The Discovery of the Soul as a Place of Pilgrimage within: German Protestantism, Psychology, and Salvation through Education

Abstract

This article casts a spotlight on various stages of the entangled history of German Protestantism and psychology from the 16th to the 19th centuries to make visible the hitherto neglected religious past of this discipline and the educational aspirations tied to it. In broad strokes, it retraces how the idea of psychology emerged in the wake of the Reformation and continued to be shaped by German Protestant thinkers for centuries to come. First, the article reconstructs how, after Luther, the term “psychology” came to denote Protestant attempts to construct a non-Catholic scientia de anima. The dissemination and popularization of this endeavor in the writings of German Protestants is discussed in the second section. The third and fourth sections are devoted to shifts in reasoning about the soul during the early German Enlightenment and the subsequent flourishing of attempts at establishing psychology as a scientific discipline in its later stages. Finally, the last section looks at the further “scientification of the soul” during the 19th century, which, as will be argued, was crucial to the constitution of the modern educational field in Germany.

1. Introduction

The Christian doctrine of justification asks what must happen in order for the relationship between man and God, which has been burdened by man’s sins, to be restored to order. Martin Luther’s answer was that man himself cannot actively contribute to this, but he is dependent on divine grace, which Luther related to man’s faith (sola fide). In this way, he expressed the conviction that man attains eternal life by his faith alone and, here the second principle, that his faith is strengthened by reading the Holy Scriptures, the Word of God, which speaks to the soul of the believer (sola scriptura). Faithfully reading God’s words connects the innermost part of man’s soul with God. The human soul thus became the locus of divine guidance over scripture-guided faith and thus a central object of religious interest, belief, and hope in German Protestantism. In the course of the following centuries, various doctrines were developed around this soul, which—also falling increasingly under the term of psychology—was considered to be “scientifically” explorable and made it the object of human knowledge, understanding, and intervention.

Contrary to prevailing narratives in the historiography of psychology that sideline psychology’s religious past (see, e.g., Hothersall and Lovett 2022; Brennan and Houde 2023), we intend to show that “modern” psychology became a specific mode of understanding of man in the wake of the Reformation and continued to be shaped by Protestantism in the centuries to come—including in 19th-century psychology.1 We argue that the significance of the Protestant imagination of the soul and the idea of inner salvation, as it was conceived within Protestantism, have not disappeared but live on, albeit transformed, in other guises, such as in the university-based scientific discipline of psychology, which is notoriously unhistorical and ignores its historical religious roots. Psychology and, by association, prevailing ways of educational reasoning, which see working on one’s own inner self as the way to the improvement and salvation of mankind, are in this sense long-term but buried consequences of the German Reformation. To support this claim, we cast a spotlight on various stages of the entangled history of German Protestantism and psychology from the 16th to the 19th centuries and ask how this has affected scientific and educational aspirations. First, we will reconstruct the role attributed to the “soul” in German Protestantism and how the notion of psychology emerged in Protestant debates of the 16th and 17th centuries. Not only does the word “psychologia” figure prominently in the writings of Protestant theologians, but they also first envisioned psychology as a science of the human soul. This notion of psychology as a specific field of knowledge that has the (immaterial, immortal) human soul as its object was further disseminated and popularized in Protestant institutions and the writings of Protestant scholars throughout the 17th century, as will be exemplified in the second section. In the third and fourth sections, selected examples are used to point out how, in the context of the German Enlightenment of the 18th and early 19th centuries, the theological framework slowly began to recede into the background while the notion of psychology as a means to understanding and guiding the soul “scientifically” gained more and more ground. The fifth and final section of the article explores the further “scientification” of psychology in the 19th century, which continued to wrest its expert status and claim to the soul from theology while at the same time preserving the soul as the main target of (educational) intervention and thus paving the way for “modern” education in Germany.

Regardless of the theological and scientific camps that formed and fought among themselves for recognition, the various “psychologies” shared the same basic assumptions: (1) The human soul exists as an immaterial condition/reality; (2) there is a way to know the soul (scientifically); (3) the place of salvation or improvement lies within the individual soul (or later mind/spirit), and (4) ultimately, this salvation or betterment can be implemented through education. What changed over the centuries was that Luther’s fundamental pessimism, which owed much to his deep conviction of original sin, transformed and gave way to an optimism that triggered and inspired the scientific obsession with understanding and improving the inner self, and thus, while not replacing the religious fixation on the redemption of the soul, wrapped it in the cloak of scientism.

In the retrospective narrative, the history of psychology’s Protestant past, of course, appears much simpler, more linear, and more clear-cut than the complex reality of a centuries-long development could ever be. While holding to the thesis that “psychology” is closely related to Protestant understandings of the soul, it cannot be said that this quasi-idiosyncratic connection of Protestantism and the psychological soul was fixed from the beginning, nor can it be claimed that Catholicism had no part at all in shaping this understanding of the soul. Psychology did not logically or inevitably follow from Protestant theology. Rather, the emergence of the Protestant understanding of the soul was influenced by the very fact that it was designed to be anti-Catholic (in particular anti-Thomistic) and that, vice versa, Protestantism, in the sense of confessionalization research, also configured itself through its continuous demarcation from its “Catholic other” through the clarification of the concept of soul. The “Protestant–psychological” understanding of the soul, brought about by these confessionalization processes, was not simply met with rejection in Catholic circles but also with interest, which further spurred its popularity. In this context, an epistemological change can also be identified, which, in the transition to the 18th century, led from earlier rationalism to empirical science and, in the 19th century, finally to experimental science. This change was not absolute and was partly sharply criticized also within Protestantism, especially from the tradition of German education, which as a rule strictly followed the non-empirical conviction. With some delay, the Catholic “opposite side” was also able to get involved foremost in what came to be called empirical psychology,2 more so as its Protestant origin was more and more forgotten under the seductive power of laboratories and empirical research methods.

