Ethics 101: To Be or Not To Be?

Foreword

Questions like “Why be moral?” or “What do we mean when we say something or someone is morally bad?” have been protractedly debated within the philosophical tradition. This series gives an overview of the traditional and contemporary discussion on the topic of Ethics and morality by focusing on the philosophical foundations of the moral phenomenon and the most relevant schools of thought trying to answer the question: “What should I do?”. Whether in assessing other people’s actions or our own, moral questions are part of our daily lives; their answers shape how we behave and expect others to behave. Thus, giving a philosophical and systematic answer to these questions gains relevance beyond the mere sphere of academic circles. The series explores how the moral question is not just about “good” or “bad” but also about what type of life we want to live and how we advocate for a world that reflects such life choices. The articles will present arguments for and against different schools of thought, showing different ways of behaving and thinking in everyday life according to those theories. Readers are expected to interiorize terminology and the conceptual depth of the development of ethical theory.

Ethics 101 is divided into six articles:

1. Ethics 101: To Be or Not To Be?

2. Ethics 101: Reasons to Be Good.

3. Ethics 101: Follow the Rules.

4. Ethics 101: It Is All about the Consequences.

5. Ethics 101: Virtue over Goodness.

6. Ethics 101: Are We More Moral Than Before?

Introduction

Part of the nature of philosophical thought lies in giving answers to apparently unanswerable questions. What makes philosophy such an engaging discipline is the constant inquiry of what we tend to consider as sure and certain, challenging our most rooted intuitions. The philosophical method that carries out this questioning task to the limit is the one of scepticism. Its aim is, through thorough reasoning, to shake the foundations of our knowledge. A sceptical method of inquiry has been used in several areas of philosophical thought. From doubting our everyday perceptions to mistrusting the objectivity of what we define as reality, scepticism puts our capacity to give solid foundations to our reality to its limits.

This article will develop sceptic ideas focused on the topic of morality. Questions regarding the objectivity of the moral phenomenon and its importance in our lives and daily actions will be assessed from a philosophical perspective. Since the topic of scepticism is so vast and extensive, this article will focus on the most general sceptical theories about morality. The first section will focus on a general explanation of scepticism and how it aims to question our knowledge. The second section puts forward general considerations, some of them not exclusively philosophical in nature, in favour of a sceptical view about the phenomenon of morality. The third section will be dedicated to explaining moral scepticism in its epistemological dimensions, i.e. the idea that there is no such thing as “moral knowledge”. Finally, the last section will cover scepticism regarding moral motivation by exploring the question, “Why should we act morally?”.

Figure 1: "Morals" (Mellon, 2018).

Scepticism

Before dwelling on moral scepticism, it is important to understand scepticism's general roots and development as it has been an important philosophical position since antiquity. As noted by Katja Vogt (2022), the sceptic movement began as early as the third century BCE, and it included philosophers such as Pyrrho, Sextus Empiricus, Arcesilaus, and Carneades, among others. The main concern of the sceptics of antiquity was dealing with questions about belief, knowledge, and truth. Typical sceptical questions could include “How do we know that we know something?” or “What do we mean when we say that something is 'true'?”

Due to the nature of these questions, sceptical schools of thought are generally considered to be eminently epistemological, i.e. they deal with questions regarding knowledge and its possibility. The development of Western philosophy and its particular modes of finding explanations for natural or human phenomena led to an extension of the philosophical question. Our justification for holding the beliefs we possess and the strength of those beliefs for giving us knowledge was put into question by sceptics in an attempt to examine propositions that we ordinarily think we know. How do I know, for example, whether the table that I see in front of me is really there? How do I know that the room I find myself in is not the product of an elaborate scheme to keep me prisoner, as was the case for Neo in The Matrix? These questions are eminently sceptical because they intend to show, through reasoned argument, that we may not be justified in believing what we ordinarily believe to be true. They question that we cannot really know what we think we know.

Within the philosophical discussion, as noted by Matthias Steup (1996) and Roderick Chisholm (1966), among many others, talking about knowledge implies talking about beliefs. The fact that I know that the Eiffel Tower is located in Paris means that I hold the belief that it is and that I have reasons to have that belief. What makes my belief knowledge, additionally, is the fact that such belief is true; there is an alignment between my reasons to hold my belief, the belief itself, and reality. The typical modern sceptical analysis pays attention to our use of propositions. In philosophy, a proposition is generally understood as the content of an assertive or declarative sentence. For example, if I express the sentence “today is a sunny day”, the proposition of that sentence is the content or meaning of it, i.e. that today is a sunny day. As a consequence, in philosophy, we do not say that a sentence is true if today is a sunny day but that the proposition is. 

