Human beings do not have pure intellectual knowledge devoid of sense knowledge or pure sense knowledge without the involvement of the intellect. In every concept we distinguish both intellectual and sensible elements. In us there are no innate ideas. Ideas have their sources outside the intellect and the intellect must derive them from the things. “There is nothing in the intellect which has not been first to the senses except the intellect itself”. Thus in all cases of our intellectual knowledge there is a collaboration of a priori and a posteriori elements. The a posteriori elements come from the senses and ultimately make up an image (phantasm). The a priori elements come from the intellect itself. They consist in the basic ontological affirmations of which the first one is ‘this is’ or’ ‘something exists’.
Substantial unity between intellect and senses
The substantial unity implies not only the unity of body and soul in a human being but also that of human senses and intellect. As the soul is to the body, so the intellect to the senses. Intellect does not stand above the senses but it is in them so that an object never affects the senses without at the same time affecting the intellect. Whatever enters the human senses at once falls within the range of the human intellect. In reality there is only one knowing subject, composed of both body and soul. This means that the intellect is already at work in the senses and in the formation of the images. It animates the formation of the images and then through the activity of abstraction produces the universal idea.
All human knowledge is analogical
Analogy is application of a term to different realities partly with the same meaning and partly with a different meaning. All our human knowledge is analogical, and this is especially true of immaterial realities. Words are indicative of reality. There is no one to one correspondence between the words we use and the things they refer to. We do not have pure knowledge of anything. All knowledge is therefore analogical. In the analogical knowledge of an immaterial reality, we use a material representation. Our representation is partially true and partially false, and what we mean implies affirmation, negation and transcendence.. For example, we really mean that the soul permeates the whole body (affirmation), not however in the manner of a fluid (negation), but in a more perfect, immaterial way (transcendence).
Is there intuitive knowledge in human beings?
A pure spirit knows through intuition, that is, directly and without the mediation of mental pictures or representation. Human beings are finite spirits-in-matter. In them the intuition is so imperfect that it is not intuition in the strict sense of the term. Only the first principles of all knowledge may be considered as intuitive knowledge in human beings. But of themselves they yield no knowledge since they are only potentially conscious and need the intervention of an object derived through the senses in order to emerge into consciousness.
Yet in the human intellect there is an element which corresponds in some degree to the intuitive knowledge found in pure spirits. But it is intuition only in the wider sense of the word. When we affirm an object we are aware of the fact of affirming it. That awareness requires no concept or judgement whatsoever. It is direct and intuitive. And since the object of our knowledge is always the object of an affirmation, the object falls indirectly under this intuition. Therefore in human beings affirmation is the substitute for the intuition of pure spirits.