2. Confessionalizing the Soul: Martin Luther’s Dual Nature of Man

In the year 1517, the Augustinian monk Martin Luther launched an attack on the Roman Catholic Church from the small German town of Wittenberg that, while not the first of its kind, was arguably the most sustained up to that time. The criticism of many of the Church’s central doctrines associated with this attack and the conflicts that followed were to change not only the religious but also the political and scientific landscape in Europe.

As is well known, Luther rejected the sale of indulgences and the belief in good deeds as a path to salvation, which he, in contrast, tied solely to God’s grace and faith alone. It is equally recognized that Luther’s claim that the Bible is the only source of divine knowledge challenged the institutional power of the Catholic Church in general and the Pope in particular. In connection with Luther’s assertion of sola scriptura and sola fide, however, the hitherto established theological–philosophical approach to the question of the soul was also called into question. At the time, discussions around the soul were traditionally in the form of commentaries on Aristotle’s De Anima and ecclesiastically backed up by papal decrees. By the beginning of the 14th century, the Roman Catholic Church’s Council of Vienne (1311–1312) had elevated Aristotelian hylomorphism to the status of Christian orthodoxy by condemning as heretical the claim that the “intellective soul of man is not the form of the human body of itself and essentially” (Decree 1, p. 361). This definition was reinforced again two hundred years later during Luther’s lifetime by the Church’s Fifth Lateran Council (1512–1517) in Rome, which emphasized that the “soul truly exists of itself and essentially as the form of the human body.” Accordingly, the Council called upon the philosophers teaching at universities to espouse this “truth of the Christian religion” against “odious heretics and infidels who are undermining the Catholic faith” (Fifth Lateran Council 1513, Session 8, p. 605).

In Aristotelian philosophy, in which an entity is made up of “form” and “matter,” the soul has been understood as a general form of all living beings that “enforms” matter in such a way that a being with the potential of “being alive” is created. An often-invoked metaphor to explain this relationship is that form and matter make up a being, just as a particular shape and bronze make up a statue. This intimate entanglement of soul and body runs counter to considering them as separate entities, and, consequently, commentaries on De Anima lacked a clear distinction of what today might be called “psychology” and “physiology.” In this context, not only humans but all living beings were thought to be ensouled, and the scientia de anima was accordingly designed as a general science of all living beings of which man (as animal rationale) was only the noblest one. Propelled by Thomas Aquinas’ synthesis of Aristotelian philosophy and Christian theology, this had become the accepted framework within which—precisely until Luther’s theological and ecclesiological protest—most discussions about the soul had taken place (de Boer 2013).

Among other issues, it was this alliance of Aristotelian philosophy and the Christian faith, sanctified by Aquinas and the pope, that irritated Luther and spurred his protest, to which Pope Leo X responded in 1520 with Exsurge Domine, threatening Luther with ex-communication. Instead of backing off, Luther doubled down on his criticism and penned multiple responses to the papal bull, in some of which, the “appropriate” understanding of the soul was a key motif. Mocking the authority of the papacy, Luther dismissed, for example, the belief in the soul as a form of the body (as opposed to the soul as a purely inner entity) as being simply one of “all those endless portents in the Roman dunghill of decrees” (Luther [1520] 1897a, p. 132). In that same year, he also demanded a ban on many of Aristotle’s writings, including his De Anima:

The fact is that whatever the papacy has ordered or instituted is only designed for the propagation of sin and error […] very little is taught of the Holy Scriptures of the Christian faith, and the blind heathen teacher, Aristotle, rules even further than Christ? Now, my advice would be that the books of Aristotle, Physics, Metaphysics, Of the Soul, Ethics, which have hitherto been considered the best, be altogether abolished.

(Luther [1520] 1888, p. 457)

Luther’s rejection of scholastic philosophy in general and the Christian–theological use of Aristotelian philosophy in particular arises from the principles of justification by faith and scripture alone, which give particular weight to the knowledge of the soul as the immortal and thus most divine part of the human being. The so-called Freiheitsschrift (1520), which is today considered one of the central German Reformation texts, is a testimony to the importance attached to the soul in Lutheran theology. In this treatise, Luther set forth his understanding of freedom in a Christian sense by elaborating on the dual nature of the human being. He wrote:

[E]ach Christian is of a dual nature, spiritual [geystlich] and physical [leyplich]. As to the soul, he is called a spiritual, new, inner person; as to flesh and blood, he is called a physical, old, and outer person […] nothing external can make him either free or righteous, however you may call it, since righteousness and freedom, and conversely evil-doing and imprisonment, are neither physical nor external.

(Luther [1520] 1897b, p. 21)

Instead of the, until then, assumed hylomorphic unity of soul and body, Luther asserted that there was a stark dualism between the “inner, free, spiritual man” assigned to the soul and the “outer, subjected, physical man” assigned to the body. The Word of God speaks in the soul to the faithful, who is free in this respect, while the body, which is limited to carrying out external acts, is subject to worldly laws. This dualism applied to the Church as well. When characterizing the Roman Catholic Church as an institution in which a clerical class performs only outward works, Luther argued that it had “a secular, outward, grand, fearsome dominion and power” (ibid., p. 17). The Catholic Church stood in contrast to the true priesthood of all believers united in inner faith. This makes it particularly vivid how central pillars of Lutheran theology revolve around the fundamental polarity of the inner, spiritual soul on the one hand and the external, material body on the other.

