Habermas is the preeminent European Enlightenment philosopher of late modernity. Unlike most contemporary thinkers, he has been an unrepentant defender of the Enlightenment. A whole lexicon is now entangled with his name: validity claims, reconstructive sciences, communicative action, all-affected, individuation through socialization, semantic contents with their latent moral and ethical norms that must and can still be rescued from the unfinished project of modernity—to name only a few keywords.

The focus of these two hefty volumes—the long dialogue between faith and knowledge—may seem anachronistic and the arc of the argument can perhaps be read as an apologia for “religion.” Furthermore, it may appear unusual to some who are familiar with Habermas's work, which has focused on contemporary social theory, democratic theory, and moral philosophy, as well as philosophy in general, because these two volumes articulate a distinct history of philosophy that takes us “behind” the Greeks to the Axial Age (i.e., 800–200 BCE).

We read in the foreword that Habermas had intended to use the title “On the Genealogy of Postmetaphysical Thinking: Also a History of Philosophy, Guided by the Discourse on Faith and Knowledge” (9). The editor did not like this, and thus Habermas settled for a more “laconic” one. But if we keep this title in mind, the systematic and theoretical intent of the work becomes, if not more evident, at least more legible. AGPh is the culmination of arguments that Habermas had unveiled in Postmetaphysical Thinking, Between Naturalism and Religion, and Postmetaphysical Thinking II.Footnote ¹

Against this overarching systematic intent I argue that we discern at least six subsidiary claims or goals of AGPh, which can be gathered if one is attentive to both the introduction and the epilogue, and Habermas's more recent “An Author's Retrospective View,” which provides a précis of his two volumes.Footnote ² These aims are:

1. 1. To reconstruct the “evolution” or “genealogy” of rationality out of the dialogue between faith and knowledge, which is not zero-sum.

2. 2. To challenge a distorting view of Enlightenment's rationalization of the lifeworld as a purification of religion. We have to rethink the Weberian picture of modernization as intrinsically linked to secularization. Habermas introduces a distinction between secularism as an ideology and secularization as a process.

3. 3. To challenge the caricatured relationship between religion and reason by offering sweeping genealogies of key concepts in Western thinking: freedom, deliberation, science, relationality, dignity, and rights, to name but a few. Ideas of “semantic contents” and “redemptive translation,” which have been staples of his approach to religion, become key for his genealogy.

4. 4. To exemplify and deepen our understanding of the “dialectics of secularization” as a process of rationalization and enlightenment. AGPh rewrites Horkheimer and Adorno's Dialectics of Enlightenment as a dialectic of postsecular enlightenment. If myth was already an exercise of reason, and reason reverts to myth in its reified form, then religion catalyzes reason, and reason turns into a religion, the religion of instrumental rationality. Both religion and reason are entangled in processes of secularization, which means that we have never been (thoroughly) secular, where consciousness of this “never been (thoroughly) secular” is what goes by the name of postsecular consciousness.

5. 5. To urge philosophers to take up the history of philosophy to reconstruct how arguments are made possible by surrounding background circumstances. Philosophy retains its independence from the natural sciences in part because it can and must engage in the writing of its own history as part of its advocacy of enlightened reason as a learning process.

6. 6. To stage the history of moral philosophy as the clash between Hume and Kant, that is, between the education of the moral imagination and affect on the one hand and the elucidation of moral sense—of the rational discernment of the moral point of view—on the other. This is a confrontation between emotivism (contextualism) and cognitivism (universalism).

At the center of these theoretical goals is the aforementioned temporal shift to the Axial Age. This shift has the salutary effect of “provincializing” the West through a genealogy of key concepts rooted in the Axial Age, which the so-called West shares with other world religions. In this sense AGPh is an exemplification of rooted cosmopolitanism. Habermas's temporal shift from the French Revolution, the Reformation, and the European Enlightenment—the cardinal points of reference in The Philosophical Discourse of Modernity Footnote ³—towards the Axial Age, places us in a pre-Eurocentric temporal stage. Given the centrality of this turn, I focus on what Karl Jaspers called the “cognitive gains” of the Axial Age in order to show what the new historical perspective of AGPh adds to Habermas's conceptualization of postmetaphysical thinking.

I summarize these gains in six steps, translating and synthesizing both Jaspers and Habermas. First, between 800 and 200 BCE, there emerged the critique of myth by logos, through the decoupling of religion from mythology. This is what we can call the “disenchantment of mythological world views.” Second, Axial Age religions began the “monothezisation” of God, a process that entailed the idea of a creator/sovereign God who is nonetheless separate from creation. This wholly other God is now articulated in conjunction with revelation in sacred texts. Just as God became an intractable and transcendent entity beyond being, this God began to be “domesticated” through “holy text.” Third, the wholly transcendent God, who is creator and sovereign, was also articulated as world judge, the enforcer of the divine law. Axial Age religions were religions of ethical refusals and the critique of existing social orders. Fourth, humanity was “spiritualized” as created creatures of the creator God. The other side of the idea of a transcendent monotheistic God is that of a dignified humanity. Fifth, philosophers, apostles, and holy men emerged as spiritual-ethical guides, critics of injustice, and advisers to kings or political leaders. The “moralization of the sacred” resulted in the idea of the moral exemplarization and education of “holy man.” Sixth, the Axial God, the keeper of the balance of justice that promises both salvation and judgment, is also the God that ruptures the cyclical conception of time, opening up the horizon of futurity. Human finitude is thus also revealed to be the temporal horizon of an unfinished history to come.

