Robert Park's typology of marginal men is discussed in
Therivel's GAM/DP Theory of Personality and Creativity.

GAM's Marginal Men

GAM Leadsmen [Naipaul, Said, Cervantes, Montaigne, Marx, Freud, Napoleon, Endo] Are Not Parkian Marginal Men

The above is the title of chapter 1 of volume 4 of William A. Therivel's The GAM/DP Theory of Personality and Creativity (G stands for genetic endowment, A for assistances of youth, M for misfortunes of youth, DP for division of power, UP for unity of power). For an introduction to the GAM part of the theory click "Introduction to GAM"; for an introduction to the DP part click on "Introduction to DP".
In this website, the reader is also offered a shortcut: The GAM/DP Synopsis and an expanded version, The GAM/DP Summary of volumes 1 through 4.

This is a long and important chapter of which I report the table of contents and some pages.

This chapter is divided into the following sections:

I. Introduction
II. V.S. Naipaul
     1. The making of a leadsman
     2. As leadsman
III. Edward Said
     1. The making of a leadsman
     2. As leadsman
IV. Eminent Leadsmen of Jewish Origin
     1. Cervantes
     2. Montaigne
     3. Marx
     4. Freud
     5. Veblen's 1919 comments
V. Napoleon
     1. The making of a leadsman
     2. As leadsman
VI. Shusaku Endo
     1. The making of a leadsman
     2. As leadsman
VII. In the End

Introduction
     Marginal men, as described by Robert Park in his seminal article "Human migration and the marginal man" of 1928, are those whose personality is "a cultural hybrid, a man living and sharing intimately in the cultural life and traditions of two distinct peoples; never quite willing to break, even if he were permitted to do so, with his past and his traditions, and not quite accepted, because of racial prejudice, in the new society in which he now sought to find a place. He was a man on the margin of two cultures and two societies, which never completely interpenetrated and fused" (p. 892). The marginal man was characterized as suffering from "spiritual instability, intensified self-consciousness, restlessness, and malaise" (ib., p. 893). Then, as stressed by Leslie, Larson, and Gorman, 1973: "The lot of the marginal man is, thus, a lonely one. Unable to share fully in the way of any group, he may lack deep friendships and otherwise feel cut off from his fellows…. In extreme cases, these symptoms may be defined as those of incipient mental illness" (p. 88).
     Related to the marginal man, the GAM leadsman is a person with a high GxAxMxDP, for whom the misfortune of youth M (see table 1 of volume 1) is "rootlessness or uprootedness (e.g., forced conversion or assimilation of parents to the religious or ethnic ways of the majority; major changes of abode; major religious or cultural differences between parents). "The interaction of this misfortune with a high GxAxDP fosters the development of personalities who are: "detached; critical thinkers; relativistic; who often hold cosmopolitan and pragmatic attitudes." (Therivel, 2001, p. 41)
     I called the members of this personality family leadsmen because of their basic skepticism, of their constant need to check if things are as they are said to be. In this the leadsman is like the sailor who, at the prow of the ship, is responsible four sounding the depths of the water with a weighted line. He must ensure that the ship will avoid hidden rocks or treacherous sandbanks. Only after his "OK", will the ship go forward.
     This constant probing by the leadsmen makes them relativists, as was Einstein who discovered the relativity of our measurements in physics: space, speed and mass are interrelated, not fixed or independent values; as was Marx who asserted the relativity of our values, which depend on the means by which we make a living; and as was Freud who claimed the relativity of our motivations, based on our unconscious drives and forgotten youth.
     Closer to our times, Karl Popper said that "we must regard all laws or theories as hypothetical or conjectural; that is as guesses" (1975, p. 5), and Thomas Kuhn spoke of science(s) rooted in incommensurable and unprogressive paradigms.

     The leadsman is similar to the marginal man in some respects: "a cultural hybrid [or synthesis], a man living and sharing intimately in the cultural life and traditions of two distinct people … a man on the margin of two cultures and two societies, which never completely interpenetrated and fused." However, for the leadsman it is not true that he is "never quite willing to break, even if he were permitted to do so, with his past and his traditions, and not quite accepted, because of racial prejudice, in the new society in which he now sought to find a place."
     First, the leadsman rarely feels the need to break from his past and his traditions because, thanks to his high GxAxMxDP, he built his own life, his own past and traditions. Secondly, his talents and creativity make him accepted, if not immediately and not completely, still to such a high degree that he does not need more. Thirdly, the lot of the leadsman is not a lonely one, with the exception of the solitude he has chosen himself in order to be creative. Yes, from time to time, he may feel cut off from his fellows, but he also knows that that is the price he has to pay to be creative.
     The list of eminent leadsmen of the past is a long one, including Cervantes, Napoleon, Marx, and Freud, whom I will discuss further on. However, there are two eminent contemporary leadsmen whom we should study first, because they have written extensively about both their youth and the world around them: V. S. Naipaul and Edward Said.