Silvan Wittwer

Recently, Tomas Bogardus (2016), Andreas Mogensen (2017) and – at least on one plausible reconstruction – Sharon Street (2005) have argued that evolutionary theory debunks our moral beliefs by providing higher-order evidence of error. In response, moral realists such as Katia Vavova (2014) have objected that such evolutionary debunking arguments are self-defeating. The literature lacks any discussion of whether this self-defeat objection can be handled. My overall aim is to argue that it cannot, thus filling that lacuna – and vindicating Vavova’s worry. To achieve my aim, I proceed in two steps. First, I propose a novel, prima facie promising strategy for avoiding self-defeat: evolutionary debunkers should reject Conciliationism, as defended by David Christensen (2007, 2009, 2011) and others, and instead explore Thomas Kelly’s (2010) Total Evidence View as their background view on the epistemic significance of higher-order evidence of error. Then, I show that evolutionary debunkers face insuperable difficulties trying to successfully implement that strategy. Depending on the kind of higher-order evidence of error that evolutionary considerations putatively provide, they either struggle with evidential weight or are committed to inconsistent assumptions about evolutionary counterparts. Either way, the evolutionary debunking argument from higher-order evidence of error fails.

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.

This PhD thesis provides an extended evaluation of evolutionary debunking arguments in meta-ethics. Such arguments attempt to show that evolutionary theory, together with a commitment to robust moral objectivity, lead to moral scepticism: the implausible view that we lack moral knowledge or that our moral beliefs are never justified (e.g. Joyce 2006, Street 2005, Kahane 2011). To establish that, these arguments rely on certain epistemic principles. But most of the epistemic principles appealed to in the literature on evolutionary debunking arguments are imprecise, confused or simply implausible. My PhD aims to rectify that. Informed by debates in cutting-edge contemporary epistemology, Chapter 1 distinguishes three general, independently motivated principles that, combined with evolution, seem to render knowledge of robustly objective moral facts problematic. These epistemic principles state that (i.) our getting facts often right in a given domain requires explanation – and if we cannot provide one, our beliefs about that domain are unjustified; (ii.) higher-order evidence of error undermines justification; and (iii.) for our beliefs to be justified, our having them must be best explained by the facts they are about. Chapters 2-4 develop and critically assess evolutionary debunking arguments based on those principles, showing that only the one inspired by (iii.) succeeds. Chapter 2 investigates the argument that evolution makes explaining why we get moral facts often right impossible. I argue that Justin Clarke-Doane’s recent response (2014, 2015, 2016, 2017) works, yet neglects an issue about epistemic luck that spells trouble for robust moral objectivity. Chapter 3 discusses the argument that evolution provides higher-order evidence of error regarding belief in robustly objective moral facts. I show that such an argument falls prey to Katia Vavova’s (2014) self-defeat objection, even if evolutionary debunkers tweak their background view on the epistemic significance of higher-order evidence. Chapter 4 develops the argument that evolution, rather than robustly objective moral facts, best explains why we hold our moral beliefs. I offer a systematic, comprehensive defence of that argument against Andreas Mogensen’s (2015) charge of explanatory levels confusion, Terrence Cuneo’s (2007) companion in guilt strategy, and David Enoch’s (2012, 2016) appeal to deliberative indispensability. Chapter 5 brings everything together. It investigates whether robust moral objectivity survives the worry about epistemic luck raised in Chapter 2 and the explanatory challenge developed in Chapter 4. Making progress, however, requires a better idea of how we form true, justified beliefs about and acquire knowledge of robustly objective moral facts. Since it offers the most popular and best-developed epistemology of robustly objective morality, my inquiry in Chapter 5 focuses on contemporary moral intuitionism: the view that moral intuitions can be the source of basic moral knowledge. I argue that its success is mixed. While moral intuitionism has the conceptual tools to tackle the problem of epistemic luck from Chapter 2, it cannot insulate knowledge of robustly objective moral facts against the sceptical worry raised by the evolutionary debunking argument developed in Chapter 4. Thus, evolutionary theory, together with a commitment to robust moral objectivity, does lead to a form of unacceptable moral scepticism.

In my essay, I will argue that evolution does not undermine naturalism. This is because Alvin Plantinga’s evolutionary argument against naturalism rests on a false and unmotivated premise and is thus invalid. My argument consists of two parts: In the expository part, I outline Plantinga’s evolutionary argument against naturalism in considerable detail (section 2). In the argumentative part, I firstly pose William Ramsey’s challenge to Plantinga’s probabilistic claim that the reliability of human cognitive faculties is low and critically examine Plantinga’s response in order to reinforce it (section 3). Secondly, I attack Plantinga’s understanding of human evolution, which motivates his cognitive skepticism, as being unduly narrow (section 4).