1. Husserl’s phenomenology as a subjective science of the ultimate epistemological principles

For Husserl, the most fundamental epistemological question is how subjectivity can be the source of objective knowledge (cf. Melle in Husserl Reference Husserl1984, xxxi). Transcendental phenomenology is supposed to provide the solution to this problem. It is a subjective science in the sense that it employs a descriptive (but also eidetic) methodology. One of its core convictions is that subjective acts are the ultimate source of all justification. In addition, Husserl’s phenomenology is intended to be ultimately elucidating and ultimately elucidated.Footnote ¹ In this sense, Husserl understands phenomenology as the “First Philosophy,” the “science of the principles, namely science of ultimate elucidation, of ultimate justification and sense-bestowing ” (Husserl Reference Husserl1984, 165).Footnote ² This remains true for Husserl for the rest of his career although it is not always as clearly stated as in his Londoner Vorträge (1922):

This brings us to the question of whether phenomenology can be both a subjective science and the science of the ultimate epistemological principles. For Husserl, a science of the ultimate principles must be a subjective science. This is because in order to elucidate the ultimate epistemological principles you must show that one is justified in believing these principles. Justification, however, is gained through subjective acts: “All knowledge is realized as subjective act, and the subjective act must harbor within it what pleads and warrants its claim to legitimacy. Only in this is <the justification> to be sought” (Husserl Reference Husserl2008, 129).

This crucial passage tells us two things: Firstly, subjective acts are the carriers of justification. Secondly, it is internal factors that give justification-conferring acts their justificatory force. The first point is the reason why phenomenology as a First Philosophy must be a study of consciousness. Since transcendental phenomenology has the ambition to elucidate the ultimate epistemological principles, phenomenology has to investigate the carriers of justification, i.e., mental states. In the next section, we shall see that, for Husserl, originary presentive intuitions are the ultimate source of justification. The second point indicates why phenomenology has to be descriptive and eidetic. Only some mental states have justificatory force. What distinguishes justification-conferring mental states from non-justification-conferring ones are internal factors. There are “immanent qualities that […] constitute the mark of true legitimacy” (Husserl Reference Husserl2008, 132). Thus, Husserl is an internalist with respect to epistemic justification. Not “objective” external factors, such as truth or reliability, make experiences justifiers but factors internal to these acts. In fact, Husserl holds that it is the phenomenal character of originary givenness that gives justification-conferring experiences their justificatory force (cf. Husserl Reference Husserl2008, 342–43; Reference Husserl1982, 36).

Acts that exhibit originary givenness (i.e., originary presentive intuitions) are experiences in which the object/content is given in a presentive manner. These acts are contrasted with empty, signitive acts in which what is given to us is not the object in its actual presence but the object as something that is meant only (cf. especially Husserl’s Sixth Logical Investigation). The prime example of originary presentive intuitions are perceptual acts in which we are perceptually aware of the object in question. If you believe that there is a table in the room next to you, this belief is a signitive act. If you go and check and see the table, this perceptual experience is an originary presentive act. For Husserl, originary givenness and evidence are intimately related. In fact, it is the character of originary givenness that discloses the nature of evidence (for more details on Husserl’s conception of evidence, cf. Berghofer Reference Berghofer2019). “Evidenz is nothing but a word for the quality of givenness. […] Evidenz is a word for the fact that […] there is a difference between acts that not only think that something is thus and thus, but are fully certain and aware, in the manner of perspicacious seeing, of this being and being thus” (Husserl Reference Husserl2008, 153). It is to be noted that “originary givenness” is understood in a remarkably broad sense. Not only perceptual experiences of physical objects but also introspective intuitions of one’s own mental states and eidetic (a priori) intuitions of, e.g., logical and mathematical truths are originary presentive intuitions.Footnote ³ For our purpose, it is particularly significant to emphasize that also a priori intuitions of epistemological principles count as originary presentive intuitions. Importantly, “originary givenness” denotes the way an experience presents its object, which means that it characterizes the distinctive phenomenal character of an experience.Footnote ⁴

Husserl clarifies that this phenomenal character, this form of givenness or way of an experience presenting its objects/contents, is not an external factor but an “internal, purely descriptive (or phenomenological) character” (Reference Husserl2001a, 83). In current debates, the phenomenal character of an experience is introduced as “what it is like subjectively to undergo the experience” (Tye Reference Tye and Zalta2015, sec. 1).Footnote ⁵ Importantly, an experience’s phenomenal character cannot be studied “objectively” with the methods of the natural sciences but only from the first-person perspective, in a descriptive fashion.Footnote ⁶ Thus, phenomenology must be a descriptive science. The aim, however, is to gain a priori truths about essential characteristics of different forms of originary givenness and how they relate to different forms of evidence. Hence, the descriptive methodology of Husserlian phenomenology must be supplemented by an eidetic methodology.

