Kant’s Philosophy: Metaphysics, Science, and A Priori Knowledge
**Metaphysics and Science in Kant’s Philosophy**
In Kant’s *Critique of Pure Reason*, metaphysics is closely related to natural science. Metaphysics represents the inevitable tendency of reason to ask questions it cannot answer, such as those about God, the soul, and the world. Nature has burdened reason with this inclination to pose questions that transcend experience.
For Kant, knowledge pertains to phenomena, which are empirical objects. While categories apply to such objects, the ideas of reason do not apply to objects of experience, as they deal with supersensible objects that cannot be given in any possible experience.
Metaphysics is not a science because, although it is formed by experience and reason, the conditions of knowledge are both the subject matter of impressions and a priori forms (the empirical and the pure). Knowledge involves objects and a priori forms, so scientific judgments contain both reason and experience. This allows for the advancement of knowledge, while the a priori character means that they are rational judgments in which the predicate cannot be denied without contradiction.
This is evident in the scientific revolution that occurred in mathematics and physics with Galileo and his experiments on falling bodies. He noticed that reason recognized in nature what it imposed on it.
Such judgments are not given a priori in metaphysics, as it purports to be based on knowledge from experience alone. Metaphysics refers to the knowledge of phenomena and the deduction of a priori forms of understanding and conditions of the possibility of intellectual knowledge of the objects of experience.
Kant believes that the object itself is unknowable. If a priori forms are removed, it becomes impossible to know the empirical object.
The concepts of understanding are not false; they are pure, empty categories whose origin is not empirical and can be applied to empirical objects through intuition.
The validity of categories derives not from their a priori origin but from their role in enabling the possibility of knowing the objects of experience intellectually.
**Experience and A Priori Knowledge**
All our knowledge begins with experience, but not all of it arises from experience. Knowledge is given by experience and by the subject because of what precedes experience and what comes from it (empirical knowledge and a priori knowledge). It is not mixed with pure experience (past or future). Kant states in the introduction to metaphysics that someone who undermines the foundations of their house could not know in advance that it would fall; they would have to wait for the event of its fall to know. Here, he refers to causation in Hume (who awoke him from his dogmatic slumber). Hume believed that causation was a rule drawn from experience. For example, smoke follows fire, and if this happens many times, we think it will happen similarly in the future. However, this thought, based on custom, generates a belief that cannot justify universal and necessary scientific knowledge but only probability.
Judgments of science (mathematics and physics) are synthetic a priori judgments: universal, necessary, rational, and empirical as well. Causality establishes the necessary connection between phenomena. This is a category, a pure concept of understanding, which applies through intuition (presupposing space and time or a priori forms of sensibility) to the regularities of mathematics and physics. Just as Thales based his figure on the triangle to apply his theorem empirically, or Galileo drew on experience to support his laws of falling bodies, scientific laws do not solely come from empirical knowledge or pure reason. Instead, after observing experience, reason applies causality and makes the judgment a scientific law. This is where Kant differs from Hume. We say that intellectual knowledge is discursive and sensed, and what cannot be thought (concepts without intuitions are empty, and intuitions without concepts are blind).
Regarding experience, we say it is empirical since the concepts of understanding are empty without the data of experience (a priori forms have to apply to the data of empirical knowledge). However, this empirical knowledge is based on transcendental, a priori conditions that allow for the knowledge of empirical objects. Unlike Kant, thinking and knowing are distinct because one can think whatever they want, provided they do not contradict themselves, while knowledge must be grounded in both the empirical and a priori forms.
By imposing transcendental conditions on phenomena, we obtain empirical objects, which are knowable. We can perceive the phenomenon but not the thing itself (the noumenon).