As a result of this, justice must be determined for the exchange to occur properly. Aristotle sees that particular justice applies, for it deals with quantitative relationships. Even more important is reciprocal justice, for, " ... in associations for exchange this sort of justice does hold men together – reciprocity in accordance with a proportion and not on the basis of precisely equal return." (Ethics, 1132b, 32-4)(10). With reciprocal justice looking at particular mutual benefits for both sides, it would seem that Aristotle has also founded the early beginnings of the Law of Comparative Advantage. It is vital to understand that during any market exchange, both sides hope to benefit. If no benefit is derived, or either side feels that their expectations are not being fulfilled, then the exchange will unjustly take place, or even not at all. There must be a ratio of exchange values to be equalized for both sides to carry out the transaction.

          Some, including this writer, are quite confused as to why Aristotle tried to make sure that the goods in an exchange must always be equalized. This is quite hard to determine, and it would seem that one would have to be able to derive intrinsic benefits from a good to make such calculations, although even this would not make the task any easier Even though his idea of making sure that exchange levels must always be equalized for both parties seems quite absurd, he correctly understood that exchanges only take place because each side looks to gain a good to better their objective ends.

          With Aristotle's views established, now it is time to look for comparisons and contrasts with Carl Menger's theory of value. Menger's fame came when he gave further substance to Aristotle's early inklings on marginal utility. In conjunction with W. Stanley Jevons and Leon Walras, they established the Theory of Diminishing Marginal Utility as a set economic theorem for analysis. While his colleagues used the theory in a more "numerical" and "mathematical" manner by trying to find derivatives of an overarching Marginal Utility "Equation," Menger saw it as a philosophical principle that could be applied in everyday language and to everyday life. He adamantly opposed the "objective" theory of value espoused by Adam Smith and Karl Marx, for he thought that value was not integrally determined by the labor factors necessary to produce a "good." He summarizes his view in his great treatise when he says:

          For Menger, value can only be given "to things" by rational human beings. Like Aristotle, this might appear, on the surface, as a subjective theory of value, but Menger pushes for an "objective" stance, in that value is given to a good if the good helps to further or fulfill a need of an economizing individual. This starting point is virtually synonymous with Aristotle. Menger, like Aristotle, saw the importance of scarcity in the equation, when he said:

          With these similarities to Aristotle, Menger will continue to build upon the ancient philosopher's "objective" theory of value.

          Menger does see a problem with differences in value over time, and he explains this by using a very Aristotelian perspective. For him, casual connections are very vital to understanding how values change with time. By tracing these connections and finding the "causes," an economizing individual is better able to make proper value judgements. This process is a twofold endeavor, for: "We must investigate: (1) to what extent different satisfactions have different degrees of importance to us (subjective factor), and (2)which satisfactions of concrete needs depend ... on our command of a particular good (objective factor)." (Principles of Economics [1994], 3.ii.2)(13).

          Menger did seem to espouse a "contextually-relational objectivism," where value depends on the subject, the object, and the situation itself(14). Value has to have all three to even attempt to make proper judgements. By only focusing on one of the three aspects, it is no wonder that many had derived quite ludicrous theories of value in the time since Aristotle's death. Menger was keenly aware that people look about the world, develop concepts, and then they personally rank certain "valuable" goods. For the most part, people, " ... will usually prefer satisfactions on which a higher degree of their well-being depends." (Principles of Economics [1994], 3.ii.a.1)(15). This point emphasizes Menger's interest in a bio-centric theory of value, where people assign values to those things that will most benefit their survival. Unlike instinct among animals, humans possess reason that helps them "rank order" the values of potential goods.

          In addition to the bio-centric point, Menger at this juncture gives his best summary of what would become the Law of Diminishing Marginal Utility. In order to explain this aspect of the value theory, Menger will illustrate that:

          Consumption extending beyond even this point has merely the importance of a progressively weaker pleasure, until it finally reaches a certain limit at which satisfaction of the need for food is so complete that every further intake of food contributes neither to the maintenance of life nor to the preservation of health – nor does it even give pleasure to the consumer. (Principles of Economics, [1994], 3.ii.a.5)(16).

          By giving this example, Menger provides a more precise account of marginal utility, and he even gives it a numerical content by including a graphic chart of diminishing marginal utility in his book. Menger saw that one had to use his or her subjective consciousness to weigh the different relative values of each good, but the economizing individual would then use his or her considerations to make a decision as to what goods to pursue to help satisfy their needs to the fullest possible extent. This may appear a bit too utilitarian (just like Aristotle's early musings on marginal utility), but unlike John Stuart Mill's ideas, Menger's notion of utility is primarily an individualistic perspective held by each person.