For the sceptic, my utterance of the phrase “there is alien life on the dark side of the moon” would not constitute a proposition of knowledge if I do not hold the belief that there is life on the dark side of the moon, even if that fact was true. The reason for this is that “wild guesses” are not propositions of knowledge. For it to be knowledge, it is necessary to believe that there is life on the dark side of the moon; those beliefs must be justified, and there must be, in reality, life on the dark side of the moon. Sceptics question our reliability on some of the steps in the chain that leads us to hold knowledge. Either questioning our justification for the beliefs we hold or questioning knowledge itself, this line of philosophical inquiry shakes our epistemological foundations.

Figure 2: "Pillar of Doubt" (Charles, 2016).

Following the work of Juan Comesaña (2019), we can categorise scepticism into two main forms differing from one another in the intensity of the claims they hold. Comesaña argues we can hold three attitudes toward a proposition, depending on whether we are justified in believing its truth. Let us think again about the proposition “there is alien life on the dark side of the moon”. If we do not have justification for believing it, then the attitude we can adopt is of disbelief; on the contrary, if we are justified, we adopt the attitude of belief. We can also consider that regarding belief and disbelief, we may, under certain circumstances, lack justification for holding any of the two. If I am not justified in believing or disbelieving that there is life on the dark side of the moon, then there is a third philosophical attitude to adopt: the one of suspending judgment. Naturally, we may not always be in a position to adopt such an attitude. If I am told that Paris is the capital of France, I do have enough justification to believe it. Therefore, the attitude of suspension of judgment is not justified, and I cannot adopt it (Comesaña, 2019). For the general sceptic, the only justified attitude to hold regarding the proposition of knowledge is the suspension of judgment. 

With these three attitudes in mind, we can divide scepticism into two main types. One denies that we can justifiably hold any belief or disbelief, and the only justified attitude to adopt towards a proposition like the one presented above is the suspension of judgment. The other denies that we are justified in holding beliefs or disbeliefs except for the belief that we are not justified in holding beliefs. These two types of philosophical scepticism are called Cartesian (due to their association with the French Philosopher Rene Descartes), also called dogmatic, and Pyrrhonian, respectively. In order to understand the difference between the two, it is important to consider that the three types of attitudes towards propositions asserting knowledge can also be adopted towards the proposition asserting that the only justified attitude is the one of suspending judgment. In other words, the attitudes toward propositions can be adopted towards second-order propositions, i.e. propositions about the attitudes towards propositions. Thus, the difference between the two types of scepticism lies in the strength of their claims while applying the sceptic attitude of suspension of judgment. Cartesian scepticism adopts the belief that the only justified attitude towards a proposition is to suspend judgment; this means that they do not necessarily apply the sceptic principle of suspension of judgment to the second-order proposition that suspension of judgment is the only attitude to adopt towards any proposition. In other words, we are justified in believing that we should suspend judgment. Pyrrhonian sceptics, on the other hand, maintain the suspension of judgment towards any type of proposition, including the second-order ones. To put it in another way, Cartesian Skepticism selectively applies scepticism within defined fields and includes a meta-belief about the justification of suspension of judgment. Pyrrhonian Skepticism embraces a universal scepticism without necessarily committing to meta-level beliefs, advocating for a comprehensive suspension of judgment.

Why Be Sceptical?

In our everyday lives, we may ask ourselves why we should act in a certain way. Some of these thoughts translate into considerations, subject to philosophical scrutiny, about why the moral phenomenon is important. Asking these questions is useful because they can present strong reasons in favour of philosophical scepticism. This is particularly important because even in light of possible refutation to sceptical arguments, motivations for doubting the moral phenomenon in any of its dimensions ought to be regarded if we want to erect strong philosophical and theoretical foundations for it. Furthermore, the nature of morality, diverse from other types of phenomena, is more susceptible to questioning. This susceptibility is due to the lack of immediacy of the phenomenon itself. Moral facts cannot, for example, be perceived by our senses. Therefore, the possibility of us acquiring knowledge about morality can more easily be put into question. The general considerations in favour of moral scepticism have been thoroughly presented by John Leslie Mackie (1977) in one of his most influential works on ethics. Mackie states that:

