(1) the physical-chemical substructure,
(2) the biotic substructure,
(3) the sensitive or psychical substructure and finally
(4) the act structure.
The first three idionomies are the same as that of animals, however due to their character as substructures that support and anticipate the human act structure they are remarkably much more developed in several respects than the structure of any animal. Let us examine these in turn.
The first substructure of the human body is the physical idionomy qualified by the energetic aspect. It consists of the whole (inanimate) molecular structure of a human being. In and of itself this structure is not yet a human body, it is that only as it is bound to and lead by the higher structures. At death and with the process of decomposition of the body it is released from this encaptic relation to follow only the laws proper to it as a physical structure. To see the way the earlier substructures are intimately tied to the later ones we could consider the role of iodine within the normal functioning of the thyroid gland. While this gland has an idionomy that is biotically qualified, iodine has a physical-chemical qualification in respect of its own inner structure. The role of iodine is crucial for normal biotic growth, which in turn is foundational for emotional health. So when the thyroid gland is hyperactive, it causes excessive energy use, which can generate a faster heartbeat accompanied by a general unease and a heightened nervous sensitivity. Or in the case of hypothyroidism, often caused from iodine deficiency, in addition to the lethargy and slowing of the heart, one also discovers mental depression. This interweaving of iodine and the thyroid gland shows how the integrated functioning of the entire human being operates, without sacrificing the unique character of each substructure, and while resisting any reduction to the lowest idionomic level. So while maintaining its physical character iodine, in this example, nevertheless serves to support and enable the later idionomies and so has a special character that goes beyond what is found in animals.
The second idionomy is qualified by the biotic modal aspect. Here we include the role of living cells, tissues, organs and other biotically qualified structures. It also includes the so-called autonomic nervous system that influences the function of internal organs and all that governs the vegetative body processes such as breathing, heartbeat, and perspiration, in so far as they fall outside of the guidance of the psychic or later functions. We might also think here of the organs of the body, like the sense organs, the brain and nervous system. However it is important not to classify these organs as belonging exclusively to the biotic idionomy. This is because they all necessarily play their role in all four of the idionomies.
The third idionomy is the sensitive-emotional functions which, as instinctive, are for the most part outside our conscious control. They include the functions of the central nervous system and more particularly those of the senses, brain, spinal cord and glandular system as well as the muscle tissues. These allow us to perceive the world around us and experience emotions as they are taken up into the final idionomy they are no longer merely received, but also interpreted and named, reflected upon and shaped for human purposes. These three idionomies function as substructures since they can only be fully understood in their structural interlacement with, and disclosure by the final and highest structure, the act structure. It is only as bound to this structure that the preceding idionomies can be understood as typical structures of the human body. Here a crucial different is to be noticed in that the act structure is not qualified or led by a modal aspect and as such is undifferentiated. This leads us to the final and most characteristic level of our analysis, the human act structure.
The act structure is sometimes understood to comprise all the modal aspects higher than the psychical and so constitutes the arena where the subject functions of these modal aspects are realised. This would seem obvious from the preceding analysis of the three substructures and is also supported by the common division (made by Dooyeweerd) between normative and non-normative modal aspects marked at the dividing line of the logical aspect. Against this we can point to exercise, diet and desires as realities that require human realisation as positive, normal, norming features of human life. In addition it must be recognised that it is not only analytic intelligence that is crucial to setting and embodying normative responses, but also one’s aptitude, temperament, memory, and the reserve of one’s character and convictions. A second point is that the act life of the human person comes forth out of the heart as that which expresses itself in the functions and lives exclusively in them. At this point we also recognise the important sense in which humans are free in both thought and action. For although humans exist and function within the limits set by the laws of every aspect, the human self is not entirely the product of them or of any causal forces in creation. The human body is different to other entities we have investigated because unlike them because it lacks a qualifying or leading modal function. Instead it is the act structure that forms the highest qualifying structure and this is marked by its undifferentiated form. Dooyeweerd calls the act structure the “plastic expression of the human spirit” (Dooyeweerd 1942: Thesis XIX). ‘Plastic’ in the sense of having the greatest degree of flexibility to express itself in all possible differentiated structures. Here we arrive at the ‘open’ character of the human person which can only be understood from the perspective that as humans we know what it is to be called to bear responsibility, because we know the difference between good and evil.
This should lead us on to the central issue of religion, however we pause to consider the long tradition of thinking of the human person as body and soul.