These cognitive gains orient and suffuse AGPh to configure a new “epistemic/linguistic” matrix in which religious claims are demystified and put into language in ways that are accessible to all. What Habermas previously called the “linguistification of the sacred” (162) now takes on a more concrete determination. Linguistification, by means of alphabetization, that is, the emergence of literacy through religion, and the grounding (imprisoning) of the sacred in holy texts, now became the means for both univeralization and individuation. This “epistemic/linguistic” matrix catalyzed a series of processes that led to the emergence of what Habermas calls postmetaphysical thinking, which is no longer dependent on religion. The Axial Age is thus crucial to understanding the relationship between postmetaphysics and postsecularism.

Axial Age religions were products of holy books; in fact, they became world religions because of their literary nature. This literacy further catalyzed the universalizing and individualizing dimensions of monotheism. Religious texts became the locus of both a struggle over God's transcendence and the role of the reader of the holy text as a text to be interpreted and transmitted. Second, because the encounter of the sacred is now meditated by a “text,” Axial Age religions are self-disenchanting and self-secularizing. The more the sacred is mediated by a text, the more dissensus is produced: which sacred texts, which interpretation, which interpreter, which interpretation. This dual process of self-disenchantment and self-secularization of literary Axial Age religions turns into a process of rationalization and critique of the metaphysical and transcendent. Axial religions are postmetaphysical because they are alphabetic, literary, and thus hermeneutic-grammatical religions.

The ideas developed in Postmetaphysical Thinking Footnote ⁴ orient AGPh and remain indispensable to making sense of these two volumes. In this collection of essays Habermas identifies metaphysics with four key characteristics, which he summarizes with three subheadings: identity thinking, the doctrine of ideas (i.e., idealism), and a strong concept of theory, all of which are unified in the philosophy of consciousness (above all in German Idealism).Footnote ⁵ Historical developments have problematized these basic assumptions. The transformation of the sciences and their concomitant success in terms of technological applications challenged the primacy of philosophy with the profiling of “procedural rationality,” which dispenses with ontological and metaphysical commitments. This led to the “detranscendentalization” of all received ideas from metaphysics (ideas and ideality were historicized). The criticism of “reification and functionalization of forms of life and interaction”Footnote ⁶ spread out through the nineteenth century, and philosophy itself became the object of such criticism. Finally, the success of the human and natural sciences, now oriented by a procedural rationality aimed at empirical efficacy, led to the demotion of the primacy of theory over practice.

Habermas argues that “postmetaphysical” thinking dissolves the autarkic conception of the epistemic subject into linguistically constituted intersubjectivity, and thus leads to the “deflation of the extraordinary.”Footnote ⁷ However, it retains two key themes of metaphysical thinking. First, it still aims at a holistic view that brings together the one and the many, the whole and its parts, through the linguistification of reason. Linguistically achieved understanding, which is from the outset intersubjectively generated, is the porous unity of assent and dissent, which presupposes differences among speakers.Footnote ⁸ Every speech act by every communicative actor is the intersection point of embodied particularity and transcending universality.

The second theme that is retained, albeit in a highly sublimated fashion, is the primacy of the reflective over the active life. Habermas traces the strong concept of theory to the privilege accorded by world religions to salvation through contemplation. The individual pursuit of salvation (release from worldly suffering) was sublated by the philosophy of consciousness into a pursuit of theoretical reflection that is absolute and self-justifying.Footnote ⁹ With the linguistification of reason, and the consequent rendering of subjectivity as thoroughly intersubjective, self-positing, and self-justifying, subjectivity becomes a self-accounting and truthful (authentic) subjectivity that has to account for itself to others in order to account for itself. Every speech act in which we use the illocutionary “I” is also a claim that this “I” be recognized “as an individual person who cannot be replaced in taking responsibility for my own life history.”Footnote ¹⁰

Habermas concludes “Themes in Postmetaphysical Thinking” by stating that “philosophy, even in its postmetaphysical form, will be able neither to replace nor to repress religion as along as religious language is the bearer of semantic content that is inspiring and even indispensable, for this content eludes (for the time being?) the explanatory force of philosophical language and continues to resist translation into reasoning discourses.”Footnote ¹¹ Keeping this conclusion in mind, it is possible to read AGPh as a long, expansive, and detailed demonstration of how Western philosophy (and those non-Western traditions that flow from the Axial Age) has continued to be nourished by its millennial dialogue with revelation, faith, religion, and theology. Axial Age religions, insofar as they are self-secularizing, at the same time unleashed the processes that led to the postsecular. Postmetaphysical thinking and postsecular consciousness are thus two sides of the dialectics of secularization.

AGPh, however, is more than a long footnote to Postmetaphysical Thinking; it also exemplifies and advances the claim that the gains of all forms of enlightenment are the result of a learning process mediated by the millennial dialogue between “faith” and “reason.” Habermas traces this in detail, offering brilliant insights about thinkers well known, neglected, and now forgotten. In his telling, this learning process is not unique to Europe, but is shared by all the world religions that emerged out of the Axial Age. To paraphrase Habermas, the genealogy of both postmetaphysical thinking and the postsecular condition has a cosmopolitan intent.