The considerations that favour moral scepticism are: first, the relativity or variability of some important starting points of moral thinking and their apparent dependence on actual ways of life; secondly, the metaphysical peculiarity of the supposed objective values, in that they would have to be intrinsically action-guiding and motivating; thirdly, the problem of how such values could be consequential or supervenient upon natural features; fourthly, the corresponding epistemological difficulty of accounting for our knowledge of value entities or features and of their links with the features on which they would be consequential; fifthly, the possibility of explaining, in terms of several different patterns of objectification, traces of which remain in moral language and moral concepts, how even if there were no such objective values people not only might have come to suppose that there are but also might persist firmly in that belief. (Mackie, 1977, p. 42)

We will refer to these five considerations presented by Mackie, following the works of Walter Sinnot-Armstrong (2019) and Diego Machucha (2018) in the following ways: moral disagreement, the peculiarity of morality, natural dependence from the moral phenomenon (also called the problem of supervenience), moral knowledge, and moral explanation in the absence of moral values. In what follows, I will proceed to explain the reasoning behind these considerations.

Figure 3: "Philosopher in Meditation" (Rembrandt, 1632).

The first consideration derives from the observable fact that individuals hold conflicting views on the moral permissibility of various issues. Abortion, capital punishment, and hurting certain types of animals are some examples of this. Based on these disparities, it is tempting to conclude that no universally accepted moral claim exists. Therefore, the sceptic view presents that we have reasons to doubt the content of the moral phenomenon and our knowledge of it. Nevertheless, these disputes do not automatically negate the possibility of consensus on other moral principles. Even if disagreements persist, they don't necessarily invalidate my own moral beliefs (Sinnot-Armstrong, 2019, p. 12).  There is a potential for resolution through persuasion or improved circumstances, such as increased knowledge and impartiality. The existence of moral disagreement, although conducive to the questioning of the objectivity of morality, does not rationally imply the negation of the moral phenomenon itself. Furthermore, in a similar way that discrepancies regarding visual illusions do not eliminate the existence of the drawing itself, disagreement regarding morality does not automatically deny the existence of the phenomenon or of its possible objectivity. What could be deducted from this type of disagreement is that the nature of morality differs from other types of phenomena in the human experience. As a consequence, moral disagreement serves as a consideration for moral scepticism, but it does not imply a complete refutation.

The arguments regarding the peculiarity of morality, the one of dependency, and the one regarding knowledge are strongly related to one another. They focus on the perceived strangeness of certain aspects of morality. These arguments, originally posed by Mackie, consist of two parts, one metaphysical and the other epistemological. He posits that if objective values existed, they would be exceptionally peculiar entities, qualities, or relations, fundamentally distinct from anything else in the universe (Mackie, 1977, p. 34). Moreover, the strangeness of the phenomenon does not just lie in the particularity of its nature. It remains to be explained how natural phenomena, such as material facts, interact and acquire certain properties (like being good or bad) from moral facts. Awareness of these moral facts or values in nature would necessitate a unique moral perception or intuition, unlike our ordinary means of understanding other phenomena. Mackie identifies four distinctive elements of morality that make it peculiar: the inherently action-guiding and motivating nature of alleged objective moral facts, i.e. the characteristic that moral facts have of moving individuals to behave in certain ways, the dependency of natural facts on moral ones, and the knowledge of both objective moral facts and their links with natural ones. In a nutshell, the peculiarity of morality is that if moral facts exist, they must be somehow related to material facts because they motivate individuals to act (or not to act) in determinate ways. Therefore, if we want to understand morality, we need to understand these connections. Considering these peculiarities of the moral phenomenon, these considerations imply that there must be a simpler way for us to explain what morality is without the need to understand a world in which strange will-motivating facts exist. A simpler explanation, for example, is to deny the existence of moral values as objective elements in the world and recognise them as projections of subjective responses to natural facts, a philosophical position that will be explained below.

