Rationalism and the difficulty with definition by equation

Some notes following Oakeshott, 'Rationalism in Politics'

As an intellectual posture, the Rationalist is perhaps characterised foremost by their opposition to practical knowledge. Their notion is that knowledge, properly speaking, is that which can be raised to the reflective sphere and thus expressed as a set of propositions. This is technical knowledge; in other words, the knowledge of the book—for what they take as knowledge is that which can be put into a book. Opposing this—and ultimately inseparable from it, Oakeshott reminds us—is practical knowledge. Practical knowledge, while distinguishable only in abstract, is that contrary form of knowledge which is not susceptible to precise formulation. These two are always found together—for instance, in the taste necessarily exercised in the application of a precept. Yet what characterises the Rationalist, says Oakeshott:

is the assertion that what I have called practical knowledge is not knowledge at all, the assertion that, properly speaking, there is no knowledge which is not technical knowledge.

We might most clearly evince the meaning of this contrast, and the impossibility of the Rationalist position, by concrete example. Take, for instance, the definition of a word: X = A + B. Here the form, as ever for definitions, is that of an equation. The known components on one side (A, B) are rendered by our understanding so as to answer to the meaning of the unknown term (X). Yet note immediately: this depends on the meaning of those known components, which is taken as an essential given. Suppose then that we ask for definitions of these, inevitably this would be given also in the form of an equation; and then, we ask for definitions of the components of this answer; and so on, towards an infinite regress.

Everywhere the Rationalist is obsessed with the solidity of their foundations. Yet here, by following somewhat pedantically the chain of equations, we find no such foundation—only a trail stretching far over the horizon. And while we have not walked this all the way, it is reasonable enough to presume it will indeed go on forever; since how could we ever escape this chain, which arises from the very nature of this process of definition by equation? As an alternative we might follow a somewhat different path. Suppose instead of taking up a standard dictionary, we take an etymological dictionary. Here we follow another chain, and yet here we find a hint of something more:

What would old Hegel say in the next world if he heard the general (Allgemeine) in German and Norse means nothing but the common land (Gemeinland), and the particular (Sundre, Besondere) nothing but the separate property divided off from the common land?

While once more an infinite regress seems entirely possible, we also see a potential way out; for everywhere the root of words seems peculiarly to lead back to activity and concrete experience. What if it is not the mathematical certainty of any equation on which we stand but the actuality of the ground itself?