Of particular interest here is that, although the soul plays such an important role in Luther’s writings, he did not provide a systematic explanation of his concept of the soul, let alone a treatise on how it differs conceptually from the established understanding of the soul that he so zealously rejected. Together with the fact that the soul is invoked in contradictory or ambiguous ways in Luther’s various writings (see, e.g., Wolff 2008; Dietz 2015), this makes it difficult to pin Luther down to a clear definition of the soul. The only thing that is certain is that the soul is immaterial, unattached to the material world, related to God, and therefore of the highest dignity. But it was precisely this fundamental dualistic determination, together with the conceptual indeterminacy of the Protestant understanding of the soul coupled with the explicit rejection of the Catholic Church’s understanding of the soul, that consequently triggered a wave of attempts at clarification, some of which were to adopt the new label of “psychology.”

3. The Early Formation of Psychology as a Protestant Science of Human Nature

Luther openly opposed the Catholic–Aristotelian conception of the soul in light of his own conception of an inward, spiritual soul, representing the highest, inner worthiness of man, which does not require any institutional mediation by the (Catholic) Church for the human experience of salvation. However, in keeping with his doctrines of sola scriptura and sola fide, he did not develop a systematic counter-doctrine to the soul. The lack of a consistent Lutheran doctrine of the soul left a kind of vacuum that paved the way for numerous interpretations of the soul in the wake of Luther and set the forming Protestantism on a quest of developing a “non-Catholic” doctrine of the soul.

Perhaps the most important scholar who influenced Protestant treatises on the soul in the wake of Luther, and who has sometimes even been credited with first using the neologism “psychology,”3 is Phillip Melanchthon. Melanchthon initially shared his friend Luther’s hostility towards scholastic philosophy and his campaign to ban Aristotle from the University of Wittenberg (Kusukawa 1995, pp. 33–48). However, amidst the rise of counter-attacks against Luther and the urgent need to distinguish his cause from other even more radical movements (most notably the Anabaptists, who were blamed for the German Peasant’s Revolt), Melanchthon had to clarify Luther’s theology and was forced to use philosophical arguments to do so. When Melanchthon was tasked with reforming universities and schools in the German Protestant lands in 1526, he restructured the teaching of natural philosophy and himself wrote a commentary on Aristotle’s De Anima—which differed from previous commentaries in that he reconfigured the scientia de anima in terms of a Lutheran view of human nature (ibid., pp. 79–88; Cellamare 2015). His scientia de anima was not a general science of life anymore, but the science of the divinely ordained dual nature of man, in which man was not an animal rationale but consisted of a body (with its own material reality) and a soul (which was redefined as immaterial and immortal spiritus intelligens).4 Melanchthon’s commentary played a decisive role in shaping, at least, higher Protestant education and was thus able to popularize his approach to the soul: His Liber de Anima (1552), published six years after Luther’s death, went through more than sixty editions by the end of the 16th century and became the standard textbook on the soul taught in Protestant milieus (Gábor 2008, pp. 87–90; Kessler 1988, pp. 516–18).

In the 16th century, confessional identities were not yet rigid but were in the process of forming, and it is from these that the notion of “psychology” would arise. As Kusukawa (1995) or Cellamare (2015) have pointed out, Melanchthon’s efforts to establish a Lutheran science of the soul (as well as other controversies related to the soul) were both an instrument and a result of confessionalization processes that would, among others, shape confessional demarcations in the “proper” understanding of the soul. Melanchthon’s Liber de Anima was rarely read by Catholics, but both Lutherans and Calvinists used it as a main reference point, driving the development of a science of the human soul that was categorically distinct from the sciences of natural bodies. In this process, the word “psychology” became popular, expressing the new, i.e., Protestant, way of reasoning about the soul (Gundlach 2012; Lamanna 2010; Mengal 2000, 2005).

An illustrative example of this is the Marburg professor Rudolph Goclenius (1547–1628), who was a former Lutheran who had converted to Calvinism and based himself on Melanchthon writings. In 1590, Goclenius published an edited volume in which he wanted to assess the status quo of the Protestant doctrine (or science) of the soul—which he titled Psychologia, hoc est de hominis perfectione, animo et in primis ortu hujus (Psychology, This Is About the Perfection of Man, His Soul and, Above All, His Origin; 1590). One of his students, Otto Casmann, published the book Psychologia anthropologica, sive animae humanae doctrina (Anthropological Psychology, or the Study of the Human Soul; Casmann 1594), in which he argued that the science of man ought to consist of two parts, psychology and anatomy, which coincide with the two parts of man, the incorporeal and immortal soul and the body, governed by the soul (e.g., pp. 22–24). Casmann thus reinforced the motif of the soul–body dualism and affirmed the need for a separate science of the human soul bearing the name psychology. He, too, openly challenged the hylomorphic definition of the soul advocated by the Catholic Church from a theological point of view (pp. 2–5) and justified Melanchthon’s “Lutheran revision” of De Anima against public attacks, for instance, by the Catholic theologian Julius Caesar Scaliger5 (ibid., pp. 60–63). Rudolph Snellius, still another of Goclenius’ students and teaching at the Calvinist Leiden University, published a work on the soul, titled In Avrevm Philippi Melanchthonis De Anima…Theses quaedam ac disputationes de praecipuis materiis Psychologicis selectissimae (The Extraordinary Melanchthon’s De Anima, Certain Theses and Discourses on the Principals of the Most Important Topics of Psychology; Snellius 1596), that promoted the spread of Protestant psychology in the Netherlands. Like Casmann, Snellius divided his book into two sections mirroring “the two parts of man” (p. 5), but he dedicated most of his attention to anatomy and the workings of the living body and not to the soul. The body, in turn, is not treated “for its own sake,” but as the instrument that allows the soul to act. While being the origin of all bodily movement (p. 227), the immortal soul, Snellius insisted, has “not the least in common with elements and bodies made from concrete elements” (p. 22) but instead “conforms to God himself” (p. 320).

