The distinction between “self-interest” and “own interest" in Adam Smith's work is a puzzle for translators. Learn how Alvaro Perpere Viñuales solves it. 
Editor's Note: This post can be found in Spanish translation here.

The question of how the notion of “self-interest” in Adam Smith’s thought, and specifically, in An Inquiry into the Nature and Causes of the Wealth of Nations (hereinafter WN) should be understood has and continues to spark works and discussions[1]. It is generally recognized how important this is in the Scotsman´s framework, although there are differences about how it should be understood. For example, in the “General Introduction” of WN edited by R. H. Campbell and A. S. Skinner (The Glasgow Edition) the following is stated, “In all these cases social benefit and economic order are the result of self-interested actions of individuals rather than the consequences of some formal plan”[2] (my emphasis).

Much has been said about the notion of “self-interest” in Smith’s works, accepting that, I will nevertheless make a new approach to the topic. My native language is not English and I have translated Adam Smith’s works into Spanish. Leaving aside the conceptual analysis, I will show readers, especially English-speaking readers, elements that perplex foreigners who read his works, but in particular those who read WN and try to translate it. From a translator´s perspective, from the perspective of someone who looks carefully at each single word, there is no defense or praise of “self-interest” as a driver of human action in WN. In my opinion, this is one of the biggest challenges (but not the only one) that a translator faces, and probably the cause of many misunderstandings among Spanish readers. I will try to show this by highlighting three elements.

The first element can be called “nonexistence of expression.” The first thing that catches a translator’s attention is that in WN, surprisingly, the expression “self-interest” is seldom used. What is more, where one might expect to read “self-interest” Smith always writes “own interest.” For example, in the famous passage where he says “It is not from the benevolence of the butcher, the brewer, or the baker, that we expect our dinner, but from their regard of their own interest” (WN I, ii, pp. 226) Smith's specifically says “own interest” and not “self interest.” A little further on, bankers act following their “own interest” and not their “self-interest” (WN II, ii, 64, pp. 307) When referring to money lending, Smith uses the same expression to explain both the behavior of the one who lends and that of the one who receives the money; they do so motivated by their “own interest” [3]. The famous reference to the “invisible hand” also appears linked to the concept of “own interest” and not to “self-interest” [4]. In short, whenever Smith wants to praise personal interest as a central element of human action, the expression he uses is “own interest” and not “self-interest.”

For those whose native language is not English, this difference between “own” and “self” preceding “interest” is particularly intriguing. At the same time, it introduces a difficulty that is almost impossible to solve when translating it into Spanish. The Spanish translation for the expression “own interest” and for the expression “self-interest” is the same, “interés propio” or “interés personal”. But when we look at English dictionaries (something that non-natives are obliged to do in these cases), we find that “own” and “self ” do not refer exactly and identically to the same idea. Although both words refer to the subject which makes the decision, the word “self” refers to the interest of the “subject” in a stronger and more exclusive way than the word “own”. Or, from another perspective, the word “own” refers to the subject himself, but without denying the possibility of other people obtaining some benefit. As everyone can see in Smith´s examples, the baker's “own interest” benefits him, but this is closely related to the customers’ benefits, just as the brewer's “own interest” is closely related to the benefits that their customers have when they drink their beer. The baker’s and the brewer’s interests, although focused primarily on their benefit, also have a positive effect on others. In fact, it is because of this that they can trade. For this reason, in WN the concept of “own interest” is also related with concepts like “persuasion”, in which one and the other establish a relationship trying to show to the other person the advantages of the relationship and the gains that he or she will obtain. It is not a violent imposition, it is an agreed relationship.

The second element I would like to highlight complements the previous one. In WN, Smith always praises “own interest” and points out the benefits that are obtained from acting motivated by it. Interestingly, in those passages where he chooses to use the expression “self-interest” instead of using “own interest”, he describes actions that are not really beneficial for the entire society but only and exclusively for those who act motivated by it. Specifically, “self-interest” appears when he describes the motivation of the Mendicant friars. There, Smith points out that mendicants are guided by “self-interest” (not by “own interest”). Their actions, guided by their “self-interest”, are linked to the principle that states “no plunder, no pay”. Because of this, they are forced to use “any method” to obtain the devotion of the common people, and, along with it, their livelihood (WN V, i, g, 2, pp. 789). Unlike “own interest”, the notion of “self-interest”, when it appears, is associated with the ideas of “looting” and “violence” rather than with those of persuasion and negotiation[5].

The third and last thing that draws the translator's attention arises when reviewing other works by Smith. Smith paid special attention to the use of words and to the use of language in general. The expression “self-interest” does appear in Smith’s The Theory of Moral Sentiments, but in my opinion an extract from the Lectures on Jurisprudence is tremendously puzzling. If we look at the Glasgow edition, in the 1766 report we read:
There is no natural reason why an Englishman or a Scotsman should not be as punctual in performing agreements as a Dutchman. It is far more reduceable to self interest, that general principle which regulates the actions of every man, and which leads men to act in a certain manner from views of advantage, and is as deeply implanted in an Englishman as a Dutchman (p. 538).
The similarity (and difference) with WN is immediately noticeable. It is very clear that from one work to the other there is a change from “self-interest” to “own interest” as a fundamental principle of human action. Is this coincidental or does it reflect Smith’s decision to choose a more precise expression?

In short, from a translator’s perspective, WN’s idea of “self-interest” is paradoxical. First, because the expression that Smith’s uses throughout the entire WN is “own interest”. Second, because in those few cases when “self-interest” appears, it is not to describe a positive or beneficial action for society but only for one person. And third, because Smith is so exquisite and precise with his language, it is difficult to think that his use of “own interest” instead of “self-interest” was casual or accidental.

For someone whose mother tongue is English, the distinction between “self-interest” and “own interest” may seem accidental, but for those who devote themselves to translating Adam Smith’s works, this is a puzzle. And, in my opinion, these kinds of problems add more trouble to understanding Smith’s ideas and the true sense of some of his key concepts in other cultural contexts. [5] 

Footnotes
[1] An interesting essay on this topic, written by Lauren Hall, can be read at  https://www.adamsmithworks.org/documents/self-interest-rightly-understood

[2] General Introduction to WN, p. 34

[3] “To borrow or to lend for such a purpose, therefore, is in all cases, where gross usury is out of the question, contrary to the interest of both parties; and though it no doubt happens sometimes that people do both the one and the other; yet, from the regard that all men have for their own interest, we may be assured, that it cannot happen so very frequently as we are apt to imagine.” (WN, III, iv, 2) (p. 350) (my emphasis).

[4] “By preferring the support of domestick to that of foreign industry, he intends only his own security; and by directing in such a manner as its produce may be of the greatest value, he intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention.  Nor is it always the worse for the society that it was no part of it. By pursuing his own interest he frequently promotes that of the society more effectually than he really intends to promote it” (WN IV, ii, 10) (p. 456)

[5] About the ideas of “persuasión” and its opposites, see L. Montes en”Adam Smith’s foundational idea of sympathetic persuasión”, en Cambridge Journal of Economics, 43, 1, 2019.