          Now that the subjective factors and the context of the situation have been addressed, Menger then delves into the objective factors. Although determining value seems quite easy if the situation involves just one good, Menger saw that, " ...in ordinary life the relationship between available goods and our needs is generally much more complicated. Usually not a single good but a quantity of goods stands opposite not a single concrete need but a complex of such needs." (Principles of Economics, [1994], 3.ii.b.2)(17).

          Even though things may become quite complex, goods still need to be employed to fulfill the highest needs that an individual possesses. Aristotle also was aware of this problem, but he confused the situation with his unusual handling of "exchange values," in regard to making goods commensurable. Even though goods for exchange may be "unequal," for Menger their measure is determined by the degree of importance that they have to the welfare of the participants. As a further clarification of Aristotle's confusion, Menger sees that questions of equality in exchange are solved by "differences of quality." For the economizing individual, "Human needs may be satisfied either in a quantitatively or in a qualitatively different manner by means of equal quantities of qualitatively different goods." (Principles of Economics, [1994], 3.ii.c.6)(18).

          Menger attempted to solve the disparities and troubles of Aristotle's exchange theory by emphasizing that certain goods for exchange can be weighed differently by the level of "quality" present at the time of exchange. For example, quantitatively, for exchange purposes, a ton of coal is worth about three tons of timber, while, qualitatively, clothes from a "trendy" store are worth more than those from a discount store. In essence, this was the dilemma that plagued Aristotle, but Menger was able to show that over time things don't become equal exactly, but in a proportional manner.

          As part of his attempt at improving Aristotle's view on exchange, Menger's theory of price is one of "price formation." In a search for the causal connections in the exchange market, Menger saw that prices were formed by the market participants, not intrinsically in the goods themselves. The price of goods are a part of the process of individual want satisfaction. During the process of determining the price, each participant will state the price that he or she is willing to pay, and then through a "bargaining process" the individuals agree on a price of exchange that corresponds to each person's necessary want satisfactions. Menger was quite aware that, " ... it is easy to commit the error of regarding the magnitude of price as the essential feature of an exchange." (Principles of Economics, [1994], 192)(19), for this would lead to thinking that the goods exchanged must be "equal" (Aristotle's problem) or that the prices in an exchange are determined by the labor costs in producing the goods (Marx's problem).

          The last part of Menger's value theory that will be examined is in regard to the value of goods of "higher order." He held that, " ... the value of goods of higher order is dependent upon the expected value of the goods of lower order they serve to produce." (Principles of Economics, [1994], 3.iii.a.3)(20). Goods of higher order, capital goods, only have value, if, " ... they serve to produce goods that we expect to have value for us." (Principles of Economics, [1994], 3.iii.a.3)(21).

          With this in hand, these higher order goods only attain value by the "prospective value" of the goods of lower order. All of these higher order goods help contribute to the production process that yields "consumer goods," which are valued by individuals depending on their varying levels of want satisfaction. Finding the total present value of goods of higher order required for the production of a good of lower or first order is equivalent to the "prospective value" of the product to economizing individuals.

          Through the production process, goods of higher order are weighed by their perceived value to people when they are used to produce certain commercial goods, and this results in a better allocation of resources in the economy. In addition to this talk of goods of higher order, Menger hopes to disprove theories of value that only look at the labor, only the capital, or only the land involved in the production of consumer goods.

          In conclusion, a comparison of the economic thoughts of both Aristotle and Carl Menger give keen insights into the perceived notions of value that many individuals hold today. Although many people may not consciously realize that they are following the views held by these men when they are in the supermarket trying to choose between the regular and low-fat yogurt, these theories of value are reflective of man's nature and life in the world. By expressing how people can determine values based on what is needed for the betterment of their lives, without the coercion of an outside influence (i.e., the government), Aristotle and Menger both influenced the development of free market ideas.

          Menger does appear as an Aristotelian at heart, even though he corrected Aristotle's confused understanding of commensurability. For the most part, the two are virtually synonymous except for Menger's more modernistic interpretations and ideas on "higher order goods." If a person ever wonders why they like one product over another, he or she only has to examine the works of an ancient Greek philosopher and a 19th Century economist.