These few contributions of long-forgotten scholars in the later 16th century show the struggle for a more precise conception of “soul,” which was understood primarily in an anti-Catholic way and as such was to be brought to term. Protestant psychology was less a unified research program that necessarily followed from Luther’s theological doctrines, but rather a series of attempts by Protestant theologians to think about the soul differently than their Catholic counterparts. This process of confessional demarcation was not homogeneous and lasted for decades, which is evidenced by the early, psychological literature that was still full of negotiation processes with and remnants of the Catholic–Aristotelian framework while at the same time struggling for its own Protestant clarity.

Regardless—or maybe precisely because—of this heterogeneity, by the middle of the 17th century, the name “psychology” had become so well established for the (Protestant) study of the soul that it could be found in dictionaries such as the Lexicon philosophicum (Micraelius 1653, p. 930), published by the Lutheran theologian Johannes Micraelius. By this time, both the word “psychology” and the underlying dualistic view of man had even crossed confessional boundaries and were accordingly not only found in the different Protestant circles but also, albeit to a clearly lesser extent, in Catholic writings (Mengal 2000, pp. 12–14). This was, however, not the end of the influence of German Protestantism on the development of psychology as a scientific discipline, quite the contrary. The early phase of the German Enlightenment was to play a pioneering role in psychology’s further development, especially with regard to the idea of the potential perfectibility of the soul’s inwardness detached from the precarious material outside world.

4. Psychology in the Early German Enlightenment

The conceptual clarifications that had become necessary in the wake of Luther’s vehement determination that the soul was non-bodily and his simultaneous refusal or inability to determine the soul as a soul conceptually had, over about 130 years, paved the way for an understanding of the soul to prevail that supported Protestantism doctrinally as much as Protestantism was the basis of this understanding of the soul in the first place. These generally intra-theological clarifications were then taken up in philosophy in the course of what is called the early German Enlightenment, which at that time separated itself more strongly from theology, that is, in the period after the Peace of Westphalia. This is the time in which the existence of an inner soul, independent of the body, was unquestioningly presupposed, but, due to theological reservations, it was still not considered to be entirely explicable rationally. However, the soul—or rather, its manifestations—were slowly opened to a more empirical approach in what might be translated as “experiential psychology,” which would then, in the 19th century, be replaced by “experimental psychology,” which, to some extent, no longer thought it even needed the idea of the soul. In this process, ideas of education developed that are still effective today.

One of the most influential scholars was probably the mathematician and natural law expert Samuel von Pufendorf (1632–1694), the son of a Lutheran pastor and himself a student of Lutheran theology and jurisprudence. Pufendorf wrote a seminal work on natural law against the backdrop of the Confessional Wars, De jure naturae et gentium libri octo (On the Law of Nature of Nations: Eight Books; 1672), which he understood as an empirical science (Von Pufendorf 1672). In it, the tight connection between the human soul, human reason, and human dignity becomes clear:

The Dignity of Man and his Excellency above all other parts of the Animal World, made it requisite that his Actions should be squar’d by some Rule; without which no Order, no Decorum, no Beauty can be conceiv’d. Hence it is, his greatest Honor that he has obtain’d an Immortal Soul, indu’d with the Light of Understanding, with the Faculties of judging and of chusing things, and with an admirable Capacity of Arts and Knowledge.

(Von Pufendorf 1703, p. 76)

This was in line with Pufendorf’s previous writing that “Man is of the highest dignity because he has a soul, which is distinguished by the light of reason, by the ability to judge things and to decide freely, and that is familiar with many arts” (Von Pufendorf 1672, p. 136).6 In this Protestant way of defining the dignity of man, it is precisely the individual’s soul that is the pivotal point—and not its connection to the human body or “Holy Mother Church” as it would have been in Catholicism. In Pufendorf’s Protestantism, it is the soul of man or the reasonableness of human nature, conceived as the noblest part of this soul, which distinguishes man as man. It establishes the essential equality of all human beings, which is precisely rooted in the universality of understanding/reason and the immortality of the soul (Wildfeuer 2002).

