Although scholars have found significant echoes of Aristotelian principles in Ayn Rand's ethics, Rand herself was somewhat dismissive of Aristotle's approach to moral issues ("The Objectivist Ethics", 14):
No philosopher has given a rational, objectively demonstrable, scientific answer to the question of why man needs a code of values. So long as that question remained unanswered, no rational, scientific, objective code of ethics could be discovered or defined. The greatest of all philosophers, Aristotle, did not regard ethics as an exact science; he based his ethical system on observations of what the noble and wise men of his time chose to do, leaving unanswered the questions of: why they chose to do it and why he evaluated them as noble and wise.
These sentences reveal such a fundamental lack of familiarity with the sophisticated arguments presented in Aristotle's Nicomachean Ethics that I wonder if Rand ever did more than glance over the copy of the complete works of Aristotle that she bought in the 1940s. The image conjured up here is that of Aristotle as philosophical pollster, clipboard and pen in hand, dilligently surveying the conventionally noble and wise men in Athens to construct a composite picture of their unquestioned ethical assumptions. That picture is very far from the truth.
It is true that Aristotle does not think that ethics is an exact science, but at the same time it is not clear if Rand's understanding of the concept "exact science" is the same as Aristotle's. In modern usage, a science is considered to be exact if it admits of precise measurements, well-defined causation, and testable hypotheses and theories. Thus hard sciences such as physics and chemistry are commonly thought to be exact, "softer" sciences such as psychology are thought to be inexact or only partially exact, some of the life sciences (e.g., biology), historical sciences (e.g., geology), and social sciences (e.g., economics) are thought to hold a mediate position, and other fields of knowledge (e.g., history, aesthetics, ethics) are even now considered to not be sciences at all, or at best to be proto-sciences. The reasons are fairly clear: the phenomena of (say) physics and chemistry are relatively simple and well-understood despite their manifest complexities, whereas the phenomena of (say) history and sociology are so complex and poorly-understood that scholars find it difficult to define the dimensions along which measurements could be made, to determine the range of plausible causes for the phenomena under study, and to formulate hypotheses and theories that are even potentially testable.
Aristotle appears to have recognized some of these difficulties in a well-known passage from the Nicomachean Ethics, where he sets out some of his reasons for thinking that ethics is not an exact science (1094b11-1094b27, translated by Terence Irwin):
Our discussion will be adequate if its degree of clarity fits the subject-matter: for we should not seek the same degree of exactness in all sorts of arguments alike, any more than in the products of different crafts.
Moreover, what is fine and what is just, the topics of inquiry in political science, differ and vary so much that they seem to rest on convention only, not on nature. Goods, however, also vary in the same sort of way, since they cause harm to many people; for it has happened that some people have been destroyed because of their wealth, others because of their bravery.
Since these, then, are the sorts of things we argue from and about, it will be satisfactory if we can indicate the truth roughly and in outline; since [that is to say] we argue from and about what holds good usually [but not universally], it will be satisfactory if we can draw conclusions of the same sort.
Each of our claims, then, ought to be accepted in the same way [as claiming to hold good usually], since the educated person seeks exactness in each area to the extent that the nature of the subject allows; for apparently it is just as mistaken to demand demonstrations from a rhetorician as to accept [merely] persuasive arguments from a mathematician.
Later, when summarizing the outline he has provided in Book 1 of the Nicomachean Ethics, Aristotle provides some further insights into his notion of exactness (1098a24-33, translated by Terence Irwin):
This, then, is a sketch of the good; for, presumably, the outline must come first, to be filled in later. If the sketch is good, then anyone, it seems, can advance and articulate it, and in such cases time is a good discoverer or [at least] a good co-worker. That is also how the crafts have improved, since anyone can add what is lacking [in the outline].
However, we must also remember our previous remarks, so that we do not look for the same degree of exactness in all areas, but the degree that fits the subject-matter in each area and is proper to the investigation. For the carpenter's and the geometer's inquiries about the right angle are different also; the carpenter's is confined to the right angle's usefulness for his work, whereas the geometer's concerns what, or what sort of thing, the right angle is, since he studies the truth. We must do the same in other areas, too, [seeking the proper degree of exactness,] so that digressions do not overwhelm our main task.