For Husserl, and this is a central thought that plays a crucial role in all his major works and is presumably developed in most detail in his Crisis, for any natural science subjectivity is the ultimate source of justification (cf. Husserl Reference Husserl1984, 120). “Subjective acts motivate everything” (121). This, of course, does not mean that phenomenology can provide the laws of physics or chemistry, but the justification of any law of physics or chemistry, ultimately, depends on originary presentive acts such as visual experiences and it is the task of phenomenology to elucidate why visual experiences have justificatory force and how laws of nature can gain their justification from such experiences.

Importantly, subjectivity is not only the source of justification for the natural sciences but also for the formal sciences such as mathematics. Mathematical statements are justified by apodictic insights (Husserl Reference Husserl1984, 121–22) and for Husserl there is no doubt that “apodictic evidence justifies” (Husserl Reference Husserl1984, 122).Footnote ⁷ Like visual experiences, however, apodictic intuitions are subjective experiences that gain their justificatory force from something internal (namely their originary presentive character). “Apodictic Evidenz, the consciousness of necessity, seen, actually experienced (and not just spurious and presumed) is, though, something subjective, a singular experience, and in it lie grounds for justification” (Husserl Reference Husserl2008, 120). Thus, contrary to what might be suggested in the Prolegomena, it is not a formal discipline, such as formal logic, whose task it is to elucidate the ultimate sources and principles of justification, but the task of noetics, i.e., the phenomenology of reason that is basically the study of subjective acts and modes of givenness.

It is to be noted that in this transcendental phase, apodictic insights and formal logic themselves are in need of epistemic elucidation. In the Prolegomena, Husserl pointed out that we need to accept apodictic insights because doing otherwise leads to unacceptable consequences such as relativism and skepticism (cf. Prolegomena, ch. 7). This is still true for Husserl, but now the question is a different one. The question is not, why should we believe that apodictic evidence is a source of justification? The question rather is why is apodictic evidence a source of justification? What gives it its justificatory force? Although related, these are two different questions, and Husserl realized that the latter is more fundamental.

Here we can see the main difference between Husserl’s formal and his mature transcendental logic. Formal logic is a general theory of science that abstracts from the individual sciences and aims at extracting the first principles and axioms such as the law of contradiction and the excluded middle. Based on these axioms, in further consequence, it aims at building purely logical theories (Husserl Reference Husserl1984, 124). A transcendental logic, on the other hand, is a descriptive and eidetic study of consciousness, subjective acts, and modes of givenness such that it can

Again, we are confronted with Husserl’s aim of introducing transcendental phenomenology as “the ultimate elucidating science.” Perhaps one of the most concise and ambitious outlines of the project of transcendental phenomenology can be found when Husserl delivers the following synopsis and prospect of a phenomenological theory of reason (noetics):

Citing this passage, Iso Kern states that “this noetics in correlation with ontology is for Husserl nothing but transcendental phenomenology” (Kern Reference Kern1962, 334). Here I am in full agreement with Kern. This passage perfectly illustrates what a Husserlian transcendental phenomenology is all about.

Having said this, it should be noted that this passage can easily be misinterpreted as a claim to omniscience and infallibility. According to my understanding, a phenomenological epistemology does not aim at ensuring that we know everything or that all our justification is infallible in the sense that none of our beliefs, such as that there is a table in front of me, could turn out to be illusory. Instead, the aim of a phenomenological epistemology is ultimate elucidation (Letztaufklärung) in the sense of unfolding the ultimate sources of justification. The question is not whether my belief that there is a table is infallible (it is not). The question is whether my belief is justified, and, if so, which acts are responsible for justifying it and what it is that gives these acts their justificatory force. And most importantly: what are the fundamental epistemological principles that ultimately elucidate and are themselves ultimately elucidated?

