Jaspers has emphazised that the philosophy of consciousness adopts a "contemplative" meaning on Edmund Husserl's phenomenology. He raises the same objection to Husserl as he does to Descartes for they both attempt to validate the mathematics-based criteria of evidence and certainty for philosophy. Departing from his clinical expertise as a psychiatrist, Jaspers confronted the "deviations" of the pathologic psyche with the claims of coherence and meaning made by the phenomenology of consciousness, given that the pursuit of truth in itself does not address a proper understanding of an ill consciousness due to the foundation of philosophy as a "rigorous science."
Since the scope of the phenomenology of consciousness as a method is restricted to describing particular phenomena, Jaspers decided to widen its scope and to use it to also describe the experiences of mentally ill people. He considers this latter only a subordinated method for providing descriptions, and therefore as a method that is mainly suited for scientific research. Thus, even though he accepts it under no circumstances as a philosophical method, phenomenology allows him nevertheless to objectively represent phenomena of mental life, but it neither opens the possibility for self-transformation of the self, nor contributes to the unfolding of the "inner action" of the transcending thinking—which according to Jaspers is a necessary condition for philosophizing. Transcending thinking is the place to which existential clarification belongs as the inclusive philosophical realm of boundary situations, and the place where the turning in Jaspers' philosophy occurs regarding to Husserl's phenomenology. "Actually," Jaspers states,
there exists a radical difference between the phenomenology of consciousness and the illumination of Existenz...it is described...as the leap from observing to philosophizing, that is, from knowing something to inner action through thinking. [RC 819]
This method does not mean reaching some understanding (Verstehen) of the ill psyche; that is to say, an interpretation of the connections that exist between mental states and the relationships and motivations that encourage them (PA 18). For Jaspers, who first introduced phenomenology into psychiatry, this only constitutes an empirical method for defining and distinguishing mental states.
Although since his Cartesian Meditations (1931) Husserl had shown his interest in the world of human beings— as a field of transcendental intersubjectivity and an opening of space to the lifeworld (Lebenswelt)—it could be said, when seen from the position of Jaspers, that tensions were arising from the boundary situations between consciousness and Existenz as they remain marginalized in Husserl's phenomenology. This is because the boundary situations break the flow of the self-reflective consciousness. If we follow Jaspers, then it is difficult not to take into consideration that the inherent limit of phenomenology as a philosophy of consciousness makes it impossible to move towards the philosophy of existence, since the latter must be inclusive with regard to all human potentialities. Jaspers' relationship with Husserl's phenomenology takes into account two basic circumstances: first, Existenz goes beyond consciousness (and also comprehends it), however phenomenology stays within the scope of the latter; second, Jaspers' philosophy calls for an ethical dimension of philosophizing leading thought to practical life—wherein the contemplative dimension of reflexivity is exceeded by the torn condition of the existent.
Drawing on Kant's transcendental method in so far as it aims to transcend what is objective (RC 792), Jaspers recognizes in this method the specific characteristic of the philosophical method which is distinct from the scientific method. Jaspers believes Kant reveals the way to Existenz, as it is open to self-reflection by the acknowledgment of: (1) the philosophical orientation toward the world without falling prey to deceptive illusions, as the way of science and knowledge of what is objective and as a basic condition of philosophizing; (2) the way of thinking which transforms the world into freedom and showing thereby that the world cannot be closed in on itself—being also incomprehensible as a whole for objective knowledge. Additionally, Jaspers states that the effort to transcend the subject-object split runs through science and objective knowledge. Kant keeps a similar stance regarding the relationship between science and philosophy, and he points out in Kant the idea of the world via antinomies and fallacies as a result of identifying it with a wholeness that incorrectly claims to exhaust the being of the world in its objectivity. For him, Kant would have taken a decisive step towards the possibility of the philosophy of existence, by providing the methodical foundation for the
idea of the phenomenality in correspondence with our existence within the subject-object duality, the latter as subordinated as forms of intuition to space and time as forms of intuition, and to categories as considered as forms of thinking.
Yet, while he defines the scope of the subject as incommensurable with the object's objectivity—which is rather set according to this scope as its necessary reference—Kant conceives the subject, at the same time, according to an universal human condition by addressing the structures of reason for all possible rational subjects. But the subject, conceived like this, stands in contrast with the singularity and uniqueness of the individual historicity, which decides and acts within the scope of possibilities as they are conditioned according to the occurrence of boundary situations. However, Jaspers follows Kant and emphasizes that it is impossible to think, unless that which is thought is objectified—and he also states that all the objectifications must be methodically canceled by the ceaseless transcending-thinking via contradictions and circular argumentations, expressing the elusiveness of what transcends the framework of the subject-object split, and leading thought to the limits of the thinkable. But in this case, according to Jaspers, these are limits (boundaries) as they are given within thought. Yet boundary situations cannot be the object of neither knowledge nor logical reasoning, but rather they only drive the existential clarification.
