Husserlâs Philosophy of Science
When we think of philosophy of science, we think of Ernst Mach, Rudolf Carnap, Carl Hempel, Ernest Nagel, W. V. Quine, Thomas Kuhn, Patrick Suppes, and others. We do not at first think of Edmund Husserl, noted for launching phenomenology as the reflective, first-person science of consciousnessâin contrast with physics taken as the hypotheticodeductive, third-person science of nature at its most basic level. Yet Husserl explicitly addressed many issues in the foundations of mathematics, logic, and science at a time when the philosophy of science was taking shape around twentieth-century mathematical physics and mathematical logic. The term of art in Husserlâs day and milieu was not philosophy of science, but theory of science, or Wissenschaftslehre. In his lifetime Husserl had direct contact with Weierstrass, Kronecker, Cantor, Frege, Hilbert, Schlick, and Carnap, and his work was known to Tarski and Gödel. That is to say, Husserl was hardly out of the loop of thinkers then working on the foundations of mathematics, logic, and science. Husserl was not of course an architect of relativity theory, non-Euclidian geometry, number theory, set theory, or quantifier logic. But he was ever expanding a wide-ranging philosophy that addressed all these âsciencesâ (in the wide sense of the term then in vogue) as well as psychology and phenomenology.
Husserlâs first book was published in 1891 as Philosophie der Arithmetik. Partly due to Fregeâs (understandable) misreading, that book was viewed as a psychologistic reduction of numbers to merely psychological activities of grouping and counting. A more careful and subtle study finds Husserl carrying out an analysis of the concepts of number and totality, which intentionally represent numbers and totalities. (This sympathetic reading of Husserlâs first book is outlined by Dallas Willard in his introduction to his English translation of Husserlâs book, Philosophy of Arithmetic; see in particular pp. xxiâxxix.) In terms of Husserlâs mature thought, he was aiming at an analysis of the sense (Sinn) of number and the coordinate essence (Wesen) of number, where a sense is an ideal intentional content and an essence is an ideal property. But these notions Husserl developed only later in his full theory of intentionality and its attendant ontology.
Husserlâs first mature work was the Logical Investigations, first published in 1900â1901 in three volumes spanning some 1,000 pages. In that work Husserl developed a unified philosophical system of logic, semantics, ontology, phenomenology, and epistemology. As Husserl explained in the opening volume, titled âProlegomena to Pure Logic,â that system was inspired in good measure by Bernard Bolzanoâs 1837 groundbreaking opus Theory of Science (Wissenschaftslehre) (1972). Accordingly, Husserl was seeking inter alia a basic account of the logical and epistemological structure of any science. A crucial part of the Investigations was Husserlâs detailed theory of intentionality, the foundation of phenomenology, which was followed by an extended analysis of evidence or âintuitionâ (Anschauung ) in the theory of knowledge, starting with sense perception. Issues of logic, ontology, intentionality theory, and epistemology thus frame the background for Husserlâs subsequent programmatic presentation of the discipline of phenomenology in Ideas I (1913).
Empirical science, from physics to psychology, was prominent in the horizon of Husserlâs phenomenology (even in his technical sense of horizon ). Phenomenology was to be sharply distinguished from empirical psychology, which would include todayâs cognitive science, because phenomenology seeks ideal structures of meaning (Sinn) in the content of experience, whereas empirical psychology seeks contingent patterns of mental activity and its causes, even as in todayâs functionalist models in cognitive science and cognitive neuroscience. Physics too lies beyond the scope of phenomenology because phenomenology (in one range of analysis) is to bracket the existence and the essence of physical nature (even, we note today, the essence of the neural activities on which our consciousness depends) in order precisely to shift our attention to the way we experience things in nature. Thus we shift our attention away from the objects of our consciousness (in everyday perception or indeed in the abstract thinking we might practice in doing mathematical physics), and we turn instead to our own forms of experience, and therewith to their contents or meanings. Armed with phenomenological analyses of perception, judgment, and so forth, we will however return to an analysis of the structure of knowledge, ranging from our familiar knowledge of everyday affairs to our collective scientific knowledge, as in mathematical physics. That is where the Logical Investigations ends: poised for more specific analyses of formations of knowledge, say, in the natural sciences. As we consider below, philosophy of science followed out such an analysis not least in the work of Rudolf Carnap, in ways surprisingly congenial to Husserlâs intentionality based âtheory of science.â Keep in mind that Husserlâs conception of intentionality and phenomenology is framed by his wider theory of science, ĂŒberhaupt.