2. The ultimate epistemological principle and ultimate elucidation

This section is supposed to answer two fundamental questions:

1. Q1: What are the ultimate epistemological principles?

2. Q2: What does it mean for a principle to be ultimately elucidating and ultimately elucidated, and how could one principle be both?

For Husserl, it is clear that the ultimate principles must be epistemological principles that are a priori eidetic laws (Husserl Reference Husserl1984, 235–36). Husserl used a rather unambiguous terminology in order to point out that there is one principle that is more fundamental than all the others. This is his principle of all principles:

Similar ideas are expressed in First Philosophy II, in which Husserl introduces his “most general principle of justification” (Husserl Reference Husserl1959, 32) and in the Cartesian Meditations, when he establishes his “first methodological principle” (Husserl Reference Husserl1960, 13).Footnote ⁸ Let us put the basic idea of the principle of all principles as follows:

Despite its conspicuous and promising name, PaP does not play the prominent role in the Ideas that one might expect and following its introduction it is hardly ever mentioned again. I believe that Husserl underestimated its full potential, and, in this section, we shall see what role it can play in the project of ultimate elucidation.

To unfold its full force, PaP must be paired with the Husserlian idea that ultimately all justification depends on originary presentive intuitions, i.e., that originary presentive intuitions are not only a source of immediate justification but also the ultimate source of justification. In Ideas I, this is expressed as follows:

From the context it is clear that “immediate ‘seeing’” is synonymous with originary presentive intuition. Based on this passage, we can introduce the principle of ultimate justification (PUJ):

Combining PaP and PUJ amounts to what I shall call the ultimate epistemological principle (UEP):

In this section, we shall see that UEP can be rightfully called ultimately elucidating (letztaufklärend) and (by virtue of PaP) ultimately elucidated (letztaufgeklärt). Thus, UEP is ultimately elucidating and ultimately elucidated.

In what sense can UEP be considered ultimately elucidating? Think about an arbitrary claim of physics that is more or less empirically justified by induction or inference to the best explanation. In such a case, the chain of justification can be traced back to simple observations, i.e., perceptual experiences.Footnote ⁹ Physics is in no position to elucidate why perceptual experiences are justifiers. Importantly, physicists do not need to elucidate why perceptual experiences are a source of immediate justification. Since perceptual experiences are a source of immediate justification (perceptual experiences are originary presentive acts), physicists are justified in trusting their perceptual experiences. Of course, one can pose the questions: Why are perceptual experiences justifiers? What gives them their justificatory force? These are reasonable questions which could only be answered unreasonably by empirical methods. They are questions for a First Philosophy—an ultimate science that elucidates the ultimate epistemological principles. The answer, of course, is PaP. Since every originary presentive intuition is a source of immediate justification and since perceptual experiences are originary presentive intuitions, perceptual experiences are a source of immediate justification. In this sense, UEP is ultimately elucidating. It elucidates the ultimate sources of justification by revealing the only Footnote ¹⁰ sources of immediate justification (i.e., originary presentive intuitions).

Note that the physics example works analogously for mathematical insights. Without immediately justifying a priori mathematical insights, such as that 1 is smaller than 2, no mathematical theorem could be justifiably believed. This is also true for theorems that cannot be grasped immediately but are deductively inferred. The mathematician does not need to know why such mathematical intuitions are a source of immediate justification, but every step of her proof must be accompanied by such intuitionsFootnote ¹¹ and in the end it must be shown that the theorem to be proved can be traced back to self-evident statements, i.e., statements immediately justified by mathematical intuitions. Of course, it is reasonable to ask, why are mathematical intuitions such as that 1 is smaller than 2 immediately justifying? This question cannot be answered by mathematical methods. The answer, again, is that such rational intuitions are originary presentive intuitions. Thus, PaP is the principle that reveals why such mathematical intuitions are a source of immediate justification.

Based on the foregoing achievements, we can define that a principle is ultimately elucidating if it fulfills the following two conditions:

Since UEP fulfills both conditions of Ultimately Elucidating, it is ultimately elucidating. But is UEP itself justified?