Thus, from a rationalist point of view, the soul was partly emancipated from theology and defined in philosophical–psychological terms. It was not connected with the body, but it could still be experienced, not sensualistically, however, but inwardly. Following Pufendorf, it was primarily Christian Wolff, another natural law philosopher, Lutheran theologian, philosopher, and lawyer, who would shape the further trajectory of German psychology. In his so-called German Ethics (Vernünfftige Gedancken: Von der Menschen Thun und Lassen, zu Beförderung ihrer Glückseeligkeit), published in 1720 (Wolff 1720), Wolff discusses rules of good human action in terms of happiness, arguing rationalistically insofar as only the “knowledge of the good … is a reason for the motion of the will” (§. 6). The guiding concept is the perfection of life: “Do what makes you and your or others condition more perfect; refrain from what makes it more imperfect” (§. 12). Besides the perfection of the body, the external (äußerlich) existence of the human being, Wolff is primarily concerned with the inner perfection of the soul, for which knowledge of the self is essential (§§. 224–225). He further elaborates on this in German Metaphysics, in which he dwells on “Reasonable thoughts of God, the World, and the Soul of Men” (which is the precise title of the book). In the first two chapters of this work, which deal with epistemological questions, Wolff argues that (self) consciousness is the foundation of all cognition. The third chapter continues experientially by defining inward experience: “Of the soul in general, namely what we perceive of it” (§. 191). Here, Wolff is explicitly unconcerned with definitions of the soul (this unempirical part of his psychology follows only in the fifth chapter at the very end of the oeuvre), but with experience, of “what we perceive of it through daily experience” (§. 191). For this, no elaborate science is needed but only the “attentiveness” of each individual to him or herself, from which “some important” or even “infallible truths” can be derived (§. 191). The soul is thereby—and this is explicitly directed against Descartes’ epistemology—the instance that is “conscious of itself and other things besides itself,” but only if “we are conscious of ourselves and other things besides ourselves” (§. 192). This self-conscious self is the soul and vice versa (§§. 195–197), and this is the basis of clear cognition, which is thus always also “deep insight” (§. 209) because the soul is deep in man. Psychology (in German: Seelenlehre, the doctrine of the soul) is the psychology of (self)-consciousness, as it combines the inner self, self-reflection, and knowledge and focuses on the description of the mental capacity or faculty of the soul.

Although Wolff may not have ascribed scientificity to this experiential kind of knowledge—science is rational, not empirical (§. 371)—in 1732, he published an entire work in Latin on experiential (inductive or descriptive) psychology, his Psychologia Empirica, which he then followed with a treatise on rational (deductive and explanatory) psychology, Psychologia Rationalis (1734). Wolff wrote these influential books while teaching at the Protestant University of Marburg, the same university where, about 150 years earlier, Goclenius had worked and first popularized the term psychology. And just as with Goclenius’ (1590) Psychologia, Wollf’s Psychologia Empirica and Psychologia Rationalis both went through many editions and were received throughout Europe. Both psychologies dealt with one and the same subject, the soul, which could be treated in two ways: The rational study of the soul deals with the essential perfectibility (perfectio essentialis) of the soul, and the empirical study deals with the accidental state of the realization of this perfectibility (perfectio accidentalis) that individuals may or may not be realizing in their respective conditions of life (Wolff 1736, pp. 528–30). This close connection between the Protestant notion of the immaterial soul and the idea of the (inner) perfection of the human being would also shape subsequent debates about psychology and education.

With his dual approach, Wolff had great success, especially in Protestant Germany, where empiricism was never categorically separated from metaphysical certainty but always operated within its normative framework. Wolff’s double scientific approach to the soul, first with a rational “theoretical science” aiming at the understanding (of the essence) of the soul, and then with an “empirical science” producing experiential knowledge about the soul by introspection, was further developed by his successors, so that—in the 19th century—even a split of both approaches occurred.

One of the “further developers” of the double approach was Alexander Gottlieb Baumgarten, one of the very well-known German Enlightenment thinkers, who was also the son and brother of Lutheran theologians and educated in the Pietist Orphanage in Halle, Wolff’s student in Jena, and “father” of what can be called the philosophical sub-discipline of aesthetics in Germany. In his Metaphysica (Baumgarten [1739] 2013), Baumgarten defined psychology in Wolffian terms as a science of the soul that derives its knowledge both from rational deliberation as well as from introspective experience. He further elevated psychology to a foundational science that could provide the “first principles of theology, aesthetics, logics, and the practical sciences” (§. 502), which indicates a certain reversal where psychology was no longer derived from theology, but rather theology rested on psychological principles.

5. Psychology in the Late German Enlightenment

The status and shape of psychology as a science were still being negotiated and remained controversial in the decades following Wolff and Baumgarten. Immanuel Kant, for example, was famously skeptical about the project of scientific psychology. He argued against empirical psychology by saying that its method is limited since inner experience, like all experience, allows access only to the world of (subjective) appearances: Through introspection “I recognize myself only as I appear to myself, not as a thing in itself” (Kant [1798] 2003, p. 28). Rational psychology was also deemed as unable to grasp the soul as it really is since it is based on the inherent contradiction of claiming to comprehend the soul beyond any experience, while necessarily falling back on the inner experience of thinking (Kant [1781] 1998, pp. 441–48). Consequently, through no scientific approach, “whatever it may be, can anything be known of the nature of our soul, which concerns the possibility of its separate existence” (p. 459). For Kant, the immortal soul as well as God are not objects of knowledge, but morally necessary postulates of faith and morally good conduct (pp. 784–92, 855–59).

