzling way of generating reasons for action. It is not clear how it is possible to create a reason to do something merely by communicating an intention to create a reason. So, to say that treaties are promises seems merely to transpose this puzzle from the relations between individual persons to international affairs and the relations between states.  In this thesis I endorse a view of treaty making that understands treaties as promises as the philosopher David Hume understands them. I argue that this provides a plausible account of treaty making. I suggest that the resulting view, which I label ‘Treaty as Humean Promise,’ provides plausible and appealing answers to the two questions mentioned above.  Treaty as Humean Promise claims that states entering treaties create self-interested reasons to comply with those treaties. They do this by invoking an independent social convention of treaty making one of the rules of which is that treaties must be kept. Continued access to this social convention is important to states. They jeopardise this continued access by violating their treaties and giving their treaty partners, and potential treaty partners, reason to withdraw future trust in them. I set this out in chapters 1 and 2. In chapter 3 I claim that Treaty as Humean Promise can make sense of the intuition that there are moral reasons to comply with treaties. In chapter 4 I look at what Treaty as Humean Promise has to say about different types of treaty.  In chapters 5 and 6 I discuss Hume’s own views on treaty making. I offer a charitable reading of some puzzling remarks by Hume from a section of A Treatise of Human Nature called ‘Of the laws of nations’. In doing so, I defend Hume against a number of his critics.  In the final two chapters I discuss a ‘political realist’ account of treaties. I distinguish between ‘act’ and ‘rule’ variants of political realism. Political realists, I suggest, should be rule realists at least about treaties. This means that they should endorse and follow the rule that treaties should be kept all else being equal.