“Two modes of understanding dominate the history of ideas. One posits the overarching unity of knowledge, the other cherishes its multifarious diversity. Unity is the goal of those who seek a single all-encompassing explanation of everything. Diversity is lauded by those who commend difference and variety as life-enhancing” (p. 1).
This is the underlying idea through which David Lowenthal explores major themes of pressing social and environmental relevance in Western thinking in his Quest for the Unity of the Knowledge, his last work published before his death in 2018. Is unifying knowledge achievable? Is it desirable? Answering these questions had been the central theme in the divide between the “Two Cultures,” namely the natural sciences and humanities. The natural sciences model the world through the language of mathematics, of “objectiveness” and logical coherence, seeking an ultimate answer or “theory of everything” that could explain worldly phenomena. The humanities, in contrast, emphasize the role of subjective experience, promoting multi-layered explanations of reality, and criticizing what many see as a disenchantment and soullessness that science has brought upon the natural world.
In the first chapter, Lowenthal recounts the history of this cultural division from the Huxley–Arnold (science vs. literature) conflict to the Einstein–Bergson (physics vs. philosophy) debate and C. P. Snow´s 1959 work Two Cultures and the Scientific Revolution. The divide between these opposing cultures, he claims, became magnified through features such as linguistic specialization, methodological diversity, and funding allocation, making trans- and cross-disciplinarity hard, if not impossible, to achieve.
This cultural dualism between the natural sciences and the humanities is but one among many “dualities” shaped by the Western tradition throughout the course of its history. Most relevant in terms of the recent environmental and social challenges posed by anthropogenic activities, suggests Lowenthal, is the dualism between humans and nature, which he engages with in the second chapter. This dualism is manifested through Christianity in its multifaceted views of nature, and through the role of science in investigating “nature” and circumscribing it as a discrete object of specialized knowledge. Christianity simultaneously unifies the cosmos by placing humankind at its center and separating God from materiality, eternal from ephemeral, sacred from sinful. Science attempts to explain nature and humanity by means of a unifying model, while also compartmentalizing knowledge. In both stances, as also argued in Lynn White´s famous The Historical Roots of Our Ecologic Crisis, the Western view of nature was the same: a pool of resources for humankind to exploit, a force to master and subdue. Can the gap between religious spirituality and scientific rationality be bridged in order to develop a positive and proactive philosophy of nature? Yes, perhaps. As Lowenthal argues, “that human action profoundly alters the physical fundament is the most momentous insight serving alike to sunder and to bridge the two realms.” (p. 55)
An interesting account of how to bridge these two realms is given in the third chapter. Here Lowenthal discusses islanders, who have historically been perceived as culturally and socially backwards compared to “civilized” and technologically advanced mainlanders. Contrary to these stereotyped visions, the intimate relationship they build with their environment enables islanders to develop the strong social unity needed to cope with threats such as harsh climate or natural calamities. The very ecology of islands equips them with a recognition of the limits, unsustainability, and possibly ecological danger of economic growth. In this sense, islanders are experienced unifiers of knowledge.
Central to the divide between the unity and diversity of knowledge is the pure/hybrid dualism that Lowenthal discusses in the fourth chapter. Purists, he argues, are not unifiers: they do not advocate the unification of models of thinking, but rather their inherent incompatibility. Purity served elites as it conferred social privilege, and provided a justification for unequal land ownership and social hierarchies. Even science was later employed to advocate for purity, as was the case in taxonomy, which amplified hierarchical stereotypes, and physiognomy, which amplified racism. Blood itself had been a symbol of social status and the preservation of its purity was meticulously sought during the middle ages. On the other hand, those embracing hybridity pursue unification through diversity. Contemporary ethics largely favor hybridity—for example, by welcoming immigrants or supporting inter-ethnic marriage—based on a fundamental principle of unity among humans as well as living creatures. This is obviously a focal point of environmental humanities research, yet it is not free from problems in its goal for unification. Indeed, in ecology the distinction between native and invasive species is regularly adopted, while favoring “natural” products over genetically modified has become a common practice in Western societies; both cases representing a way in which the ideology of purity persists.
In his fifth chapter, Lowenthal discusses another crucial dualism within social, political, and environmental debates, namely between global stewardship and heritage on the one hand, and tribalistic and nationalistic interests on the other. What is widely cherished as a collective good, especially by international agencies like UNESCO—perhaps as a remnant of a lost past belonging to humanity as a collective enterprise—is often turned into an instrument of contention, scorn, or discrimination, or even used to claim superiority. To ensure social cohesion and solidarity, humans crafted exceptionalist narratives of their origins, history, and culture, thus shaping a heritage that, like language, is necessarily alien and alienates outsiders. The environment plays a particular role in heritage, for it constitutes a legacy that is both local and global, and necessitates global stewardship efforts.
In the sixth and final chapter of the book, Lowenthal assesses the role of history and the ways it is used instrumentally in the present. Past and present are investigated as a dualism defined, on the one hand, by those who hold to a bygone vision of the past against the decay of the present (nostalgic), and those who see nothing but the present itself, absorbing the past into a perpetual “now” (amnesiacs).
Lowenthal believes it is crucial to “cherish both unity of knowledge and diversity of insight” (p. 196). According to him, neither of the two endeavors—of unifying knowledge or diversifying it—is absolutely good or bad, epistemologically better or worse. Rather, there is a creative tension that arises between these conflicting stances, a tension that must be kept alive for research to progress, or even to exist. The “dualism” he investigated throughout his book represents a major forma mentis that has existed in Western thinking since at least classical philosophy.
The book does not probe deeply into the extremely complex origins and impact of perhaps the most archetypical dualisms in Western, or even human history—life/death, day/night, up/down, pleasure/pain, good/bad, etc. Furthermore, Lowenthal does not explore the logical and epistemological issues behind the very definition of knowledge, and the project of unifying it. The book is thus a discussion of selected (nevertheless interesting) dualisms rather than a genealogy or philosophy of dualism and unity as methodological and ontological stances. Although this is most likely the aim of the book, the lack of an “archeology”—to borrow a Foucauldian term–of “unity” and “hybridity” as methodological and ontological categories is sometimes evident. The idea of unity, for instance, was a central theme in much of Plato´s philosophy of the Good. This was later revised by the Neoplatonists, which deeply influenced early Christian theologists and philosophers, and consequently the development and theological success of modern Christianity over other cults and religions (Manicheism, for example). This could provide one of many explanations behind the simple, yet important question that arises spontaneously from the book, but that Lowenthal does not address directly: why do we think in terms of unity or hybridity?
Nonetheless, the author offers a critical and historical account, accessible to scholars and non-academics alike, of specific contemporary dualisms that impinge on active and proactive stances towards a more inclusive, more ethical, and more environmentally aware society.