The last and fifth consideration in favour of moral scepticism also relates to the possibility of a better explanation. Even if we deny that there are moral facts or objective moral values that we can know and adopt in our everyday lives, there is yet another way of explaining the fact that we believe and act as if they existed. One of these explanations, and probably the most famous one, is the argument from evolution. Following Machucha, the argument from evolution heavily draws on the insights of evolutionary biologists. It presents that the most plausible explanation for the origin of morality involves evolution. According to this perspective, natural selection has shaped faculties or capacities dedicated to moral judgment. The evolutionary account challenges our first-order moral beliefs by asserting that morality does not need to be true; rather, it just needs to be evolutionarily advantageous for us to believe it is true. The study of evolutionary arguments for moral scepticism, exploring the idea that biological evolution aims at adaptive rather than truth-tracking moral belief-forming processes, has gained considerable attention in metaethics (Machucha, 2018, p. 14-15). These arguments suggest that evolutionary processes don't necessarily aim at forming reliable moral beliefs that are true; instead, they focus on beliefs that are adaptive for survival and reproduction. This implies that humans are predisposed to make moral judgments irrespective of the evidence for or against the existence of objective moral facts.

While some might argue that adaptive processes must be reliable, supporting the idea that moral judgments are evolutionarily useful because they are generally true, the sceptics propose that even if moral beliefs are adaptively helpful, it doesn't necessarily mean they are true. Evolutionary sceptical arguments are generally understood to provide an undercutting defeater for moral beliefs, asserting that they are not formed in a reliable way and are not epistemically justified. 

Figure 4: "Stańczyk" (Matejko, 1862).

Do We Have Moral Knowledge?

Now that some of the reasons in support of scepticism have been presented, it is time to explain what sceptical views have to say about the moral phenomenon. As presented above, the main type of scepticism is epistemological. It doubts the possibility of knowledge by questioning the proper justification of our beliefs. In this sense, it seems natural that this philosophical doctrine, applied to ethical theory, challenges the foundation of our ethical knowledge. Nevertheless, the different sceptical arguments presented in the case of ethics are not purely epistemological, for they additionally question different aspects of the ethical dimension. Thus, the nuanced nature of these sceptical arguments makes them closely related to one another, requiring that we pay special attention to them separately. 

The case for epistemological moral scepticism follows the same rationale as what has been presented thus far: they deny the possibility of moral knowledge. This type of philosophical argument follows the same distinction between Cartesian and Pyrrhonian scepticism. Following Walter Sinnott-Armstrong (2019), Pyrrhonian sceptics regarding moral knowledge reject the idea that people can know the truth of any substantive moral belief, expressing doubt about the possibility of moral knowledge. They refrain from asserting that moral knowledge is definitively impossible, maintaining extreme doubt without making conclusive claims. This scepticism extends to justified moral belief, with Pyrrhonian sceptics withholding judgment about the possibility of any justified moral belief.

On the other hand, dogmatic moral sceptics adopt a more assertive stance on the epistemic status of moral beliefs. They claim that nobody ever knows the truth of any substantive moral belief, and some extend this assertion to include justified moral belief, arguing that nobody is ever justified in holding such beliefs. 

The relationship between the claims of scepticism about moral knowledge and justified moral belief hinges on the nature of knowledge. If knowledge is understood to imply justified belief, scepticism about justified moral belief implies scepticism about moral knowledge. However, even if knowledge requires justified belief, it does not exclusively demand it. Therefore, scepticism about moral knowledge does not necessarily entail scepticism about justified moral belief. This distinction arises from the understanding that knowledge implies truth, whereas justified belief does not. Consequently, if moral beliefs cannot be true, they may still be justified in a manner independent of truth, even if they will never be known as true (Sinnot-Armstrong, 2019).

An important aspect to highlight in the description of epistemological moral scepticism, as mentioned by Machuca (2018), is how the questioning of moral knowledge occurs. Moral knowledge is different in nature from knowledge of facts. While I can be justified in believing that there is a table in front of me or that Paris is the capital of France, how am I justified in believing that torturing somebody just for pleasure is morally bad? Or even further, how do I know if there is such a thing as a “moral fact”? Evidently, whatever moral truths are about are different from physical or material facts. We do not have sensorial access to moral facts. Therefore, Machucha argues, the sceptic about moral knowledge may not just ask whether we are justified in believing a moral fact but also should question how we have cognitive access to those facts. 

Figure 5: "Saturn Devouring His Son" (Goya, 1820-1823).

Why Be Moral?

The sceptical question that asks for reasons to be moral is commonly known as practical moral scepticism. In one way or another, many of us have asked others or ourselves in the course of our lives: "What motivates one to act morally?" Even though the formulation of the question seems rather simple, it still requires further elaboration. For this, it is useful to follow Sinnot-Armstrong’s analysis.

