In the last section, we described knowledge as the sort of information, i.e., of form or structure that enables a thing or system to behave ‘in the right way’, to accomplish goals, or to fulfill a purpose. Since also molecules (like the DNA) or machines, nay simple tools contain knowledge in this sense, we find that knowledge is neither depending on a brain or a nervous system nor on a biological substrate at all. However, knowledge seems to be depending on something else: on goals or purposes that can be accomplished by the respective knowledge.
One may object: A snow crystal as well behaves in a certain way because of its structure (i.e., its information) so that further water molecules are attached and make the crystal grow. But this behavior has no purpose, as the snow crystal itself has neither goal nor purpose – unless we believe in an intelligent designer who intended to embellish the world a little bit and to give children pleasure.
Snow crystals, clouds, stones, planets, stars are things begotten by natural causes, things that now are simply existing without having goals or purposes. Tools and machines, by contrast, have purposes, and living beings seem to have goals, at least the goals of survival and procreation, judging from their behaviors. Higher developed animals seem to have some further special goals, for example, to avoid pain.
The information contained in tools, machines, and other artifacts has extensively been discussed in Section 1.3. Their forms and structures result from the purposes they should fulfill, and these purposes result from human goals: from the general goals of survival, procreation, and the avoidance of sorrow and anguish, and the many special goals arising from them. In a similar way, the functionality of the forms and structures of our body and its components can be understood as resulting from the special purposes they fulfill, arising from the general goals of survival and procreation.
We can say about living beings in general: The functionality of their forms and structures answer the purposes of survival and procreation, and also procreation eventually answers the goal of survival as a species. The crucial question regarding the peculiar ‘teleological’ character of living things is therefore: Why – or from what – do living things get the goal of survival? Or is it wrong to speak of a goal here?
Let us first address the question of what life is [1]: From the view of physics, life is a rather improbable state which is characterized by homeostasis, i.e., by a self-regulated unstable, dynamic (flowing) equilibrium. This equilibrium is fragile, and its loss is the mostly irreversible backslide to the physically ‘normal’ state: the state of inanimate matter. The loss of equilibrium, of homeostasis is the end for a living thing. A living thing is a living thing only as long as it escapes death.
Thus, the ‘goal-directedness’ of living things is only the answer to another, reverse goal-directedness: the fact that death is the last ‘goal’ of all living things – falling back to the physically more probable state of lifelessness. The struggle to survive, at the same time, is a struggle against that which each living thing is inevitably heading for. This component of the goal-directedness of life – the tendency towards the decay of complexity, towards growing entropy – is not astonishing and in full accordance with our view of the physical world [2].
So we find that, together with life, also death came into the world. The permanent possibility of death is the ground on which living things have their goal and purpose in themselves: to survive, to maintain the improbable state of life, of homeostasis, to preserve one’s own structure (information) and to reproduce and to manifold it. So, the virtually teleological character of life is paradoxical in truth: The original purposelessness of natural processes appears to be split into the polarity of two opposite goals, to survive and to die, that are depending on each other – like the opposing electric charges of proton and electron in the atom.
Machines – they may be as complex and ‘intelligent’ as possible – have their purposes never in themselves but were made to fulfill human purposes [3]. Their activity is not truly their own but human activity – machines are the extended arm and now also the extended brain of humans. Stars, and also the Earth (vulcanism) show activity originating from themselves, but they don’t maintain homeostasis by active self-regulation, as living things do. Stars burn themselves as long as their energy lasts; their activity is not a struggle to survive, but by their activity they are steering towards their predetermined end as a black or white dwarf, a neutron star, or a black hole, depending on their mass.
Let us summarize the difference between living things and non-living natural objects, on one hand, and living things and artifacts, on the other hand: Living things have goal and purpose in themselves: to maintain and pass on the state of live and the structure/information being the basis for. Inanimate natural things have neither goals nor purposes, and artifacts have no purpose in themselves but answer human purposes.
Living things, so we said, are characterized by an internal dynamic equilibrium called homeostasis which depends on self-regulation. Let us now have a look at the structure which makes homeostasis possible: Living things exhibit a special structural feature: On one hand, they have a more or less firm outer casing – a membrane, cell wall, or epidermis – making them clearly bounded like a solid body. On the other hand, they are fluid in the interior – not only in the interior of cells, but also, e.g., in the interior of the alimentary canal and hemals in animals, or of the vascular tissue of plants. This fact is not as trivial as it may appear: In their structure, living things combine the merits of both aggregate phases: They are solid and fluid in one.
The fluid interior mainly of cells makes all the chemical processes possible that are constitutive for living things. The solid boundary clearly separates the interior of a living thing from the environment, which in the first place enables metabolism, i.e., the interchange of matter and energy between a living thing and its environment. This permanent interchange, however, has the effect that changes in the environment, e.g., of temperature or of substance concentration, results in changes in the interior of a living thing. The living thing, however, has to maintain its homeostasis, its internal equilibrium despite such changes. Its self-regulation is required to keep internal fluctuations within certain limits. A great change in the environment may therefore result in a counter reaction in the living thing.
We can therefore say: The interior of a living thing is sensitive to environmental changes. We can also say: The internal state of a living thing mirrors the environment in a way – but not like a common mirror which does not change itself by mirroring a change. A living thing’s internal state mirrors a change in its environment by changing itself.
This, of course, would be trivial if the change in the interior would simply follow the change in the exterior – a stone as well becomes warmer internally when the sun shines on it. But when the temperature becomes too high in a living thing’s interior, then the self-regulation counteracts, heat is anyway discharged in order to maintain homeostasis; otherwise the living thing dies. That is, the change in the interior of a living thing is not only the result of external changes, but is determined by the self-regulation for maintaining homeostasis.
Indeed, many a technical system, e.g., a heating with thermostat is capable of some self-regulation. But here, setpoint and limits are determined by humans. Therefore, technical systems are not really self-regulated in the full sense. We will consider this important difference between living and technical systems in a later section. Let us summarize: Living things mirror their environment in their interior, but they do so in an active and idiosyncratic manner.
The figure shows mineral dendrites of manganese oxide, found on the surface of limestone from Bavaria – an example of growth and ramification in inorganic matter (photo by Tamás Viscek in Philip Ball, The Self-made Tapestry, Oxford University Press 1999, p. 110).