Kant’s reservations, however, apparently did not lead to the abandonment of attempts to establish psychology as a science, quite the contrary. The development of modern science, especially in England and France, towards which Kant was skeptical throughout his critical work, triggered the ambitions of intellectuals to get to the bottom of the soul with scientific methods, albeit German reformulated, i.e., as a metaphysical, inner experience rather than a sensual one7. One prominent attempt was the so-called Erfahrungsseelenkunde (empirical psychology, or, literally, empirical soul studies), championed by Karl Philipp Moritz, a German author who grew up in a quietist–pietist milieu and briefly studied theology himself. Together with the Jewish intellectuals Salomon Maimon and Carl Friedrich Pockels, another author born into a family of Lutheran pastors, Moritz edited the Magazin für Erfahrungsseelenkunde (Magazine for Empirical Soul Studies; Moritz et al. 1783–1793), which is considered to be the first psychological journal in Germany. For the first issue, Moritz publicly called for “all lovers and promoters of benevolent knowledge and science” (Moritz [1782] 1999, p. 793) to send in self-observations and biographical stories that could promote the project of a soul-science constructed from (inner) experience so that “the human race could become better acquainted with itself through itself and rise to a higher degree of perfection, as the individual person becomes more perfect through knowledge of themselves” (p. 796). While previous observations of man were “merely taken from the surface, and not lifted out of the innermost part of the soul” (p. 800), the new science of the soul was to be based on deliberate and self-disciplined introspection and thus able to provide self-knowledge that would serve the education of the individual and of humanity as a whole.

In Protestant Germany in the 18th century, attempts at establishing a psychological “science” mushroomed. They differed in their concrete methodological dispositions but shared a fascination with the inner soul as a place of salvation—or, increasingly rendered in educational terms, as a place of individual perfection. This is mirrored in the educational writings of the German intelligentsia after 1750: Whether empirical (experiential) psychology was praised as self-education through the self-reflection of daily experiences (e.g., Moritz et al. 1783–1793) or psychology was appointed as the scientific foundation of the German enlightened education theory (e.g., Lieberkühn 1782; Trapp 1780), in the German educational literature of this period, the nexus between soul, psychology, and education was a crucial motif. And so it was to remain in the following century; a century in which the theological framework of the soul was to increasingly take a back seat to an increasingly (but superficially?) secularized psychological soul.

Notwithstanding that Kant had called the study of the soul non-scientific, intellectuals around and after 1800 attempted to finally get a handle on the soul. Completely stuck in the Protestant tradition, the inner experience was supposed to guide the way, which was now to be rationalized with new tools and was with the most rational of all tools, mathematics. Kant’s successor in Königsberg, Johann Friedrich Herbart, for example, postulated that a scientific rational psychology was indeed possible; the only problem was how to explore introspection methodically on a rational–mathematical basis. He thus formulated his own approach to studying the soul mathematically in two publications, On the Possibility and Necessity of Applying Mathematics to Psychology (1822) and Psychology as a Science Newly Founded on Experience, Metaphysics, and Mathematics (1824).

On the basis of his psychology, Herbart developed a systematic theory of learning and teaching in his Umrisse pädagogischer Vorlesungen (Outline of Pedagogical Lectures; 1841), the so-called formal stage theory, which was to lead the way for the development of German education and school pedagogy throughout the 19th century. According to his doctrine, the two phases comprising four formal stages of learning were the deepening phase, with the stages of clarity about prior knowledge and association as the assimilation of new knowledge, and the reflecting phase, with the stages of incorporating the new knowledge into the stock of the old and practicing it. This became the canon of school instruction, not least in teacher education. Herbartianism was canonized in the last third of the 19th century by the former Lutheran theology student and teacher seminary director Wilhelm Rein with his eight-volume work, Theorie und Praxis des Volksschulunterrichts nach Herbartischen Grundsätzen (Theory and Practice of Public Education According to Herbart’s Principles; 1878), and his seven-volume Encyklopädisches Handbuch der Pädagogik (Encyclopedic Handbook of Education; 1895), which was followed by a second edition in eleven volumes (1903).

6. The “Scientification” of the German Soul

For the organization of German elementary school education, Herbart’s mathematical psychology seemed to be sufficient, but it did not satisfy the thirst for knowledge about the actual “inner life” of the soul. Herbart had provided a (rational–mathematical) model for the abstraction of the inner experience of the soul, but he could not give an answer to the question of how the human soul could be understood as such on a supra-individual level. The empirical research of the soul, therefore, demanded other means, and of the two competing modern methods, (passive) observation and (active) experiment (Daston and Lunbeck 2011), only the latter suggested itself for obvious reasons. Experimentation was to produce a different quality of empirical knowledge than mere individual experience abstracted by mathematics.

The model for experimental research was found—of all things—in French physiology, which, in the 18th century, detached itself from anatomy due to its research methods (Danziger 1990, pp. 24–27). The pioneers of this model had been people like the French medical doctor François Magendie, who had tried to verify general ideas about the phenomena of living bodies, i.e., most physiological matters of fact, through experiments that should lead to statistically corroborated facts that did not need to be interpreted. These methods of sensory physiology were now imported to the ongoing German debate on the scientification of the soul with the assumption that they could be applied to the soul in order to discover certain hidden functions.8 The idea was to expose a “system”—in French physiology, the body, in German psychology, the soul—to different stimulations to see how it “worked.” Thus, research became a matter of the functional dependencies of sensitive—or introspective—experience under the conditions of stimulation, whether in terms of intensity, spatial localization, or temporal duration.