Husserlâs last wave of work, during the period 1935â38, was collected in the posthumous book called The Crisis of European Sciences and Transcendental Phenomenology. The intellectual and spiritual crisis Husserl saw resides in the way in which mathematical physics has lost touch with everyday human experience. Galileoâs vision of science began the ideal of a âmathematizationâ of nature, which in the early twentieth century produced first general relativity theory and then quantum theory. As widely discussed, both relativity theory and quantum theory seem incompatible with our Lebenswelt (life-world) experience and our everyday knowledge of the world around usâeven though science begins with everyday perceptual observation and proceeds with work in the laboratory, at the computer screen, and so forth. Husserl addressed this problem concerning the foundations of twentieth-century physics in a âtranscendentalâ critique of mathematical physics.
As Husserlâs analysis of science unfolded from his early work in the Logical Investigations to his late work in the Crisis, we find a strong tension. The early vision is full of hope for the model of any science as a formal, ideally mathematical theory of a given domain supported by evident experience or intuition of an appropriate type. But the late vision finds a crisis, as mathematical physics no longer seems tied to human experience, and we can no longer really understand what mathematical physicsâEinsteinian physics in particularâsays about the world around us.
Our present task is to explore certain issues in a Husserlian philosophy of science, looking to its foundation in a Husserlian theory of intentionality and attendant ontology. We will be pressing three themes further than Husserl did. The first theme is the indexical structure of perception (seeing âthis such-and-suchâ), which is the form of experience that serves as the evidential base of any empirical science. The second theme is the âglobalâ indexicality of our concepts of things in nature (such as the concept tree), concepts that by their very meaning represent things in our surrounding world, or Umwelt. The third theme is the ontological dependence of our theories, even in mathematical physics, on historical human intentional activities.
The results of this exploration allow a new view of the formal and material aspects of science, which we shall bring into relief by drawing on Michael Friedmanâs Kantian-Carnapian-Kuhnian account of science.
Husserlâs Unified Theory: A Theory of Theory, Essence, Meaning, Part/Whole, Intentionality, Evidenceâand Thus Empirical Science
Husserlâs Logical Investigations (1900â1901) unfolds a unified system of logic, ontology, phenomenology, and epistemology: defining a framework within which we may outline a Husserlian philosophy of science. The Investigations includes seven interrelated studies. The Prolegomena outlines a theory of âpure logic,â which prefigures the development of semantics or metalogic by Carnap, Tarski, and others. Investigation I offers a theory of linguistic expression, meaning, and reference (with some similarity to Fregeâs). Investigation II offers a theory of universals, or âideal speciesâ or essences (Wesen), combining elements of the Platonic and Aristotelian views of universals. Investigation III is a theory of part and whole, including the notion of âmoment,â or dependent part. Investigation IV applies that part/whole ontology to ideal meanings in a theory of âgrammar.â Investigation V is a long presentation of Husserlâs groundbreaking theory of intentionality, carefully distinguishing act, content, and object of consciousness. That theory of intentionality is the foundation of Husserlâs conception of phenomenology. Finally, Investigation VI develops a phenomenological theory of knowledge, featuring the character of evidence in intuition, including visual perception. What is remarkable, and too little appreciated, is the tightly knit unity of Husserlâs system. In my view Husserl joins Aristotle and Kant among the most systematic of philosophers.1
Looking to philosophy of science, I should like to emphasize three parts of Husserlâs system: his theory of theories, his theory of intentionality, and his theory of evidence. Husserlâs system as a whole is a wide-ranging theory that includes a theory of what it is to be a theory. That is, Husserlâs theory of almost everything includes a metatheory that applies to the overall theory. And the metatheory is itself a part of the theory, in the sense explicated in Husserlâs theory of parts/wholes. (How does this play today in light of the results in metalogic that followed in Husserlâs wake?)
Husserlâs theory of theory (Prolegomena) holds that a theory is a system of propositions, which are ideal meanings (compare Bolzanoâs notion of Satz an sich and Fregeâs notion of Sinn or Gedanke). A deductive theory includes deductive consequences of propositions in the theory; an inductive theory includes propositions made probable (âmotivatedâ) by other propositions in the theory. Each theory forms a semantically coherent group of propositions that characterize a domain, or field of knowledge. The propositions in a theory develop âlaws of essenceâ about the domain of the theory, that is, they specify the essence (Wesen), or properties, of objects in that domain. All this should sound familiar to us today. But notice that the elements in a theory are propositions, ideal propositional meanings (Sinne), rather than sentences in a language (as subsequent logicians, such as Carnap, Quine, and others, assume). And bear in mind that in Husserlâs mature ontology, essences and meanings are categorially distinct. Meanings are ideal intentional contents that semantically represent objects and their properties or essences. As an approximation, essences are like Aristotelian universals, while meanings are like Fregean Sinne.
