Recently, companions in guilt strategies have garnered significant philosophical attention as a response to arguments for moral error theory, the view that there are no moral facts and that our moral beliefs are thus systematically mistaken. According to Cuneo (The normative web: an argument for moral realism, Oxford University Press, Oxford, 2007), Das (Philos Q 66:152–160, 2016; Australas J Philos 95(1):58–69, 2017), Rowland (J Ethics Soc Philos 7(1):1–24, 2012; Philos Q 66:161–171, 2016) and others, epistemic facts would be just as (...) metaphysically problematic (or ‘guilty’) as moral facts. But since epistemic error theory is implausible, arguments for moral error theory prove too much and should be rejected. My aim is to argue that the success of this strategy is limited. In particular, the companions in guilt response fails against error-theoretic arguments motivated by concerns about explanatory dispensability, as recently developed by Joyce (The evolution of morality, MIT press, Bradford, 2005) and Olson (Moral error theory: history, critique, defence, Oxford University Press, Oxford, 2014: Ch. 7). To succeed, the response would require a prima facie plausible argument to the effect that epistemic facts are metaphysically dubious because they, too, are explanatorily dispensable. But, as I show, any such argument proves self-effacing: its premise commits us to believing in epistemic facts, while its conclusion forces us to deny their existence. Consequently, companions in guilt strategies don’t offer a panacea against arguments for moral error theory. (shrink)

Metaethical debunking arguments often conclude that no moral belief is epistemically justified. Early versions of such arguments largely relied on metaphors and analogies and left the epistemology of debunking underspecified. Debunkers have since come to take on substantial and broad-ranging epistemological commitments. The plausibility of metaethical debunking has thereby become entangled in thorny epistemological issues. In this thesis, I provide a critical yet sympathetic evaluation of the prospects and challenges facing such arguments in light of this development. In doing so, (...) I address the following central question: how could genealogical information undermine the epistemic justification of moral beliefs? In Part I, I begin answering the central question by extracting explicit and implicit epistemic principles from three popular debunking arguments. These arguments, due to Gilbert Harman, Richard Joyce, and Sharon Street, generate principles concerning ontological parsimony, explanatory dispensability, epistemic insensitivity, lack of epistemic safety, unexplained reliability, epistemic coincidences, and explanatory constraints on rational belief. Having set out the principles tasked with explaining how genealogical information undermines, Part II of the thesis seeks to evaluate whether debunking arguments built on them succeed. To this end, I consider two types of challenges faced by such arguments. First, there are strategies that attempt to block global moral debunking arguments. I argue that one popular such strategy, the so-called ‘third-factor strategy’, has been misunderstood. When understood correctly, it is of no help in answering debunking arguments. I then flesh out an alternative and more promising strategy for blocking such arguments. I then turn to internal challenges facing debunkers, particularly those who rely on ‘explanationist’ principles. I argue that explanationist debunking arguments, as well as most others, fall prey to one or more of four internal challenges: the implausibility of first-order epistemic principles, the threat of overgeneralization, the threat of self-defeat, and the need for costly metaepistemic commitments. I conclude that current debunking arguments fail to establish that no moral belief is justified. By analyzing why existing arguments fail, I develop two conditions of adequacy that debunkers must satisfy in order to navigate the internal challenges successfully. I end by suggesting future directions that debunkers should pursue to rehabilitate the prospects for global moral debunking arguments. (shrink)