Dissertation Abstract 

Vagueness and Ethics

Supervised by Graham Oddie

Vagueness is strange for many reasons. Most strange of all, I think, is that vagueness is at once innocuous to everyday communication, and yet, its destructive philosophic power is awesome. It is well known that vagueness has prompted many philosophers to reject one or more of the following: bi-valence, the Law of Excluded Middle (LEM), the T-schema, the Law of Non-Contradiction, and classical rules of inference—e.g. modus ponens. Vagueness has more than just logical consequences however. For example, building on Lewis (1986), Sider (1997, 2001) argues that composition is unrestricted on the grounds that if it were not, then it would be vague how many things exist, which is impossible. Tye (1996) and Antony (2006) argue that we ought to reject any view according to which it can be vague whether a being is in a conscious state, and that means rejecting both reductive and non-reductive physicalists views consciousness. Further, I argue in this dissertation that on the grounds of vagueness philosophers could plausibly reject of any of the following: Kantian deontology, Utilitarianism, metaethical expressivism, moral naturalism, robust moral realism, the denial of posthumous harm. The list presumably does not stop there. 

This dissertation is entitled Vagueness and Ethics, and its motivating theme is this: If vagueness is going to be used to do so much philosophical damage then not only is it important to have an accurate theory of vagueness, but also we ought to be as careful as possible when making claims about what is vague, especially in the ethical domain. The dissertation is composed of the following essays:

1.     “More or Less Vague” – In this paper, I argue that vagueness admits of degrees and that the standard views of vagueness—vagueness as indeterminacy and epistemicism—cannot satisfactorily accommodate degrees of vagueness.

2.     “Relocating Vagueness” – In this paper, I show that Trenton Merricks’s recent argument against the “vagueness orthodoxy”—the view that vagueness is a feature of language and thought only—reduces to absurdity. 

3.     “Is There Moral Vagueness?” – In the first part of this paper, I argue that the consequences of moral vagueness, if it exists, are even more problematic than has been argued. By “moral vagueness” I mean specifically vagueness as to whether some acts are permissible. I focus on robust moral realism, arguing that no account of moral vagueness—semantic, epistemic, nor ontic—can satisfactorily reconcile with robust moral realism. 

In the second part of this paper, I argue that it is not obvious that moral vagueness exists. I employ a series of tests to cast doubt on whether purported moral Sorites series are actually cases of genuine vagueness, instead of deep moral uncertainty. I defend moral precision from the charge that it is incredible that “permissible” is precise. Finally, motivated by the destructive power for arguments from vagueness, I propose a Vagueness Last approach to purported cases of vagueness. The tests developed in examining purported cases of moral vagueness become tools for implementing a Vagueness Last approach. 

4.     “Posthumous Repugnancy” – In this paper I argue that the possibility of posthumous harm entails what I call Posthumous Repugnancy (PR)—that a person whose wellbeing was extremely high while they were alive could incur small posthumous harms over a long enough period of time after death such that they had a life not worth living. I examine several routes by which the posthumous harm proponent might try and escape posthumous repugnancy, showing each to be highly problematic. I draw a general lesson for desire satisfaction theories of wellbeing. Finally, I consider various vagueness-based objections to my arguments. I draw on strategies developed in my paper, “Is There Moral Vagueness?”, to diffuse those arguments. 



My research in ethics is primarily in axiology, applied ethics, and their intersection. I’m especially interested in the concept of harm, and how different views of wellbeing and harm bear on applied ethical problems. 

Current projects in ethics:

“What Could Be So Bad About Guns?” (paper in progress) – The best hope for justifying gun control is not consequentialism. Rather, it is to identify in guns particular morally relevant features not shared by other dangerous yet relatively unregulated products. I argue the best candidate for that feature is the following asymmetry: Guns make it incredibly easy to do evil, while not making it proportionately easier to do good. Guns make it very easy to deprive others of their rights, while not making proportionately easier to protect others’ rights. Guns share this property with other things we think ought to be heavily controlled, like explosives, but do not share this property with say swimming pools or cigarettes.

“A Better Defense of Abortion” (paper in progress) – The typical rights-based defense of the moral permissibility of abortion focuses on a woman’s right to her own body. I argue that this view faces serious challenges. However, there is stronger case to be made, and it is one that does not suffer from apparent problems with the right-to-body approach. That better approach is to defend abortion on the grounds that a person is not obligated to make large sacrifices or dramatically change their life to accommodate someone else, except under specific circumstances. Being pregnant does not count as being one of those circumstances. I argue that this is the view people often think they are making when they invoke a woman’s right to her body in defending the permissibility of abortion.  


My research in metaphysics primarily concerns vagueness and related issues, as well as philosophical methodology.

Current projects in metaphysics

Most immediately my plan is to develop a more comprehensive account of the Vagueness Last view that I put forward in my dissertation. 

“Is the Knowledge Intuition Reliable?” (psychology study) – Completed is an experimental design for a study which proposes to investigate The Knowledge Intuition, which has a long history but was made famous by Frank Jackson’s “Mary the Color Scientist” thought experiment. Mary’s case is one of a hypothetical cognitive achievement (i.e. whether or not she learned something). This study would test accuracy philosopher’s intuitions about actual cognitive achievement. It is hypothesized that philosophers’ intuitions about actual cognitive achievements will be unreliable. Since intuitions about hypothetical cognitive achievements have the same cognitive etiology as intuitions about actual cognitive achievements, The Knowledge Intuition is therefore unreliable as well.