Having clarified in which sense UEP is ultimately elucidating, let us now discuss why it is ultimately elucidated. What does it mean for a principle to be ultimately elucidated? We may say:

Alternatively, we may formulate Ultimately Elucidated as follows:

In our case, of course, P = PaP. By intuiting PaP, you are not only justified in believing that PaP obtains, but PaP is also the principle that elucidates why your intuiting is immediately justifying, which means that by intuiting PaP you are intuiting the principle (namely PaP) that elucidates why your intuiting PaP is immediately justifying (because the act of intuiting is an originary presentive intuition and according to PaP every originary presentive intuition is a source of immediate justification). Let us clarify this by contrasting PaP with principles that do not fulfill Ultimately Elucidated.

Consider the principle that every perceptual experience is a source of immediate justification (PPE). PPE is true (since every perceptual experience is an originary presentive intuition). By intuiting PPE, you are immediately justified in believing that PPE obtains (which means that condition [i] in Ultimately Elucidated is fulfilled), but PPE is not the principle that elucidates why you are immediately justified in believing that PPE obtains (which means that condition [ii] in Ultimately Elucidated is not fulfilled). Thus, PPE is no ultimately elucidated principle. The same holds for the principle that every mathematical intuition is a source of immediate justification (PMI). PMI is true (since mathematical intuitions are originary presentive intuitions). By intuiting PMI, you are immediately justified in believing that PMI obtains (given that your intuiting is an originary presentive intuition), but PMI is not the principle that elucidates why you are immediately justified in believing that PMI obtains (because your intuiting PMI is not a mathematical intuition).

Note that when you have a perceptual experience of a laptop in front of you, this experience provides you with immediate justification for believing that there is a laptop in front of you, but this experience does not immediately justify you in believing that this experience is an immediate source of justification. An experience can only provide immediate justification with respect to what is originally presented within experience. In this case, what is originally presented is a laptop, not the content that this experience is an immediate source of justification. Originary presentive intuitions are a source of immediate justification, but they are neither ultimately elucidating nor ultimately elucidated. Such characteristics can only apply to epistemological principles, and we have seen that PaP is a perfect candidate for displaying these characteristics.

Here, two clarifications are appropriate. The first clarification concerns the difference between falling under a principle and knowing a principle. UEP, the basic phenomenological principle, is an internalist principle in the sense that it states that mental states, and more precisely originary presentive experiences, are our ultimate justifiers. Thus, Husserlian phenomenology is internalist in the sense of being a version of mentalism.Footnote ¹² This kind of internalism, however, does not imply that in order to be justified one needs to know the ultimate epistemological principles. An epistemological principle such as PaP is “not a principle I have to apply in order to gain knowledge; I need only fall under it” (Van Cleve Reference Van Cleve1979, 70). Walter Hopp (Reference Hopp2009, 11) discusses this in detail and concludes that Van Cleve’s dictum “is just what we find phenomenologically.”

When an ordinary person who has never cared about philosophy or phenomenology has a perceptual experience that presents to her a table, this person is immediately justified in believing that there is a table because this person falls under PaP. This person does not need to know that PaP applies in order to be justified. This is why I have called the ultimate epistemological principle ultimately elucidating and not ultimately justifying. In deference to Van Cleve, let us call this insight rule-externalism. Importantly, rule-externalism is not inconsistent with internalism in the sense of mentalism.Footnote ¹³ Only the phenomenologist, the person concerned with First Philosophy and ultimate elucidation, must attend to ultimate principles.

The second clarification concerns the validity and motivation of PaP. It would be a mistake to subscribe to the following line of reasoning: If PaP is true, then PaP fulfills Ultimately Elucidated, thus we have good reason to believe that PaP is true. This only shows us that PaP is a candidate for being the ultimate epistemological principle, but it does not entail that PaP is true or plausible. This can be seen by realizing that a principle that is inconsistent with PaP could also make such a claim. Think about the following reliabilist principle:

RP: Every reliable intuition is a source of immediate justification.Footnote ¹⁴

Now the reliabilist could rightfully point out that by having the reliable intuition that RP obtains (given that RP is true), you are immediately justified in believing RP (condition [i] of Ultimately Elucidated) and RP is the principle that elucidates why you are immediately justified in believing that RP obtains (condition [ii] of Ultimately Elucidated).