Firstly, the question implies the search for a reason behind our moral actions. Some philosophers assert that all reasons are inherently self-interested. Thus, the query "Why be moral?" essentially asks, "Why is it in my self-interest to be moral?". Conversely, others contend that certain reasons pertain to the consequences for others or may not relate to any effects on anyone. In this case, "Why be moral?" extends beyond personal interest to inquire about the rationality of immorality or what prevents it from being irrational to be moral (Sinnot-Armstrong, 2019).

In the second part of the question, we find the expression "be moral." The question "Why be moral?" might be interpreted as "Why should I embody moral virtues?". The question is not merely about actions that can be catalogued as “moral” but about a way of being. This distinction is important in light of the fact that there are instances where there is no apparent reason to refrain from a specific immoral act, but there is still a reason to oppose a broader tendency towards immorality. In other words, there might not be strong reasons to behave immorally in a specific moment x, but reasons may be strong to oppose sustained immoral behaviour. Even if reasons refer exclusively to self-interest, widespread tendencies toward immorality might always pose a threat to the agent's self-interest, providing a perpetual reason to avoid being an immoral person. Practical moral sceptics attempt to present scenarios where a widespread inclination toward immorality aligns with one's self-interest. As a consequence, the question “Why be moral?” implies a question about our motivation in the form “Why should I feel motivated to act morally?”, “What is it for me?”. This leads us to enter the topic of what moral motivation is.

Connie Rosati (2016) describes the phenomenon of moral motivation as the question of the alignment (or misalignment) between our behaviour and our moral judgment, understanding that sometimes the former can spring from the latter. This motivation, she explains, is just one instance of a broader phenomenon known as normative motivation, where other normative judgments also tend to carry some motivating force. Judgments about what is good for us, reasons for specific actions, or the rational course of action also typically move us. Many philosophers consider this motivating force as a defining feature that distinguishes normative judgments from other types of judgments, such as mathematical or empirical ones, which lack intrinsic connections to motivation and action. In fact, the “normative” aspect of morality specifically refers to its motivating (and, at times, prescribing) dimension. If I believe that an action x is morally wrong, then it is not just the case that I refrain from doing it. If I believe something is wrong, truly, then there is a “force” and not just an inclination that leads me not to act in that way. There might be compelling reasons, for example, to keep a promise because the sole fact that we made it is a source of motivation to keep it; in other cases, we might be motivated by overriding reasons that make us break that promise. The normative aspect of normative judgments is that they compel us to act. 

Philosophers have developed diverse views on moral motivation, leading to varying perspectives on foundational issues in ethics. These views involve specific theses that impact discussions about moral semantics and the nature of morality. There are two main positions regarding the source of moral motivation. The first one considers that moral motivation derives from the properties found in our moral judgments. The idea is that our motivation aligns with our moral judgments, especially when those judgments are reasonably accurate because moral properties such as rightness and goodness possess an inherent motivational quality that influences us when we recognise them. From this perspective, the fact that we feel motivated to do good actions or stop doing wrong ones derives from our awareness of the properties of the action we are judging. Thus, what moral judgments do is represent natural properties found in external facts. We do actions that we deem as good because there is a property in that action that we recognise as such. This view is generally attributable to Plato’s theory of Ideas (or Forms), as the Idea of the Good is an external, real property of the world that we can grasp. A modern proponent of this view is Christine Korsgaard (1996), who presents the concept of entities with an objective prescriptive nature, although she clarifies that these entities do not qualify as moral properties like Plato’s theory. While her view differs from Plato’s regarding objective values, Korsgaard still believes that there are existing entities that can meet the dual criteria of providing both "a direction and a motive" to the agent who is aware of them. According to Korsgaard, it is a fundamental aspect of human life that entities capable of instructing and compelling us exist, namely, people and other animals (Korsgaard, 1996, p. 166). This notion is at times associated with the views of Immanuel Kant's moral philosophy. The key takeaway for the current discussion is that some philosophers, including Korsgaard and those influenced by ideas from Kant's moral philosophy, maintain an affinity for the notion that moral motivation and normativity originate from inherently normative or "objectively prescriptive" entities. 

Figure 6: Untitled (Beksinski, 1985).