If a theory is a system of propositions, what kind of entities are propositions for Husserl? Propositions are meanings that are propositional in form (expressible by a complete declarative sentence). But meanings are, for Husserl, ideal contents of intentional acts of consciousness. In the Investigations, Husserl identified ideal meanings with ideal species of intentional acts: A meaning is the ideal species of an experience of thinking or seeing or whatever. So a proposition is the ideal species or type of thinking that such-and-such is the case. By the time Husserl wrote Ideas I, however, he had come to hold instead that meanings are their own kind of ideal entities: not species of intentional act, but meanings sui generis, like Fregean Sinne, if you will.
What makes a theory true, for Husserl, is its correctly representing the essence of objects in its domain. But truth is distinct from evidence. What makes a theory count as knowledge of its domain is the evidence supporting it. In Husserlâs phenomenological theory of knowledge (Investigation VI), evidence consists in the phenomenological character of âevidenceâ (Evidenz) or âintuitive fullnessâ or âfulfillment.â An act of intuition (Anschauung) is an intentional act of consciousness that has the character of intuitiveness, that is, intuitive fullness or evidentness. When I see that red ball, part of the way the object is experienced is with a character of sensory evidence. I do not merely think of a red ball, I seeâor, some insist, seem to seeâa red ball. If I then judge visually that it is a red ball, my judgment has a meaning supported by the character of intuitive evidence in my act of so judging.
Husserl distinguishes some three types of intuition. Sensory or empirical intuition is found in sensory perception. Essential intuition (Wesenschau ) consists in coming to âseeâ something about an essence or ideal species of object, for instance, that a triangle has angles totaling 180 degrees, coming to see this perhaps through deduction or through eidetic variation. Transcendental phenomenological intuition consists in grasping the structure of an experience as lived, including its ideal intentional content or meaning, perhaps through bracketing or epochĂ©. The techniques for achieving these types of intuition are very different, and beyond the scope of our discussion. I wish only to stress that there are different types of evident or intuitive experience or judgment, achieved in different ways.
A distinguishing feature of Husserlâs theory of theory, and thus of knowledge, including science, is his view that a theory is a form of intentionality, a system of propositions that serve as contents of judgments about a given domain of objects. In Formal and Transcendental Logic (1929), Husserl treats formal logic, where a theory is a formal or symbolic deductive system, as requiring a foundation in transcendental logic, by which Husserl means formal logic grounded in intentionality. As we might say today, a formal theory (a system of symbols, rules of inference, axiomatic sentences) is accompanied by a semantics, a system of assignments of meanings to relevant expressions in the formal theory. But meanings, for Husserl, are ideal contents of intentional acts of thought, perception, and so forth. Thus we find the later Husserl amplifying the early Husserl of the Logical Investigations. Husserlâs theory of scientific knowledge flows from this intentionalist account of a theory supported by appropriate evidence in perceptual experience.
In Husserlâs theory of knowledge, we may say that empirical knowledge consists in forming empirical judgments with appropriate sensory intuitive evidence. As Quine would say, empirical knowledge begins with observation, with sensory perception of objects. Husserl would specify then that an observation consists in a perceptual judgment, an intentional act with a certain propositional content and a certain character of sensory evidence.
When does empirical knowledge develop into what we call a science like physics? In Husserlâs scheme, a science like physics is an accumulation of empirical knowledge produced by a community of intentional subjects building on the work of others. A scientific theory, we may say, is thus a theoryâa system of propositions (ideal meanings) about a domain of objectsâthat is supported by evidence (intuitive fulfillment) in observations (perceptual experiences) and put forth in judgments performed by individuals working collectively in the relevant scientific community.
In the Crisis (1935â38), drawing on results as early as Ideas II (1912), Husserl characterized what he called the sedimentation of knowledge. Traditional beliefs are sedimented propositions that we typically share while having little if any explicit awareness of these belief-contents. These may be called background beliefs. But mathematical knowledge too is sedimented. Husserl focuses on Euclidian geometry, the system of propositions we have inherited and developed since Euclid. After Galileo, Husserl emphasizes, modern European science developed a vision of the mathematization of nature. That is, Husserl argues at length, physics after Newton came to lay down laws of natureâlaws of motion and gravityâthat are expressed in mathematical language, starting with the calculus. The calculus itself rests on Cartesian analytic...