The Scope and Limits of Debunking Arguments in Ethics

Abstract

Debunking arguments use empirical evidence about our moral beliefs - in particular, about their causal origins, or about how they depend on various causes - in order to reach an epistemic conclusion about the trustworthiness of such beliefs. In this thesis, I investigate the scope and limits of debunking arguments, and their implications for what we should believe about morality. I argue that debunking arguments can in principle work - they are based on plausible epistemic premises, and at least some of them avoid putative problems concerning regress and redundancy. However, I also argue that some debunking arguments fall short because they are insufficiently supported by the empirical evidence. By considering different objections, analyses, and a case study, I explore the conditions for a successful debunking argument.

Chapter 1 starts by providing an overview of debunking arguments - their structure, their variations, and common objections to them. Chapter 2 defends debunking arguments against counterexamples to their epistemic premises - counterexamples which, if effective, will show that debunking arguments cannot work in principle. I argue against the use of these counterexamples, and contend that we cannot merely deny the epistemic premises of a debunking argument. Chapter 3 defends debunking arguments against three further objections concerning how such arguments fit into the web of beliefs. The regress objection contends that debunking arguments make assumptions that commit us to a problematic regress. The findings redundancy objection contends that the empirical findings are unnecessary in a debunking argument. The argument redundancy objection alleges that debunking arguments assume what they set out to prove.

Even if debunking arguments are in principle viable, some of them still fail because of poor empirical support. Chapter 4 argues that some global, evolutionary debunking arguments fall short - roughly because we are poorly placed to observe, intervene on, and predict what would happen from different evolutionary causes. In contrast, experimental evidence from moral psychology and behavioural economics will be better placed to support a debunking argument. Chapter 5 considers a novel debunking argument based on evidence of this kind - which shows how we overweight low probabilities in our decision-making, and underweight moderate to high probabilities. I explore debunking and vindicating arguments concerning our intuitions about risky aid. Chapter 6 proposes a Bayesian analysis of debunking arguments, which can guide us in revising our beliefs in response to debunking. I highlight further conditions for debunking to work, and propose a quantitative method for integrating different kinds of evidence in order to arrive at a rational credence about morality in light of debunking.