The second important theoretical perspective to understand moral motivation is the one derived from David Hume’s philosophy. Instead of focusing on the existence of natural properties, some philosophers pay attention to the motivating power of moral judgments. By shifting the attention from an external objective property in the world to the nature of our moral judgments, philosophers leave open the idea that the motivating power of morality might be the result of a combination of an inner desire or conative state and some external factor. Hume, in his famous book An Enquiry Concerning the Principles of Morals, presents the idea that moral judgments express a desire. According to this Humean perspective, motivation necessitates more than just belief; it always requires the concurrent presence of a desire or conative state. Therefore, moral motivation cannot solely stem from moral belief acquired by the presence or attribution of a natural property in the world. Motivation must also rely on a preexisting desire or another type of motivating state. Although a widely held view, there are still many philosophers who disagree with this perspective. For them, the precise mechanism by which moral belief can serve as a motivator is a matter of debate. Some assert that moral belief alone is adequate to directly prompt action. For instance, merely believing that keeping a promise is right can compel the believer, to some extent, to act in accordance with that belief. Others argue that moral beliefs give rise to desires, which then collaborate with moral beliefs to induce motivation. In this framework, believing that keeping a promise is right generates a desire to fulfil it, and these cognitive and conative states collectively propel the believer, at least to some degree, to act in a manner aligned with keeping the promise. 

The role of the sceptic in this picture is one of doubting the source of our moral motivations. Either our moral motivation depends exclusively on our own desires to act, and then morality would not constitute a source of motivation, or there is no such thing as a “moral property” in nature. For the moral sceptic, it would be enough that we can disregard the strength of our moral beliefs based solely on mind-independent properties of the world. This would not necessarily mean that the moral phenomenon does not exist, but it would certainly shift the whole of morality to another level of explanation. 

Conclusion

The exploration of scepticism, particularly in its epistemological and practical moral dimensions, unveils a profound questioning of the foundations of knowledge and moral motivation. Tracing the historical roots of scepticism back to ancient philosophers like Pyrrho, Sextus Empiricus, Arcesilaus, and Carneades, the enduring challenge to beliefs, knowledge, and truth underscores the persistent nature of sceptical inquiry. The philosophical landscape grapples with the intricate interplay between belief, knowledge, and truth, inviting scrutiny into the justification of our convictions.

Juan Comesaña's classification introduces two distinct forms of scepticism—Cartesian (or dogmatic) and Pyrrhonian—differing in the intensity of their claims. The former contends that we can only justify the suspension of judgment, while the latter extends this doubt universally, refusing to commit to meta-level beliefs. These nuanced perspectives challenge the very fabric of our epistemological foundations, prompting a reconsideration of our reliability in the chain leading to knowledge.

The subsequent exploration of practical moral scepticism delves into the motivational underpinnings of ethical behaviour. Sinnot-Armstrong's dissection of the question "Why be moral?" unpacks the multifaceted nature of moral motivation, scrutinising whether reasons for morality are inherently self-interested or extend beyond personal gain. Rosati's insights on moral motivation, drawing distinctions between normative judgments and their motivating force, offer a rich tapestry for understanding the driving factors behind ethical actions.

Ultimately, scepticism challenges our fundamental assumptions, forcing us to confront the uncertainties embedded in our beliefs, knowledge, and ethical motivations. As we navigate these philosophical inquiries, the elusive quest for certainty persists.

Bibliographical References

Chisholm, R.M., (1966), Theory of Knowledge, Englewood Cliffs, NJ: Prentice-Hall. Second edition 1977. Third edition 1989.

Comesaña, J. and Klein, P., (2019) Skepticism, The Stanford Encyclopedia of Philosophy, Zalta, E. N. (ed.).

Hume, D., (1975) An Enquiry Concerning the Principles of Morals, Oxford: Clarendon Press.

Korsgaard, C., (1996) The Sources of Normativity, Cambridge: Cambridge University Press.

Machuca, D., (2018) Moral Skepticism: New Essays, New York: Routledge.

Mackie, J. L., (1977) Ethics: Inventing Right and Wrong, New York: Penguin.

Rosati, C., (2016) Moral Motivation, The Stanford Encyclopedia of Philosophy, Zalta, E. N. (ed.).

Steup, M. (1996) An Introduction to Contemporary Epistemology, Upper Saddle River, NJ: Prentice Hall.

Sinnott-Armstrong, W., (2006) Moral Skepticisms, New York: Oxford University Press.

Sinnott-Armstrong, W., (2019) Moral Skepticism, The Stanford Encyclopedia of Philosophy, Zalta, E.N. (ed.)

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