The most important aspect of what is called categories is that they are not products of our thought or of reflecting reality, but that we meet them ready-made, as it were. We only become aware of them, and of the fact that they have always been there in our minds, while coping with all kinds of things.
To know how a certain thing behaves, you must observe it, do experiments in which you change its environment to see how its behavior is affected, and so forth. This is a process in which you learn something that you did not know before.
The same is true about visiting a new region: you learn to know new people, new landscapes, and new customs. All this you were previously ignorant of.
This is not what happens with the categories. Although you do not know them, they constantly work in your mind. All you need is to be made attentive to them.
When you were experimenting with the thing mentioned above, although you did not think of it, you somehow knew that that thing was different from any other thing, that it had its own properties that you were about to know, that it had consistency, that it was located among other things both in space and in time, and that it was exposed to causal influences from outside.
The same applies when you travel to unknown regions: the people there are different from others; they are not excepted from universal causal influence; they are not timeless or spaceless beings; they are not ubiquitous in the universe but are located, and their bodies are not diaphanous but material, and so forth.
Thus our categories were always present, although we did not notice them, allowing us to interact with those things, to experience them, and to enhance our knowledge. But, unlike what happens with the normal process of knowledge, we cannot indicate their origin in our mind. Instead, they structure our minds, and we can only describe such structures and not explain how they form.
When scientists, particularly neurologists, discuss the origin of our consciousness, they already use those categories too, i.e., they cannot avoid using them. This is why, in fact, they cannot explain how they appeared in the human mind.
Making phenomenological descriptions does not help either because since any experience of a sentient being requires them: the moment when such a being also actively uses them is necessarily not the moment when they occur in its psyche. And our observation cannot go beyond activity, which is the sole basis of it.
This case is similar to that of a newborn child who immediately recognizes his mother’s voice. We can observe that through how it behaves and becomes tranquil once the mother starts speaking with it. This calming is, for us, proof, that he recognizes the mother’s voice and that he is familiar with it.
Nevertheless, when and how he started becoming familiar with that voice is another question. As far into the past as we want to extend our inquiry during the intrauterine development of the fetus, we can never reach the moment when this fetus starts knowing about that voice. We can only see its bodily reactions to that voice, which occur long thereafter.
Categories are not produced by our knowledge. They are rather expressions of the fact that we are inhabitants of a universe that functions through them. Categories are building us up; they order all the elements of our body from the moment we have been conceived as fertilized eggs in the uterus of our mothers up until today.
Of course, there is another question concerning the form in which we become aware of them. An animal likely has a different experience of space, time, consistency, or causality than us. The same is true concerning people living in different cultures than ours, who also might experience these categories differently. Still, their structures are always there.
Much as an animal recognizes causality differently than we humans (for example, in the imminence of an attack by another prey animal lurking around it), the formal structure of causality is the same as ours. It is aware of something – the danger – that is about to change its ordinary life, i.e., to have an effect on that life.
That means there is a continuity between mind and reality, a continuity that grounds all our knowledge. As particular as our knowledge is, this particularity cannot remove it. The study of this continuity is what philosophers have always called metaphysics.
Philosophy deals with an object far above any concrete object of any science, and, what is more, this object makes the individual objects of particular sciences intelligible. Aristotle, in antiquity, called metaphysics the science of the first principles or primary causes (Aristotle, Metaphysics, 981b28). Kant, in modernity, called metaphysics the science of ‘all rational principles from mere concepts’ (Im. Kant, Critique of Pure Reason A841/B869).
In the case of categories, you cannot speak about the reflection of the external world into our minds. Even such a process of reflection would already be a category-based process. This is why one can say that, through the fact that man recognizes them, the universe itself reaches self-consciousness.
All processes happening in the universe take place according to such fundamental categories. However, in the same way in which plurality – as a category – can take an infinity of forms, this self-awareness of the universe can happen in an infinite number of ways.
This is because the interactions between possible consciousness and their environment are determined by categories and the history of those interactions. For example, a human being hears according to the category of causality in that it receives the external influence of a sound wave.
However, it can happen that, due to the continuous presence of the sound, that human being could overhear it, ignore it, and, in fact, not hear it at all.
Yes, experiencing categories may be different, which Hegel, for example, also means through his phenomenological approach to philosophy. Human history can evolve from one paradigm of thought to another, from one worldview to another, because it is supported by the same categories that receive different incarnations in different worldviews.
Did the categorical structure of the world change with the Copernican Revolution? Obviously not. All the planets and the Sun continued to be separate entities, i.e., unities. They build a plurality because they are different from each other. They are causally related as before, although now, the form of the causal network in which they exist is different from in Ptolemaic astronomy. And so forth.