Against this background, the experimental approach to psychology for a long time came to be called “physiological psychology,” and the corresponding research was accordingly often carried out by physicians, as, for example, by Friedrich Wilhelm Hagen in his Studies in the Field of Physiological Psychology (1846), even though many of these publications were for a long time still subsumed under “philosophy” in the library classification. Behind this was a dichotomy of research, which subsequently became apparent in the fact that one part went in the direction of research into diseases and thus psychiatry, which was carried out by physicians. On the other hand, there were a considerable number of researchers who did not simply aim at curing diseases but wanted to understand the soul and its “secrets” even better. A very considerable or strikingly high number of these researchers were sons of Protestant ministers.9

The first psychological law, formulated on the basis of experiments in the middle of the 19th century, came from the physiologist Ernst Heinrich Weber and physician Gustav Theodor Fechner, both of whom had come from a Protestant parsonage and had studied quantitatively how humans respond to various physical stimuli. This Weber–Fechner law was to be groundbreaking for further research in the 19th century, not least for the supreme father of physiological psychology, Wilhelm Wundt (Wundt 1920, p. 301). He was the founder of the first, world-famous psychological laboratory in Leipzig in 1869, and he attracted dozens of students from all over the world to write their doctoral theses with him, among them, to begin with, were a great many Americans from devout Protestant backgrounds (Tinker 1932). Wundt, for his part, also came from a Protestant parsonage, as did the founder of the second psychological laboratory, which was established in Göttingen in 1887, Georg Elias Müller. The rise of experimental psychology was a clearly Protestant domain that used physiological research methods for the study of the soul.

In the last quarter of the 19th century, resistance gradually arose to the explanatory power that physiological research methods could generate about the human soul. Here, too, it was the sons of Protestant ministers who now again emphasized the rational part of the soul more strongly and paid far greater attention to the inner world of experience, which, in their opinion, could not be grasped by physiologically based experiments. They had a different method to offer than what the French physiologists had developed, and that was hermeneutics, the original Protestant art of textual interpretation, which was now applied to the whole world of the mind (Geist) and its forms of expression.

The indisputably most important and probably also most enduring representative of this anti-scientific (in the sense of the natural sciences) exploration of the soul was Wilhelm Dilthey, (1833–1911), son of a Calvinist preacher, who himself had studied Protestant theology and became a professor of philosophy. As an alternative concept to the ever more dominant natural sciences, which now threatened as a methodological arrangement to still determine the soul of man, Dilthey developed a “life-philosophical” alternative, which no longer explained human life and the forms of its expression only according to natural laws, but rather sought to understand the inherent lawfulness of human spiritual life. As early as 1883, Dilthey developed the program of refounding those sciences, which had been fragmented into separate parts and were related to the mind and life of human beings, under the name of Geisteswissenschaften (humanities).

The trend of contrasting the isolation of the sciences and the rise of the natural sciences with an alternative owes much to what Dilthey called the “historical school.” This is seen as a (German) reaction against the developments in France (natural law, political economy, etc.), which resulted in the French Revolution and dissolved the Holy Roman Empire of the German Nation in 1806 (defeat by Napoleon). In this context, the historical school had developed “a view (Anschauung) of historical growth,” which was interpreted as a process in which “all spiritual (geistige) facts” arise—and in which the Anschauung brings to light the untruth of the French system (Dilthey [1883] 1959, pp. XV–XVI). What Dilthey wanted to establish was to give this historical school an epistemological foundation and a method, hermeneutics, in which it was not metaphysics that should be the starting point but the “inner experience,” the “facts of consciousness.” Here, it becomes clear how he wanted to reinterpret Kant against the background of this historical school, aiming at the clarification of the conditions of inner experience. “All science is experiential science,” Dilthey affirms, but experiences are possible only against the background of an original pre-empirical, coherent context of experience anchored “in the conditions of our consciousness,” behind which, no one can look (p. XVII).

With this in mind, it is not surprising that Dilthey also turned to psychology and sharply criticized the dominant orientation of psychological research in the laboratory. The claim of the currently dominant, i.e., “explanatory” or “constructive”, psychology was, Dilthey argued, to establish a causal connection that was to make all phenomena of the life of the soul comprehensible and that attempted to solve this claim by the same means with which physics or chemistry explain the physical world. The idea of this explanatory method ultimately derived from atomistic physics, and explanatory psychology accordingly sought “to subordinate the phenomena of the life of the soul to a causal connection by means of a limited number of clearly determined elements” (Dilthey [1894] 1957, p. 139). This goal required a connection of hypotheses. The concept of a hypothesis can be conceived in different ways, but it is always a conclusion based on the induction of an experiential concept, which contains an expectation “which extends beyond the given to the not-given” (p. 140). All experimental psychology requires these hypotheses.

In contrast to the justification of the representatives of explanatory psychology to use hypotheses based on the model of the natural sciences, Dilthey proclaimed that the humanities should use their own methods, which should be determined independently according to their object. While the natural sciences have as their object facts “which appear in consciousness as from outside, as phenomena and individually given,” the objects of the humanities, in contrast, appear “from within, as reality and as an original living connection” (Dilthey [1894] 1957, p. 144). This leads to the fact that the natural sciences are indeed to be found “only by supplementary conclusions, by means of a connection of hypotheses, in the context of nature” while, however, the context of the life of the soul “as an originally given one” is already there, given, existent; that is, it does not even have to be searched for, constructed, and explained, but “merely” understood. “Nature we explain, soul-life we understand. … The experienced context is here first, the distinguishing of the individual parts of it is the subsequent” (ibid., p. 144).

