Modalities are usually defined as types of propositions with respect to their relations to existence. The three widely recognized modes are those of  actuality,  necessity, and possibility. The goal of this book is to historicize the category of modality and to show how the evolution of philosophical thought can be explained in terms of a transition from the "indicative" mode of pre-Kantian thought through the "imperative" modes of post-Kantian criticism and activism to a new, "third" epoch of postcritical thinking that is  defined with increasing frequency by the"subjunctive" modality and endows the varieties of "thinkables" and "possibles" with a higher cognitive and cultural value than ever before.

The introduction presents some of the more influential philosophical theories of the possible, including contemporary disputes on the nature of possible worlds (David Lewis, Nicholas Rescher, and others), and critical discussion of the "principle of plenitude," according to which all that is possible will become real in the infinite duration of time. The approach of this author is to argue that the "possible" is irreducible to any single mode of actualization.  Instead of defining the possible in traditional terms of realism,  nominalism, or conceptualism (which is the main target of contemporary discussions), the book builds the strategy of possibilism, which maintains the possible as a foundational category and applies it to various aspects of reality, language, and thought.

The first part of the book, "The Possible in Philosophy," explores the principal stages in the historical evolution of philosophy as a series of paradigmatic shifts in its prevailing modalities: the transition from the "indicative mood" in pre-Kantian thought, which claims to reflect reality as it is, to the "imperative mood" of post-Kantian thought, which acknowledges the gap between being and thinking. Accordingly, post-Kantian thought prescribes either critical limitations on thinking (logical positivism, phenomenology, analytical philosophy) or the transformation of being by force of social or individual action (Marxism, Nietzscheanism, existentialism). The culmination and exhaustion of these two extremes of the imperative modality, criticism and activism, can be observed in such late-20th century theoretical and historical events as French "deconstruction" and Soviet "perestroika" (literally "reconstruction"), the former demonstrating the dead-end of pure philosophical criticism and the latter of militant philosophical utopianism. Thinking thus moves toward a third, postcritical paradigm dominated by the modality of the possible.

Further discussion in this part of the book focuses on the status of hypotheses in humanistic knowledge, on the role of catharsis and conceptual persona in the creation of philosophical texts, and finally, on the problem of universals, treated from a possibilist perspective which challenges both the nominalistic and realistic solutions. Contrary to the famous principle of "Ockham's razor" ("entities should not be multiplied beyond necessity"), the  author sees the task of philosophy as the "multiplication of entities (or 'thinkables') according to possibility". Every word of ordinary language has the potential of becoming a philosophical term, and philosophy's specific goal is not to "explain" or "change" the existing world (these are goals of the sciences and ideologies, respectively), but to make it thinkable and to posit it as one of many possible worlds. The understanding of the inevitable discrepancy between the actuality of this world and the possibilistic character of philosophical concepts accounts for the intrinsically grotesque and self-parodic character of postcritical philosophical discourse.

The second part, "The Fate of Metaphysics: From Deconstruction to Possibilization," consists of two large sections. The first, "The Reverse Metaphysics: Critique and Deconstruction," addresses controversial issues and impasses  in the existing poststructuralist theory, in particular its implicit restoration of metaphysics on the level of signifiers while attempting to eliminate it, as a "metaphysics of presence," on the level of signifieds. A solution is sought in the interpretation of semiosis as the possibility of signification which establishes the status of signifieds as modally transcending the realm of signifiers, though not reduced to the dimension of actuality, or "presence." Many fundamental definitions in the theory of deconstruction, such as "the trace contains a possibility of meaning"  (Jacques Derrida), rely  on the concept of the possible without giving it any coherent interpretation. Deconstruction is the culmination of a critical epoch in Western thought and, potentially, an opening for a postcritical, possibilistic methodology which can be "developed" from deconstruction, as a positive from a negative.

The second section, "Construction and Possibilization," outlines the foundations of a new methodology in the humanities based on conceptual constructivism as a logical extension of the possibilist approach. Possibilization, as traced back to some ideas of Nicholas of Cusa and Schelling, demonstrates that alongside each concept, theory, or discipline there exists its "shadow," which, from a different perspective, could appear as a primary object of consciousness. Instead of focusing critically on the given discourse, possibilization  inscribes each concept  in a broader frame where it become only one in a whole family or cluster of co-possible concepts.  Central to this section is the discussion of the "interesting" as  a set of methodological criteria:  the least probable  assertions supported by the best possible arguments (combination of improbability and provabilty).  Possibilism transforms the deconstructionist critique of metaphysics into the creative construction of multiple "minor" metaphysic-s (in the plural).

The third part, "The Worlds of the Possible," deals with more specific applications of the philosophy of the possible to various fields of the humanities, such as cultural and social studies, psychology, ethics, and religion. The book shows how contemporary civilization has moved from the
paradigm of "the realization of possibilities" to a new one: "the possibilization of reality," which presupposes the excess of the possible over the actual, the proliferation of possibilities rather than their reduction to one mode of actuality.  Life in contemporary societies, based on such economic structures as "credit" and "insurance," stimulates the transformation of reality into a set of probabilities. Possibilist methodology is indispensable for historical studies. Contrary to the common opinion, that "history does not know the subjunctive mode," the outstanding German historian and father of sociology Max Weber has shown that the historian's ascription of meaning to historical events is only valid when alternative possibilities for these events are taken into account. This process of possibilization is further observed, for example, in the transition from ethics of categorical imperatives to "ethics in the subjunctive," formulated in terms of the unique possibilities of each individual rather than universal obligations. In theology, the introduction of possibilistic concepts suggests an alternative approach to the question of God's existence or non-existence and allows for a new interpretation of such categories of religious experience as "faith," "hope," and "love."

The Appendix "To Be Able, To Be, and To Know: A System of Modalities" offers a coherent description of  28 modal categories belonging to the classes of ontic, epistemic, and pure modalities (the  term "pure" refers to the modal concepts that are based solely on the "be able" predicate). All of them are  derived from the  definition of modalities as alternative uses  of the predicate "be able" (Russian "moch" embraces the meanings of both "may" and "can") in its  combinations with predicates "be" and "know." Thus the meaning of possible is described as "able to be"; impossible, "not able to be"; contingent, "able not to be"; necessary, "not able not to be."  Some intuitive concepts, such as "duty" and "miracle," "capacity" and "need," "desire" and "love," "faith" and "wisdom," "will" and "power," are logically elucidated by using modal predicates. Finally the book proposes a new philosophical discipline, potentiology, that would study "ableness" in its various modes, such as "will," "might," "possibility," "potency", "probability," "chance," "property," "faith," "play," "permission and prohibition," etc. Currently these modes are studied separately  in a number of unrelated disciplines, such as metaphysics, theology, mathematics, modal logic, law, political science, aesthetics, and others. Potentiology would become a major branch of philosophy along with ontology and epistemology, as the study of "ableness" or "potency" that cannot be reduced to the categories of being and knowledge.