Of course, there are important differences between PaP and RP. In the next section, I shall focus on one of them, namely the accessibility of the respective principles.

3. The accessibility of PaP

In current epistemological debates, it is common to distinguish between two versions of internalism: “access internalism” (or “accessibilism”) and “mentalism.” Accessibilism is the traditional version of internalism and demands that there must be a special kind of access to what it is that makes a belief justified.

Accessibilism is clearly opposed to and inconsistent with reliabilism. This is because the reliability of one’s belief-forming processes is usually not reflectively accessible. And if it is not reflectively accessible, it cannot play a justificatory role, contrary to what is entailed by reliabilism.

The other version of internalism, mentalism, has been introduced by Conee and Feldman (Reference Conee and Feldman2004, 55) as a novel kind of internalism and refers to the claim that justifying factors must be internal to a person’s mental life.

Mentalism and accessibilism are not inconsistent, but they are different claims, and, contrary to what is sometimes suggested (cf. e.g., Swinburne Reference Swinburne and Dougherty2011, 196), mentalism does not entail accessibilism (cf. Pappas Reference Pappas and Zalta2017, sec. 6). Mentalism can avoid some well-known problems of accessibilism. For one thing, it is often objected that some animals and children clearly have justified beliefs despite the fact that they lack the sophisticated cognitive capabilities to have reflective access to their justifiers. It is plausible to assume that when a dog hears its favorite person approaching and then sees the person, the dog knows that the person is there. If it is true that dogs lack the cognitive capabilities to have reflective access to their justifiers, this is a problem for accessibilism but not for mentalism. It is not a problem for mentalism since mentalism only states that justifiers must be mental states (such as hearing a person approaching and seeing a person) without claiming that they must be reflectively accessible. Furthermore, accessibilism is often viewed as implying that if S is justified in believing that p, S must be in a position to be justified in believing that she is justified in believing that p (cf. e.g., BonJour Reference BonJour1985). Such a requirement, however, is in danger of leading to a vicious regress of justification. Mentalism, however, is not committed to such a requirement.

On the other hand, accessibilism has the advantage of clearly being internalist, while this is not so clear for mentalism. Consider the following claim: only visual experiences are justifiers. Since visual experiences are mental states, this claim is clearly mentalist (and, of course, totally implausible). This claim, however, is consistent with the following claim: only reliable experiences are justifiers, and, since only visual experiences are reliable, only visual experiences are justifiers. Of course, this claim is totally implausible, but, since it is mentalist and reliabilist at the same time, this shows that mentalism is no clear commitment to internalism.

Concerning the discussion of internalism, what can we say about our principle UEP?

1. I1: Since UEP holds that one’s ultimate justifiers are one’s originary presentive intuitions, UEP is committed to some version of mentalism.Footnote ¹⁶

2. I2: UEP is not committed to accessibilism.

3. I3: UEP is consistent with what we have called rule-externalism in section 2.

4. I4: Since Husserl supplements UEP with the claim that originary presentive intuitions gain their justificatory force precisely by virtue of their phenomenal character of originary givenness, Husserl’s version of mentalism is truly internalist and incompatible with reliabilism (or externalism in general).Footnote ¹⁷

5. I5: UEP is internally accessible in the sense that when I intuit UEP it is internally accessible to me that by intuiting UEP I intuit the principle (namely PaP) that elucidates why my intuiting UEP immediately justifies me in believing that UEP obtains.

All five points are of crucial significance, but here we are primarily interested in I5. The first thing to note is that I5 is not inconsistent with I2 or I3. PaP implies that if S has an originary presentive intuition of p, then S is (immediately) justified in believing that p whether or not S has reflective access to her justifiers and whether or not she knows that PaP obtains. But this, of course, does not rule out that S has reflective access to her justifiers and that she does know that PaP obtains. Given that PaP is true, the second thing to note is that I5 is very plausible. Since originary givenness denotes the phenomenal character of an experience, it is plausible to assume that to normal human beings, typically, it is accessible whether or not they have an originary presentive intuition. Thus, when I intuit PaP, and this act of intuiting is an originary presentive intuition, then it is accessible to me that my intuiting PaP is an originary presentive intuition. The third thing to note is that the reliabilist principle RP discussed in the previous section does not exhibit this feature of internal accessibility. This is because reliability, in contrast to originary givenness, is no factor that is internally accessible.

