Every empirical problem may be studied in two different ways. We may begin with the naïve unbiassed analysis of the facts and then proceed to logical and theoretical discussion. Or we may begin with the discussion of logical and epistemological possibilities and illustrate them with facts later on. The second method may be more “philosophical” than the first; the first method, nevertheless, is more natural psychologically, and, as it is the method applied by the author in his own scientific life, we shall accept it in this book, i.e. we will begin with the facts and will end with the philosophical discussion.
This implies that the first part of this book, the biological one in the proper sense, can be written from the point of view of what is generally called a naïve realism. We start from the thesis that there is or exists something in space, which we call nature, and of which one side is living or organic, whilst the other side is not. And we try to find out some order in the midst of the organic side of nature. This, at least, is to be our first task.
Practically, all of us know what a living being is, and therefore it is not necessary to formulate a definition of life, which, at the beginning of our studies, would be either provisional and incomplete, or else dogmatic. In some respects, indeed, a definition should rather be the end of a science than its opening.
Biology, the science of living nature, is the highest of all natural sciences, for it embraces as its final object the actions of man, at least in so far as actions also are phenomena observable on living bodies.
But biology is also the most difficult of all natural sciences, not only from the complexity of the phenomena which it studies, but in particular for another reason which is seldom properly emphasised, and therefore will well repay us for a few words devoted to it.
The experimenter in the inorganic fields of nature is not hampered by the specificity of composite objects: he “makes” all the combinations he wants. He is always able to have at his disposal red rays of a desired wave-length when and where he wants, or to have, at a given time and place, the precise amount of any organic compound which he wishes to examine. And he forces electricity and electro-magnetism to obey his will, at least with regard to space, time, and intensity of their appearance.
The biologist is not able to “make” specific forms of life, as the physicist has made red rays, or as the chemist has made a certain compound of carbon. The biologist is almost always in that strange plight in which the physicist would be if he always had to go to volcanoes in order to study the conductivity of heat, or if he had to wait for thunder-storms in order to study electricity. The biologist is dependent on the specificity of living objects as they occur in nature.
A few instances may show you what great inconveniences may hence arise to impede practical biological research. We later on shall have to deal with experiments on very young embryos: parts of the germ will have to be destroyed in order to study what will happen with the rest. Now, almost all germs are surrounded by a membrane; this membrane has to be detached before any operation is possible. But what are we to do if it is not possible to remove the membrane without killing the embryo? Or what if, as for instance in many marine animals, the membrane may be removed but the germs are killed by contact with sea-water? In both cases no experiments at all will be possible on a sort of germ which otherwise, for some special circumstances of its organisation, might have given results of importance. These results become impossible for only a practical and very secondary reason; but enough: they are impossible, and they might have thrown light on problems which now must remain problems. Quite the same thing may occur in experiments on physiology proper or functional physiology: one kind of animals survives the operation, the other kind does not, and therefore, for merely extrinsic reasons, the investigations have to be restricted to the first, though the second might have given more important results. And thus the biological experimenter always finds himself in a sort of dependence on his subjects, which can hardly be called pleasant. To a great extent the comparatively slow advance of biological sciences is due to this very fact: the unalterable specific nature of biological material.
But there is still another feature of biology dependent on the same fact. If a science is tied down to specific objects in every path it takes, it first, of course, has to know all about those objects, and that requires nothing else but plain description. We now understand why pure description, in the most simple sense of the word, takes up such an enormous part of every textbook of biological science. It is not only morphology, the science of form, that is most actively concerned with description; physiology also, in its present state, is pure description of what the functions of the different parts of the body of animals and plants actually are, at least for about nine-tenths of its range. It seems to me important to press this point very emphatically, since we often hear that physiology is from the very beginning a much higher sort of knowledge than morphology, inasmuch as it is rational. That is not at all true of the beginning of physiology: what the functions of the liver or of the root are has simply to be described just as the organisation of the brain or of the leaf, and it makes no difference logically that one species of description has to use the experimental method, while the other has not. The experiment, which only discovers what happens here or what happens there, possesses no kind of logical superiority over pure description at all.
Natural sciences cannot originate before the given phenomena of nature have been investigated, in at least a superficial and provisional manner, by and for the practical needs of man. But as soon as true science begins in any limited field, dealing, let us say, with animals or with minerals, it at once finds itself confronted by two very different kinds of problems.
In any branch of knowledge which practical necessities have separated from others, and which science now tries to study methodically, there occur general sequences in phenomena, general orders of events. This uniformity is revealed only gradually, but as soon as it has shown itself, even in the least degree, the investigator seizes upon it. He now devotes himself chiefly, or even exclusively, to the generalities in the sequences of all changes. He is convinced that there must be a sort of most general and at the same time of most universal connection about all occurrences. This most universal connection has to be found out; at least it will be the ideal that always will accompany the inquiring mind during its researches. The “law of nature” is the ideal I am speaking about, an ideal which is nothing less than one of the postulates of the possibility of science at all.