Still later, Aristotle contrasts the level of exactness needed for right action with the level needed for scientific study (1103b34-1104a11, translated by Terence Irwin):
But let us take it as agreed in advance that every account of the actions we must do has to be stated in outline, not exactly. As we also said at the start, the type of accounts we demand should reflect the subject-matter; and questions about actions and expediency, like questions about health, have no fixed [and invariable answers].
And when our general account is so inexact, the account of particular cases is all the more inexact. For these fall under no craft or profession, and the agents themselves must consider in each case what the opportune action is, as doctors and navigators do.
The account we offer, then, in our present inquiry is of this inexact sort; still, we must try to offer help.
For Aristotle, then, a science is exact when its principles apply without qualification or modification to all particular cases (i.e., they are not just usually but universally true), or at least when the exceptions to its general principles can be stated in a clear and detailed manner. However, when a field of study is focused on usefulness rather than scientific completeness, what matters is that its conclusions conduce to right action; and the point of ethics is not to define an exact science but to help one live a good life.
By contrast, Rand does seem to have believed that ethics is or could be an exact science; yet her conception of ethics as an exact science was more of promissory note than an achieved reality. Her essays on ethics make for stimulating reading, but when it comes to human choices and actions her principles do not propose testable hypotheses for the choices people might make or the actions they might take, set out a fully explanatory set of causes for human behavior, or define dimensions along which choices or actions can be precisely measured for goodness or value.
For instance, in her Introduction to Objectivist Epistemology (IOE) she claimed that an ethical concept like love can indeed be measured, but that the measurements in question are ordinal (e.g., this is the second most intense love I have ever experienced) rather than cardinal (e.g., this love is worth investing 1,000 hours of my time). Rand ties this claim to her definition of a moral code as "a system of teleological measurements which grades the choices and actions open to man, according to the degree to which they achieve or frustrate the code's standard of value" (IOE, 33). Yet are these teleological measurements scientifically exact? Is Rand claiming that the objective value of an individual's choices can be precisely and accurately measured by an appropriately scientific ethicist?
Consider an analogy that Rand pursues at some length: just as money provides a medium of exchange in the economic realm, which is used as a measure of material value, so also "the same kind of measurement guides man's actions in the wider realm of moral or spiritual values.... But the currency or medium of exchange is different. In the spiritual realm, the currency -- which exists in limited quantities and must be teleologically measured in the pursuit of any value -- is time, i.e., one's life." (IOE, 33-34) Presumably Rand would argue that economics is an exact science because it possesses a dimension along which values can be measured (i.e., prices). Yet prices are a social phenomenon. True, the price that any individual will pay for a given item can be roughly measured in any given transaction (i.e., by the fact that an individual makes or does not make the purchase at a given price), but this value is personal or (in the language of the Austrian school of economics) subjective rather than objective. The objective nature of economic value emerges in a social context through the myriad individual interactions among buyers and sellers. And, most importantly for our discussion here, the scientific nature of economics arises not at the personal or subjective level, but at the social or objective level. The particular decisions of a particular economic actor are a matter for psychology, not economics.
Furthermore, time (the spiritual currency that Rand posits) is inherently personal or subjective. There is no objective measure of the "content" and "intensity" (IOE, 31) of a given activity, no way to sum that content and intensity over all individuals to arrive at an objective measure of the value of that activity. And even if there were, such a measure would be inherently social (as is the market price of a given economic item), and thus diametrically opposed to Rand's ethical individualism.
Finally, as Aristotle notes "the account of particular cases is all the more inexact, for these fall under no craft or profession". For example, it has taken decades and centuries of cumulative knowledge-gathering and knowledge-application by hundreds of thousands of doctors to bootstrap the craft of medicine into a science, because science is not just a particular result but a process of inquiry and a community of inquirers; and even though medicine has built up such an extensive institutional infrastructure, there remains as much art as science in the field. In the field of ethics, there is no such institutional infrastructure, no such cumulative body of objective knowledge, no such community of scientists using agreed-upon methods of inquiry.
No, ethics is not an exact science, and Rand did not prove that it is (or even illuminate the general direction in which such a proof could be pursued). Perhaps one could argue that ethics is a normative science and therefore not subject to the same stringent requirements as experimental sciences like physics or explanatory sciences like geology; but Rand does not make this argument or do the work necessary to justify it -- and in any case such an argument would give the lie to Rand's claim that ethics is an exact science. In the end, Rand's ethics is just as inexact as Aristotle's, except that she did not have the intellectual honesty to admit it.
(To be continued...)