Accordingly, we can formulate a stronger definition of what it means for a principle to be ultimately elucidated that satisfies the requirement for internal accessibility:

The reliabilist principle RP may be able to satisfy conditions (i) and (ii) but it cannot satisfy (iii). PaP satisfies all three conditions. Condition (iii) makes the ultimate principle truly self-justifying: By intuiting PaP, you are immediately justified in believing that PaP obtains, you are intuiting the principle that elucidates why you are immediately justified in believing that PaP obtains, and by having this intuition it is internally accessible to you that by intuiting PaP you intuit the principle that elucidates why your intuiting PaP immediately justifies you in believing that PaP obtains. In the next section, we shall shed more light on the systematic role UEP plays within a phenomenological epistemology.

4. The role of UEP within a phenomenological epistemology

Although UEP is the centerpiece of a phenomenological epistemology as it is the phenomenologist’s ultimately elucidating and ultimately elucidated principle, this does not mean that UEP is the finalization or even the beginning of a phenomenological epistemology. UEP tells us that originary presentive intuitions are a source of immediate justification and that they are the ultimate source of justification. However, there are further crucial phenomenological-epistemological principles. For instance, in this paper we have only touched on the question of why originary presentive intuitions are a source of justification. Husserl’s genuinely phenomenological answer to this question is that they are simply by virtue of their phenomenal character of originary givenness (cf. Husserl Reference Husserl2008, 342–43; 1982, 36). Let us call the claim that certain experiences gain their justificatory force by their distinctive, justification-conferring phenomenal character the phenomenological conception of experiential justification (PCEJ).Footnote ¹⁸ The Husserlian version of PCEJ has it that this justification-conferring phenomenal character is the character of originary givenness.

Of course, Husserlian PCEJ and PaP are related in the sense that Husserlian PCEJ implies PaP. Arguing in favor of Husserlian PCEJ, thus, means arguing in favor of PaP. Arguing in favor of PaP can motivate PCEJ. Another related phenomenological principle we may dub Phenomenological Internalism:

Phenomenological Internalism is neither identical to nor implied by (Husserlian) PCEJ or PaP, but of course these principles are close enough that arguing in favor of one of them can help to motivate the other ones. This is why UEP, although being the ultimately elucidating and ultimately elucidated principle, is not the finalization of a phenomenological epistemology. There are other phenomenological-epistemological principles that are not implied (but are elucidated) by UEP.

Furthermore, it would be misleading to claim that the phenomenologist can simply begin with UEP. Of course, if Husserl is right, it is not only possible to provide arguments in favor of UEP (and the other phenomenological-epistemological principles) and to motivate UEP but also to intuit UEP in the sense of having an originary presentive intuition with respect to UEP that immediately justifies believing UEP. However, such an a priori apodictic intuition, for Husserl, is an eidetic intuition and as such the product of eidetic variations. Dirk Fonfara outlines the method of eidetic variation as follows: “One begins with an experienced or imagined intuitively given object [Gegenständlichkeit] that serves as a leading example and is varied in one’s imagination at will” (Husserl Reference Husserl2012, xix). Husserl elucidates that “[eidetic] intuition is ideative abstraction that is constituted on the basis of individual intuition. Such individual intuition, however, can be both perception and phantasy. Positings of existence are completely irrelevant” (Husserl Reference Husserl1987, 124). Husserl calls these individual intuitions the base (Unterlage) of eidetic intuition (cf. Husserl Reference Husserl1987, 126–27; cf. also Rinofner-Kreidl Reference Rinofner-Kreidl 2000, 135).

It is one of Husserl’s core convictions (and typical for phenomenological investigations) that theories or principles should not be constructed “from above” (top down) but “from below” (bottom up) in the sense of beginning with concrete cases (cf. Husserl Reference Husserl1996, 326–27).Footnote ²⁰ Accordingly, if you want to disclose the nature of justification, you should begin by descriptively analyzing concrete justification-conferring experiences instead of postulating a general principle. Beginning with concrete cases can help you to “see,” i.e., to have an originary presentive intuition of a general phenomenological-epistemological principle such as PaP.Footnote ²¹