and a table that we originally used for establishing the standard of measurement—can we imagine the idea of a line, for example. We imagine the line not as the edge of a table but as something that is not in the world anymore and that will guide us in the future when establishing new rules for measurement. This imagined line cannot be found in the world, and yet it is not nothing: it is the idea that will inform our future measurement. The idea of a line ceases to be a practical tool; it becomes a theoretical notion. According to the Western tradition, theoretical understanding is primary.
However, Husserl also points out that the ancient Greeks’ idealization of geometry was originally still an idealization taken from the world in which they lived, and intrinsically related to it. Only when Galileo turns this understanding upside down and assumes that the world is geometrical does the formalization of knowledge begin (as I have discussed in the previous chapter).
Without reflecting on the sedimented nature of knowledge that informs our experience, we forget that we understand nature as it was defined from Galileo onward. Galileo’s new methodology is not about the world we live in, as it was for Aristotle.20 Galileo’s investigations are not concerned with particular things and their appearances; he is not interested in the way things are. He wants to discover laws that “all bodies” are ruled by.21 While for Plato unchanging ideas were reality itself, in which our changing everyday world participates, Galileo accepts the sedimented nature of geometry originally derived from the world of our living, and turns it around. From then on, nature is mathematical: “written in mathematical language, and its characters are triangles, circles, and other geometrical figures.” How else could humans understand it? They would lose their way “pointlessly in a dark labyrinth.”22
Heidegger suggests that Galileo begins with a hypothesis about certain observed phenomena—for example, the fall of a particular object—and postulates laws that will cover all cases of those phenomena. In order to do so, he must make use of mathematics and the laws of uniform motion of time and equivalence between all bodies.23 To frame nature for scientific observation in a particular way, Galileo presupposes these notions in advance. We cannot observe two different objects falling at the same speed. Only through a priori positing the equivalence of mass and motion of any and every object can we measure and calculate the speed. This calculated speed is not a “speed of things” that we encounter in our everyday experience.
René Descartes, in his search for certainty of knowledge, extends and appropriates this scientific methodology for knowledge per se.24 Modern epistemology becomes the first philosophy; it assumes the disinterested attitude of looking at objects that we have already transformed into equivalent objects for scientific investigation.
Heidegger extends his own consideration of the scientific attitude and claims that our initial understanding of things is defined by the public anonym. We always think in terms of “everyone and no one.” This way of understanding leads humans to become lost in the world and among things; and the care and concern that we all feel about the world, others, and ourselves becomes a concern for things only.25 Heidegger insists that, at present, the public anonym is the voice of the modern mathematical project of the sciences, and the essence of technology. The problem is that we cannot simply recover the life-world from oblivion.26 We have already constituted the life-world according to modern science. Heidegger’s different understanding of humans and their Being in the world transforms Husserl’s insight regarding the forgetfulness of the sciences and their disregard for their original starting point, the life-world.
Heidegger transforms the life-world and the transcendental ego by shifting the focus from consciousness as the ground of meaning constitution to the living being in the world.27 Very schematically, we can say that Heidegger transforms Husserl’s notions of intentionality of consciousness by recasting it: intentionality is severed from the ego and the idea of the constitution of meaning is reframed. In Heidegger, meaning is not constituted by the transcendental ego; rather, the world is the meaning-constituting horizon. Husserl’s idea of internal time-consciousness becomes Dasein’s temporality and historicity. Moreover, Heidegger realizes that Husserl’s insight regarding categorial intuition is important; he goes further by questioning the traditional understanding of categories.28 Heidegger declares that categories can define only things, never human beings.
Likewise, Heidegger takes up Husserl’s idea of the a priori and adapts it for his ontological project. We can discern two paths here. On the one hand, the a priori is tied to his understanding of the constitution of meaning whereby we let beings be as they show themselves to us, and we realize that we understand them through our dealings with them.29 Dasein is the space that opens the meaningful world because we live there and we deal with things as they relate to our projects. In this instance, the a priori is historical: we disclose things according to our place in history. For us a thunderstorm is not a sign of Zeus’s anger but the result of electrostatic discharge in the atmosphere. On the other hand, the formal a priori is a part of the modern mathematical project. One of Heidegger’s insights is that the modern scientific project is derived from, and yet overthrows, the Greek meaning of τἀ μαθήματα (ta mathemata). For the ancient Greeks, ta mathemata meant learning and teaching in the sense that we can learn about only something that we already know. However, Heidegger argues that modern science changes the original meaning of this a priori of knowing—knowing something that is derived from our initial encounter with things and our dealings with them. Modern science—through the assumption that worldly structure is mathematically a priori—transforms this original meaning of knowing things into a formal framework that, in advance, takes for granted that nature is mathematical and can be mathematically ordered. Only by restricting nature to a mathematical manifold can we find the universal natural laws and “facts” that are subject to those laws.
To put it differently, Heidegger’s first sense of a priori relates to his notion of the original essence of truth, whereby we let beings be as they are; the second is related to the scientific and technological enframing of nature into a mathematical manifold and the new scientific way of understanding objectively present things, whereby truth is regarded “as a characteristic of knowledge.”30 Heidegger comments on the correspondence theory of truth, which proposes that truth is the property of a sentence. According to this theory, we judge things by “matching up” words to things in the world. However, Heidegger insists that the correspondence theory of truth must be based on a more primordial notion of truth; in other words, on truth as a disclosure, as the revelation of things and their being as they are manifest to humans. Hence, the correspondence is derivative from this original disclosure of things; the correspondence theory of truth cannot be the only sense in which we can think about truth.
For Kant, the intermediary between an object and our thinking is intuition. Given that intuition is not cognitive, a thing and an assertion cannot be directly connected; intuition is the gap between our thinking and the thing in the world. Kant recognizes that without sensibility there is no intuition, but without cognition there is no possibility of understanding what is given to us in intuition. The direct connection is between an object and intuition and not between an object and an assertion. As Heidegger stresses, without pure concepts of understanding, such as quality, quantity, relation, modality,31 through a “power of judgment,” the object would remain “undetermined.”32 In order to see something as something, we synthesize “the manifold pure intuition” with the imagination, and these “pure categories” bring it into the unity of our thinking.33 We do not stand in the midst of a superabundance of different sensations that assault our senses. Heidegger, discussing Kant, states that pure understanding brings “to a stand” intuition, which would be meaningless to us without a thought.34 Through the categories of pure understanding, the correspondence between our judgment and the (previously) undefined object is constituted.35 Kant states: “Thoughts without content are empty; intuitions without concepts are blind.”36 Hence a thing in its thingness, its objectivity, is “determined as object” through the unity of intuition and thought (WT, B, II, § 7a, 184; italics in original). Thought provides the pure categories of understanding