In a similar way, one can say that while Kant's transcendental philosophy has adopted as a starting point the experience of knowledge's fulfillment according to the modern scientific reason—and it also critically examines the conditions for this possibility—Jaspers' criticism begins with the de-realization, so to speak, of the empirical existence (Dasein) in a world in which the distinctive feature is the crisis. And it also examines the potential conditions of Existenz through the praxis, as they are unfolded by the existential clarification and communication. For Jaspers, the order of the Existenz cannot be found in any other than that of the very Existenz and it has an indirect meaning only, for the being of Existenz is mere possibility. When transcending-thinking "thinks about objects through non-objective ways; jumps over our own shadow by thought; thinks by methods using understanding and going beyond understanding" (RC 794), it performs the "basic philosophical operation" and makes it possible to change the attitude of consciousness, i.e., its conversion. Jaspers considers thinking's conversion as a part of the formal transcending, or what amounts to the same thing, it is in accordance with the "order of reason." But simultaneously he also thinks this conversion responds to the reality and the meaning of historicity, what Kant did not understand—so, following Jaspers, is that he had lost sight of the ethics of responsibility, with the aid of which Max Weber later develops his thinking later. Then, Jaspers stresses:
What, from the point of view of a philosophy of history, he [Kant] permits is merely the attempt to write a history in which it is shown in how far and in how far not -measured by the ideal of reason- the events and transformations which occurred were advantageous, and how all this is connected. [RC 755]
The dialectic of historicity (as an existential condition according to Jaspers) manifests itself in the objective history of the empirical existence (Dasein), it allows to identify any historic situation of what is empirically given as a boundary, and also creates the conditions for any historic existential possibility. "In any case," Jaspers points out,
what happens depends on man. There is nothing that might be considered as unavoidable, as fateful....Within us is what gets to be, and within every individual, definitely, although no individual can decide where it goes history's guidance.
With regard to the human experience of boundary situations, it appears that the heterogeneity of the individual historicity is irreducible to the Kantian universal subject, not only due to its historical empirical manifestations, but also due to its existential potentiality.
For Jaspers, boundary situations (Grenzsituationen) do not constitute themselves a content of thought, but rather are the expression of the discontinuity and of the boundaries of the potential Existenz. If the factual situation defines the empirical existence (Dasein), the boundary situation defines the Existenz: According to Jaspers, to exist and to experience boundary situations "are the same thing," and "the authentic function of the boundary" (F2 67-8) is to point out the Transcendence, while remaining immanent. Boundary situations have a historical (geschichtliche) characteristic for the potential Existenz and this is unique for the individual, although one cannot modify or suppress it, but can clarify it by way of active participation in it. The task of philosophy consists in the clarification of the Existenz according to the existential physiognomy of the individual, to the extent that it can open up and encourage the possibility of (self-) reflection within boundary situations and by making it possible to establish its scope. Death, guilt, struggle, suffering, and foundering as boundary situations express the finitude of the Existenz and, at the same time, its potentiality. Their meaning can only be communicated in a paradoxical way, as opposed to the empirical existence—to which the Existenz, however, has to hold onto, given that this is its only means to manifest itself.
In Jaspers' view, the meaning of Kant's transcendental method has changed through the clarification by the Existenz, yet it remains an essential condition for this clarification. Following Jaspers, Kant's transcendental philosophy is at the centre of the question regarding the possibility by proposing the well-known, three metaphysical questions, related to knowing, doing, and believing. Departing from them, Jaspers' philosophy founded the method of transcending as transcendental possibility, whereby transcending does not allow to grasp any being, "but clarifies one feature of our empirical existence, in general" (F2 408). Further, his conception concerning the existential clarification contributes to the expansion of the transcendental method because it takes into account not only the realm of transcending into thinking—where Transcendence can be represented as an Idea—but also, at the same time, it refers to the transcending in the sense of an existential potentiality, just there where thought no longer transcends; that is, in the boundary situations. It is in this sense that the notion of boundary situations in Jaspers' philosophy represents a turning point directed towards the realm of Existenz regarding the philosophy of Kant, and the criteria that opens up a new scope for philosophical reflection.
