Many individuals, both religious and secular, have decried what has been described as the crass materialism of the modern age. This criticism of the modern west is not restricted to socialists and leftists. In 1978, famous Russian author and emigre Alexander Solzhenitsyn, certainly no friend to communism, gave a commencement speech at Harvard in which he decried the materialist and legalistic culture of the west as oppressive of human dignity. The earned Solzhenitsyn the ire of the American right, who had hoped his speech would trumpet the glories of American capitalism against the evils of Soviet Communism. Instead, Solzhenitsyn warned that in the capitalist west "destructive and irresponsible freedom has been granted boundless space." Many others before and after Solzhenitsyn have made similar observations.
In his 1981 encyclical Laborem Exercens, John Paul II takes up these questions and lays out a theory which explains the rampant and dangerous materialism of the west in terms of an inversion of values of the twofold meaning of human work. The document is heavily influenced by the philosophy of Personalism that John Paul II favored. Even so, he reaffirms the earlier teaching of the pre-Conciliar popes and even makes significant developments to it.
After a locating on man's vocation to work as found in God's command to "fill the earth and subdue it" (Gen. 1:28), the pope begins a reflection on the nature of work itself. This is of fundamental importance, because most disputes about the economy and economic theory eventually devolve into discussions about the nature of work and the rights of workers. John Paul is breaking new ground here; though previous popes had certainly taught on the rights of workers, John Paul II is the first pontiff to really elaborate on the nature of work. In doing so, he will still arrive at the same conclusions and teachings as Leo XIII and Pius XI, but will do so from a different route. While the former popes stress the rights of the worker based on arguments from justice, John Paul will do the same using the nature of work and man as the subject of work as his theological locus. The result is a beautiful teaching that compliments and deepens earlier Magisterial pronouncements.
His teaching on the nature of work begins with a consideration of work under two different aspects, which we might term the essential and accidental aspects, or as John Paul II prefers to say, its objective and subjective meanings. The objective sense or objective meaning of work is what form the work takes in the world. This may vary from epoch to epoch, but broadly speaking, it is characterized by the manner in which man begins to cultivate the earth, and "transforms its products, adapting them to his own use" even when "the toil of human hands and muscles is aided by more highly perfected machines" . The object of work is thus characterized by the incremental developments of industry and technology over the years, "successive phases of development through new technologies" . The products, technologies and marvels man works with his hands are the object of human work. This will look different as history progresses.
Despite the changes in technology, however, the subject of work continues to be man. Man is the acting agent who is the efficient cause of all labor. Man as the subject of work flows from his personhood, as only persons are capable of work.  Because work is a personal act, it is ultimately ordered to the good of persons, those who benefit from the work, but especially the agent of the work itself. Like other personal acts (the conjugal act and the act of faith come to mind), the act of work, properly understood, makes man more of a man. "As a person he works, he performs various actions belonging to the work process; independently of their objective content, these actions must all serve to realize his humanity, to fulfill the calling to be a person that is his by reason of his very humanity" .
How do the objective and subjective aspects of work interact? From which does work ultimately derive its value? Before delving into this question, John Paul II notes that, because work is a personal act, it is also an ethical act, and we can speak of work having an "ethical value of its own, which clearly and directly remains linked to the fact that the one who carries it out is a person, a conscious and free subject, that is to say, a subject that decides about himself" .
Because work is personal and therefore ethical, there remains the possibility of having a right relationship between the objective and subjective senses, as well as an incorrect, and hence unethical, relation. What sort of unethical relation does the Pope have in mind? John Paul explains the ethical implications:
"This leads immediately to a very important conclusion of an ethical nature: however true it may be that man is destined for work and called to it, in the first place work is "for man" and not man "for work". Through this conclusion one rightly comes to recognize the pre-eminence of the subjective meaning of work over the objective one." 
When the objective value of work is prioritized over the subjective, the result is a situation in which man exists for work, not vice versa; in other words, by valuing the goods and services provided by man over and above man who works and for whom these goods are produced, an offense against human dignity arises by treating man as a means to an end that is purely material.