Consequently, a psychology appropriate to the essence of the soul is not an explanatory but an understanding one, to be found in the living context of the innermost part of the soul and its cultural expressions. “An empiricism which renounces the grounding of what happens in the spirit [Geist], from the understood context of spiritual life, is necessarily barren” (Dilthey [1894] 1957, p. 147). Because both the cultural systems (religion, law, economy, art, science) and the external organization of society (family associations, common associations, church, state) “have emerged from the living context of the human soul, they can ultimately also be understood only from these” (p. 147). Only the understanding of the inner connection in us is able to guarantee the correct knowledge of these cultural systems and their outer organization because only the “uniformity and regularity in the soul life exists and makes an equal order for the many life units possible”: “Without the relation to the psychic context in which their relations are founded, the humanities are an aggregate, a bundle, but not a system” (p. 148).

7. Conclusions

By the end of the 19th century, there were two psychologies in Germany arguing over the proper method of studying the soul. One proceeded according to natural scientific methods, while others believed in hermeneutics as the art of understanding the inner soul. Both “schools” gave rise to their own ideas of educational research: experimental psychology to experimental education, from which empirical education was to emerge, and the humanities (Geisteswissenschaften) to humanistic education (geisteswissenschaftliche Pädagogik), which configured itself around the concept of Bildung, the idea of the aesthetic perfection of the inner soul (Tröhler 2016).

But no matter to which “paradigm” the researchers of the soul assigned themselves, they were always devout Protestants who often had Protestant pastors as fathers and/or had studied Protestant theology themselves. For example, the one who is considered the “father” of experimental education was Ernst Meumann, son of a Lutheran pastor, who earned himself a theological degree before going to study psychology with Wundt; a similar can be said of Meumann’s companion and competitor Wilhelm August Lay. On the other hand, the “oppositional” geisteswissenschaftliche Pädagogik was constituted in the context of German cultural Protestantism, which sought to harmonize and reconcile modern Western education, philosophy, and culture with Lutheran Christianity.10 In this “spirit,” one of the mandarins of humanistic education, Eduard Spranger, lamented the “inner corrosion” of Germany to an industrial state, social democracy, or even anarchy and promoted Fichte’s ideal of a “closed national Bildung” (Spranger [1902] 1973b, p. 201).11 Bildung was the expression of the—in principle, unmeasurable—inward perfection or “higher spiritual power” (Spranger [1920] 1973a, p. 267) which must guide an education research devoted to understanding (hermeneutics). “Man, who is a holy miracle to himself—how could he measure up to the methods of experimental psychology?” (Spranger [1922] 1969, p. 21). “Bildung,” as Spranger’s companion Herman Nohl, another mandarin of geisteswissenschaftliche Pädagogik, said a few years later, “is completed only where the creative progressive life is directed toward the future … in the totality of the soul” (Nohl 1933, p. 77).

On this basis, German education could not get away from Protestantism, no matter if it acted in a scientific–explanatory way or (in Germany, much more successfully) in an “inner-soul-understanding” way. It was built on the mystery of interiority, the soul, which one wanted to explore or understand in order to find redemption through the path of educational conception and intervention. It always remained stuck in the imagination of a relationship between the inner individual and a higher spiritual world—although mediated through the educator—which, in former times, had been related to the Christian God. Although explicitly theological arguments were avoided, because one wanted to see oneself detached from theology, the religious dimension of German education was never really discarded. Man is “essentially indefinable,” said, for instance, the third mandarin of geisteswissenschaftliche Pädagogik, Wilhelm Flitner, and thus man’s self is to be understood only “out of the love of God,” never as a theory, but as a “conception that takes place concretely in active, believing love” (Flitner [1950] 1983, pp. 139, 165).

Against this background, it is only consistent that the representatives of the understanding approach (the experimentalists were notoriously unhistorical) saw Luther as a decisive guarantor; he was seen as the “beginner of the new, by whose current we are still borne” (Spranger [1917] 1972, p. 15). Thus, in the “most modern sense,” Luther understood “faith” not as “freedom and autonomy,” but much more as “a willing surrender to the sanctifying grace of God,” whereby “faith … is wholly inward and gives the soul a world-surpassing power” (p. 18). Although they conceded that—in contrast to Erasmus—Luther had emphasized a contrast between science and faith, they also pointed out that it was precisely in Lutheranism that it had become possible to renew the spirit in the Reformation: “That is its educational significance” (Naumann 1933, p. 206). Luther, according to Naumann, taught people the eternal truth that they were fundamental sinners and that no “brooding over the ‘unknown God’” would help, but only the faithful, trusting acceptance of the “revealed God who has made himself known to the world in Jesus Christ,” and that only two principles would apply, namely God’s grace and “by faith alone” (p. 215).

Passages like these show how, mediated by psychology as the study of the soul, Germany’s modern educators still faced Luther’s dilemma. Since his anti-Catholic doctrines of justification of sola scriptura and sola fide, the necessity of the knowledge of the soul was simultaneously demanded and its impossibility testified. During this period, Lutheran Protestantism oscillated between the unknowability of the soul (sola fide in the broadest sense) and the imperative to grasp and improve the soul in order to attain salvation (or later perfection). Against this background, even the recurring tension between skepticism towards a (natural) scientific understanding of the soul and attempts to establish a scientific soul science to guide individual improvement can be understood as a feature of, rather than a contradiction in, the Protestant debates conducted under the label of psychology. Maybe it is precisely this inability to fully capture the soul accompanied by the (theological) obsession with it that explains the centuries-long dominance of Protestant thinkers in the history of psychology.