The capitalist market economy claims that it is a strictly performance-oriented society. For the wage-dependent worker this should mean that whoever performs on a high level in terms of quantity and quality receives a relatively high share of the total societal product through the payment of a relatively high wage for individual use. For the entrepreneur who generates income through the utilization of the capital this means that a manager who excels in competition due to highly skilled business activity generates a high profit. In addition to this "positive" performance principle, there is also the "negative" performance principle. For the workers that means that especially the "underperforming" workers are always threatened by the loss of their job. For entrepreneurs that means that the "weaker performers" are also threatened by bankruptcy. Both creates a considerable pressure to perform on each individual, so that within the capitalist market economy this performance principle is seen as a sufficient stimulation of individuals and is thus used as an almost exclusive principle of motivating individuals.
For whatever reasons there are huge differences in income in the capitalist market economy, which, because of their apparent spontaneity, are often to be accepted as an inherent characteristic of the (capitalist) market economy. Nevertheless, the question remains whether this capitalist performance principle contributes to the creation of optimal economic structures in the interests of society as a whole and thus to create economically and politically stable conditions in society
The socialist planned economy also claimed to offer reward according to the performance principle. However, it deliberately refrained from applying the "negative" performance principle. As a substitute for this, attempts were made to use more idealistic performance stimulation in the form of "socialist competition", which essentially failed. The wage structure did not develop in a spontaneous process of supply and demand. It was also not negotiated in a combative dispute between the organized representatives of two classes, but rather determined administratively. Since the principle of the greatest possible social equality was sought for ideological reasons the wage differences under socialism were relatively small.
In discussions about the performance principle it is usually fairly easy to reach a consensus that the income differentiation in socialism was too small to produce an effective performance principle. And in capitalism it is too big to achieve a sustainable, socially acceptable capitalism. I have not yet heard any plausible considerations for where there should be an objectively justifiable, fair differentiation in between
A premise for answering this question is the clarification of the concept of "performance" for human work within the societal reproduction process. The use of the terms "performance" and "work" in physics serve as inspiration. In physics a scalar value can be specified for the amount of work performed in a unit of time, regardless of the physical form in which it is performed. Since all forms of energy can actually be converted into one another, there are reproducible conversion factors for various performances, regardless of whether these are mechanical, electrical or thermal performances, for example.
For human labor, too, there are some professions where it seems to be possible and to make sense to quantify the work. These are manual activities that are constantly repeated in the same form with negligible differences in quality. Here the performance can be viewed as proportional to the number of items produced (piece wage). But that is about it. Already trying to compare different manual tasks with one another is difficult. For example, how do you compare the performance of cutting hair with the performance of milking a cow? Even within a single professional group it is often difficult to evaluate individual performance. For example, who can objectively evaluate the differences in performance between two teachers
This results in the question whether it makes sense at all to introduce the concept of "performance" for human work, which suggests that this performance is also measurable. Unfortunately, despite the difficulties, there is no way to simply avoid the problem. It is necessary to install a distribution system of goods in a societal system in which people work together and consume individually, because the individual must be motivated to participate in the joint work, which requires effort to use its abilities as best as possible. It is of course tempting to activate the quantitatively and qualitatively different abilities of the members of society through a differentiated distribution of goods, which was only possible through the regular production of a surplus product.
Marx assumes the measurability of human labor by regarding the necessary working time as the measure of the work done. He writes: "But how does one measure quantities of labour? By the time the labour lasts, in measuring the labour by the hour, the day, etc" In doing so, he takes into account that there are individual differences in the quantity and quality of the various professions as he continues writing: "Of course to apply this measure, all sorts of labour are reduced to average or simple labour as their unit."  Elsewhere he also comments on this "Andrerseits muß in jedem Wertbildungsprozeß die höhere Arbeit stets auf gesellschaftliche Durchschnittsarbeit reduziert werden, z.B. ein Tag höherer Arbeit auf x Tage einfacher Arbeit. Man erspart also eine überflüssige Operation und vereinfacht die Analyse durch die Annahme, daß der vom Kapital verwandte Arbeiter einfache gesellschaftliche Durchschnittsarbeit verrichtet."(On the other hand in each averaging process, the higher work always has to be reduced to average work, e.g. one day of higher work to x days of simple work. This saves a superfluous operation and simplifies the analysis by assuming that the worker employed by capital does simple average societal work  He does not go into any further detail, so that the problem of evaluating individual work could of course not be adequately clarified by him. At that time other problems had priority, which is the formulation of the law of value.
The protagonists of the capitalist market economy leave this problem, like so many others, to their universal control mechanism "supply and demand". They save themselves intensive thinking about it according to the motto "The market will fix it".
In my market economy models  I also initially avoided the problem by idealizing the workers into an economic subject with a uniform, universally applicable labor. In doing so, I tacitly assumed that every worker who finds work uses its labor with normal intensity, without worrying about what motivates the individual.
Since the functioning of a market economy cannot be made plausible without the formulation of the facts that motivate the individual to act I will now focus on this problem in more detail. I will not base it on a mechanistic concept of performance but approach the problem from a different angle to obtain a more nuanced view of the problem and facilitate objectively quantifiable statements.Return Go on