This question becomes very relevant when we get to the question of just compensation for work. When an employer offers a wage, that wage is based on some criteria. What, for example, determines that a police officer gets paid $50,000 per year while a line cook may only make $19,000? One could respond by saying that these are the prevalent wage levels in the market place. Essentially, a wage is offered in return for the specific skills a prospective worker has. A worker can do X or build X, and X is worth so much to an employer; but another worker can do X,Y and Z, and this is worth much more. This is typically how wages are determined in the workplace, where higher skills and education lead to higher incomes.
Yet John Paul II asks us to reflect on this question of value from another angle. Though he certainly does not deny that different skills can be more or less in demand, he infers from his above reflections on objective and subjective meanings of work that "the primary basis of the value of work is man himself, who is its subject...Given this way of understanding things, and presupposing that different sorts of work that people do can have greater or lesser objective value, let us try nevertheless to show that each sort is judged above all by the measure of the dignity of the subject of work, that is to say the person, the individual who carries it out. On the other hand: independently of the work that every man does, and presupposing that this work constitutes a purpose-at times a very demanding one-of his activity, this purpose does not possess a definitive meaning in itself. In fact, in the final analysis it is always man who is the purpose of the work" .
Thus, when looking at renumeration for work performed, employers ought to always bear in mind that the value of any human work flows from the dignity of the one who performs it. It is related to the specific skill or product produced objectively - related, but not absolutely dependent upon. The primary consideration is the personhood of the working subject; the end or task is considered only in a secondary sense. Since the personhood of the worker is given primacy in wage determination, we can understand more fully why the popes going back to Leo XIII insisted on a living wage as something bound up with justice, with what is due to a worker by virtue of his dignity as a man who works.
This is not to say there is no place for calculations of a purely economic nature, or market conditions, etc. But it is to say that these material factors cannot be the sole or even the primary determinant in employer-employee relations. This echoes the teaching of John XXIII, who stated in Mater et Magistra:
"We consider it our duty to reaffirm that the remuneration of work is not something that can be left to the laws of the marketplace; nor should it be a decision left to the will of the more powerful. It must be determined in accordance with justice and equity; which means that workers must be paid a wage which allows them to live a truly human life and to fulfill their family obligations in a worthy manner" 
Returning to Laborem Exercens, John Paul II notes that the primary and secondary considerations in wage determination become perverted and inverted through what he terms "trends of materialistic and economistic thought" . In this perverted view of labor, "work was understood and treated as a sort of "merchandise" that the worker-especially the industrial worker-sells to the employer... the danger of treating work as a special kind of "merchandise", or as an impersonal "force" needed for production (the expression "workforce" is in fact in common use) always exists, especially when the whole way of looking at the question of economics is marked by the premises of materialistic economism" .
Again, this error is fundamentally an inversion of the subjective (primary) and objective (secondary) aspects of labor, in which the materialist objects of man's production are given more value than the man himself who produces. This inversion denies the fundamental truth that work is for man and not man for work. Furthermore, John Paul II gives a name to this inversion of valuation: "This reversal of order, whatever the program or name under which it occurs, should rightly be called "capitalism" .
The popes call for a return to the understanding that work is primarily a human act, that is, an act through which our humanity is manifested and even perfected, as to work is to image God the Father -"My Father worketh until now; and I work. " . When evaluating the whole question of work and the value derived from it, we must remember that it is not so much the skill set or product that makes work valuable, but the fact that man as the subject of work carries it out, and that all work must be ordered towards man's good. While skills, prevailing wages, market realities will always temper the value placed on a man's work, the primary value, the fundamental core from to which remuneration is ultimately attached, ought to be the personhood of the man, not his productive capabilities. To deny the latter aspect of man's role in work is to invert the two meanings of work as highlighted by the pope and create a situation in which man exists for work instead of work for man. Ordering the objective and subjective aspects of work properly ensures an authentically Christian approach to labor.
 John Paul II, Laborem Exercens 5, 1981
 "Work is one of the characteristics that distinguish man from the rest of the creatures, whose activity for sustaining their lives cannot be called work. Only man is capable of work, and only man works, at the same time by work occupying his existence on earth." (Laborem Exercens, Prologue)
 ibid., 6
 John XXIII, Mater et Magistra, 71
 Laborem Exercens, 7
 John 5:17