Three Schools of Thought
This piece is intended as an instructional text for an introduction to effective altruism at UC Berkeley. It may be used in other contexts as an introduction to the major schools of ethics, but it should be understood as a heuristic and non-comprehensive foray towards understanding those schools; nothing more. Additionally, this introduction fails to introduce the reader to important schools of thought in non-Western and religious traditions.
Names of the Three Schools:
The three major schools of ethical thought in the Western tradition are virtue ethics, deontological ethics, and consequentialist ethics. They received their names for important historical reasons, but for our current introductory purposes, these names can be confusing, so I will replace some of them with commonly used synonyms: character (or character-based) ethics for virtue ethics, and action (or duty-based) ethics for deontological ethics.
The Differences between the Three Schools:
To clarify the differences between the three schools, it is worth considering an example, and how the different schools interpret the case. Consider the situation where “Cain killed Abel”. For the sake of our example, let’s assume that this sentence, “Cain killed Abel”, represents an immoral fact of the world that has occurred. Note this sentence has three grammatical parts, a subject, a verb, and a predicate. Roughly speaking, character-based ethics asserts that the moral substance inhabits the subject, Cain; duty-based ethics contends that morality stems from the verb, killed; while consequences-based ethics emphasizes that the moral content of the sentence resides with the predicate, Abel.
Specifically, for a character-based ethicist, there is a moral defect in Cain. For a duty-based ethicist, there is a moral prohibition against the act of killing, so the moral wrong arises from the action of killing. For a consequences-based ethicist, the moral wrong arises from the consequences, namely the suffering endured by the predicate, Abel.
Heuristic Historic Explanations of the Schools of Thought
This is probably the most prevalent of the three in Western history, but also the least popular currently. The most famous proponent of character-based ethics is Aristotle. Arguably, character-based ethics makes the most sense within an organic and hierarchical worldview, where language to frame predicting the future is virtually non-existent. (We must keep in mind, statistics and probability theory are relatively recent phenomena in human history.) Under hierarchical worldviews, a typical contention is that for society to sustain itself, different people must play different roles, and if people fail to play their roles properly, then society will fail to sustain itself. An analogy that helps explain this view is the human body. The organs of the human body have different roles and functions they need to fulfill to sustain the human body. However, if the organs fail to do their duties (e.g., the lungs start pumping blood, and the heart starts storing air), then the body fails to sustain itself. Similarly, under this hierarchical worldview, if scientists fail to build knowledge (because they are fighting in battles badly) or soldiers fail to defend the homeland (because they are working in labs and libraries), then this society is failing because the scientists and soldiers ae having failures in character, because they are failing to fulfill their respective roles. Society will presumably thrive and each person will be in the moral right, if each person fulfills their respective roles correctly.
During the Renaissance, Reformation, and Enlightenment, there was a shift in European societies away from highly hierarchical feudal societies to more, relatively speaking, egalitarian social structures. But this was also a time before we had a good language framework to discuss predicting the future (e.g., statistics). Under such circumstances, a relatively speaking natural way to frame ethics is duty based. What duty-based ethics roughly asserts is that when anyone is confronted with a particular situation, that person is obligated to take certain actions or refrain from particular actions. Probably the most famous proponent of duty-based ethics is Immanuel Kant. In his work, he tried to develop duty-based ethics that applied not only to all humans, but any possible rational being.
The development of consequentialist ethics and of statistics are highly parallel. Prior to the development of statistics, it was difficult for people to express odds for future events, which made discussion of the relations between consequences and ethics more difficult. The earliest versions of Bayes’ theorem and the central limit theorem only arrived in the 18th century; standard deviation and correlation were developed as concepts during the late 19th century; the modern version of the central limit theorem, student’s t-distribution, and the logical foundations of statistics were only established in the early 20th century. The development of utilitarianism, the currently most popular form of consequentialism, is interestingly parallel with the development of statistics. Jeremy Bentham and JS Mill develop the early forms of utilitarianism in the late 18th and early 19th century. John Harsanyi, Oscar Morgenstern, John Nash, and John von Neumann developed the modern foundations of expected utility theory and modern utilitarianism in the mid-20th century. Harsanyi’s version of utilitarianism is probably the most famous formalized version today. With access to large data sets, large data processing capacities, and statistical tools and language, it is much easier to discuss and assess the possible consequences of actions, thus utilitarianism has arguably become the most popular form of ethics in the modern world.
Utilitarianism, in one form or another, is very popular today, especially among effective altruists. But it is worth remembering that it, like all human knowledge, is just a model of a more complex world. Additionally, character-based and duty-based ethics are still widely used today by many people. Understanding these models improves our abilities to understand the motivations and actions of others. Rather than simply adopting one as the true model of the world, it is perhaps more helpful to be familiar with each of these models, understanding that like all tools, they are useful in some situations, but not useful in others.