BODY AND PRACTICE IN KANT

CAUSALITY AND COMMON SENSE PHYSICS 303
accordingly (even if this is how we may chose to describe the event). In
the midst of the game there is no time for such calculation. You simply
act and in these acts is embedded your knowledge of objective time,
which is nothing other than your knowledge of how the ball and yourself
move, which is through and through a knowledge-in-practice and
identical with your practice of interaction with the ball.
The same point may, of course, also be stated at a more general level,
when we start to reflect on our general way of interacting with the
physical objects of our environment. Just as in the ballgame example, we
would never be able to interact with those objects if we did not know how
they moved in time, which is the same as knowing objective time.
Moreover, this knowledge is normally not something of which we are
aware, or which is present in the form of an explicit calculation, but
merely as a knowledge-in-practice, that is, the practice of interaction
itself.
I think we are here approaching one of the basic ideas of the
Critique, expressed for instance in the Refutation of idealism, that
objective time determination is possible only in a world of externally
existing objects, objects, moreover, with which we ourselves interact. In
the Refutation of idealism and elsewhere in the Critique Kant does not
discuss exactly how this interaction takes place or how it is related to
objective time determination. The above reflections have supplied us
with a model of this, however, and it has led us to the same conclusion:
objective time determination is possible only in a world of externally
existing objects, objects, moreover, with which we interact. It is so
because to know time objectively and to know how to interact is one and
the same thing, and the one is not conceivable without the other.
Alternatively, we may say that by learning to interact with the objects
of the world, objects that either move or are at rest relative to ourselves,
we acquire a primitive physics. 19 We learn to calculate not only the
spatial sizes and positions of objects, but also their movements. In short,
we learn to know the world as a dynamic network of objects and forces
dynamically connected in an objective time order, that is, as a series of
causally connected events. When the child first acquires this knowledge
in the sensorimotor period, this knowledge is a knowledge-in-practice,
because this is the only kind of knowledge available to the child of this
period. However, as I have argued, we may also see this knowledge-in-
19 We may here draw a parallel to Rousseau’s Émile where he describes the
process of a child learning to interact with the objects of his environment, as an
experimental physics, c.f. Rousseau (1979), 125.