It is not only apparent for the transcending thinking through the existential clarification that thought is at stake in boundary situations, but also that the Existenz puts at the same time at stake its potentiality and its fate. Self-reflection gives way, within the existential clarification, to the acceptance of or acquiescence to the judgments (affirmative or negative), and to resolutions through action. Jaspers stresses that the time of resolution always involves with regard to the Existenz the possibility of risk; in this way, from the point of view of the existential clarification, the scope of any rational ethics would be objectionable, if it is considered as a sufficient warranty for the right course of action—in any case, it can only support the restricted possibility for the prudent action, "since Existenz must decide on time and it cannot, arbitrarily and without interruption, check for the sake of prudence", says Jaspers, as "time compels":
Existenz cannot wait...it must decide instantly each time, then it should run what only after an endless cognition would be clear and apparent, at the end of time...Existenz has to risk itself. And yet at the decision, at resoluteness, it stays on expectation of whichever comes. [FFR 407]
From the perspective of the temporality and historicity of the Existenz, Jaspers questions the Kantian claim, "do not risk anything, because of the material safety, to the possibility of being unfair" (FFR 407). This claim seems to be contradictory to the temporary condition of the human being, in which what is decided in a single instant is decided for eternity. Jaspers remarks, the Existenz knows that when acting, it might be unfair; or it may also fails to do the required action when it remains unmoved, regardless whether it by some event gets involved either directly or indirectly. From this could be inferred that, for Jaspers, the Existenz is not able to avoid its guilty condition via some rational ethics.
Boundary situations draw the unique outlines for the Existenz together with the transcending thinking, and this latter moves in circles; it seeks to break the siege by objectivities and boundaries; it is directed towards non-objectiveness, and it creates room for the potential Existenz. Jaspers goes further regarding the transcendental method, because clarification of Existenz is the goal for the transcending-thinking, which opens the possibility for the subject to become itself. And this constitutes "the ages-old secret of self-consciousness" (RC 799). So the "method of transcending" does not only have a critical meaning for Jaspers' philosophy, but it also has an existential aim: "The general transcending, which is philosophically communicated, does not match with the existential transcending to oneself, and while it is true that philosophical thinking awakes it or corroborates it, this is not, in turn, carried out by it" (F1 55). In this way, philosophy cannot offer the protection needed in order to avoid every risk for the existential transcending.
Kant's method offers Jaspers a key to addressing the potential Existenz toward the performing role which corresponds to it; that is, to put at stake its potentiality; in such a case, a new attitude is required for the consciousness in the shape of a conversion or "re-birth of thinking" (RC 794) by appealing to the existential communication and clarification. The "basic philosophical operation" is carried out as a leap to a new level of thinking; and it is reached when, at the same time, the self-transformation for the subject who thinks is reached by so doing. The conversion of the way of thinking from intellectual thinking to comprehensive reason—not only in the realm of theory, but also by way of its implications for practical action—is not a spontaneous process but rather, it transcends mere reflection via a willful decision, involving it in communicative participation. For Jaspers, the clarifying-thinking is an answer to a call from an ethical dimension, which is inherent in the unavoidable risk of existential realization.
Jaspers has exposed reason to all the risks of the Existenz. The existential clarification has been conceived by him not as an overcoming, but as an expression of the discontinuities, paradoxes, and boundaries, by which the problematic path of communicative and comprehensive reason unfolds. The encounter of the reason with the Existenz is never final, nor does it lead towards some sort of reconciliation in an impossible identity. Reason does not purport, as a retrospective view, to deliver judgment on the Existenz: Unlike Minerva's owl, it does not lift its wings at the nightfall. In an endless approximation, reason shows those polar conditions, without which the human condition cannot be realized. The existential clarification does not attempt to declare a theory of the being of the Existenz, but rather a criticism on human experiences—leading to the encounter with the Transzendenz.
Since only the self can execute this process, the basic philosophical operation always has an individual character, yet it is only achievable by means of communication. So, the conversion of consciousness has an inherent social dimension, which is linked to the historic conditions of the boundary situations, and also to the shared experiences of communities. And as Jaspers has pointed out, the change in attitude of the consciousness—which is generated by the potential Existenz while facing risks undergoing attempts to reach its realization—represents not only the entrance to the freedom of philosophizing, but it also lays bare the possibility for the failure on par with the unfettered conversion of thinking and existing.