Using for our purposes a word which has been already introduced into terminology by the philosopher Windelband,1 we shall call that part of every branch of natural sciences which regards the establishment of a law of nature as its ideal, “nomothetic”, i.e. “law-giving”.
But while every natural science has its nomothetic side, it also has another half of a very different kind. This second half of every natural science does not care for the same general, the same universal, which is shown to us in every event in a different and specified kind: it is diversity, it is specification, that constitutes the subject of its interest. Its aim is to find a sufficient reason for the types of diversities, for the types of specifications. So in chemistry there has been found a systematic order in the long series of the compounds and of the elements; crystallography also has its different systems of crystals, and so on.
We have already employed the word by which we shall designate this second half of every natural science: it is the “systematic” side of science.
Nomothetic work on the one side and systematics on the other do, in fact, appear in every natural science, and besides them there are no other main parts. But “science” as a whole stands apart from another aspect of reality which is called “history”. History deals with particulars, with particular events at a given time and a given place, whilst science always abstracts from the particular, even in its systematic half.
Turning now to a sort of short outline of what is to be discussed in the whole of this book, it seems clear, without further analysis, that biology as a science has its nomothetic and its systematic part also; respiration and assimilation, for instance, have proved to be types of natural laws among living phenomena, and that there is a “system” of animals and plants is too commonly known to require further explanation here. Therefore we might study firs’ biological laws, and after that biological systematics, and in the third place perhaps biological history. But that would hardly correspond to the philosophical aims of our lectures: our chief object is not biology as a regular science, as treated in text-books and in ordinary university lectures; our chief object is the Philosophy of the Organism, as aided and supported by scientific biology. Therefore a general acquaintance with biology must be assumed in these lectures, and the biological materials must be arranged according to their bearing on further, that is on philosophical, analysis.
That will be done, not, of course, to the extent of my regarding every one of my readers as a competent biologist; on the contrary, I shall explain most fully all points of biology proper, and even of the most simple and descriptive kind of biology, which serve as bases for philosophical analysis. But I shall do so only if they indeed do serve as such bases. All our biology will be not for its own sake, but for the sake of philosophy.
Whilst regarding the whole of the biological material with such aims, it seems to me best to arrange the properly scientific material which is to be the basis of my discussions, not along the lines which biology as an independent science would select, but to start from the three different kinds of fundamental phenomena which living bodies offer to investigation, and to attach all systematics exclusively to one of them. For there will not be very much for philosophy to learn from biological systematics at present.
Life is unknown to us except in association with individual bodies: we only know living individuals and call them organisms. It is the final object of all biology to tell us what it ultimately means to say that a body is “living”, and in what sorts of relation body and life stand one to the other.
But at present it is enough to understand the terms “individual body” and “living” in the ordinary and popular sense.
Regarding living bodies in this unpretentious manner, and recollecting what the principal characters are of all bodies we know as living ones, we easily find that there are three features which are never wanting wherever life in bodies occurs. All living bodies are specific as to form—they “have” a specific form, as we are accustomed to say. All living bodies also exhibit metabolism; that is to say, they stand in a relation of interchange of materials with the surrounding medium, they take in and give out materials, but their form can remain unchanged during these processes. And, in the last place, we can say that all living bodies move; though this faculty is more commonly known among animals only, even elementary science teaches the student that it also belongs to plants.
Therefore we may ask for “laws of nature” in biology about form, about metabolism, and about movements. In fact, it is according to this scheme that we shall arrange the materials of the biological part of this book, though, as we cannot regard the three divisions as equally important in their bearing on our ultimate purposes, we shall not treat them quite on equal terms. It will appear that, at least in the present state of science, the problems of organic form and of organic movement have come into much closer relation to philosophical analysis than have most of the empirical data on metabolism.
It is form particularly which can be said to occupy the very centre of biological interest; at least it furnishes the foundation of all biology. Therefore we shall begin our scientific studies with a full and thorough analysis of form. The science of living forms, later on, will afford us a key to study metabolism proper with the greatest advantage for our philosophical aims, and therefore the physiology of what is usually called the vegetative functions will be to us a sort of appendix to our chapters on form; only the theory of a problematic” living substance” and of assimilation in the most general meaning of the word will be reserved for the philosophical part—for very good reasons, as I hope to show. But our chapters on the living forms will have yet another appendix besides the survey of the physiology of metabolism. Biological systematics almost wholly rests on form, on “morphology”; and what hitherto has been done on the metabolical side of its problems consists of a few fragments, which are far from being an equivalent to the morphological system; though, of course, it must be granted that, logically, systematics, in our general meaning of the word, as the sum of problems about the typically different and the specific, may be studied on the basis of each one of the principal characteristics of living bodies, not only on that of their forms. Therefore, systematics is to be the second appendix to the chief part of our studies in morphology; and systematics, in its turn, will later on lead us to a short sketch of the historical side of biology, i.e., to the theory of evolution in its different forms.
Goethe once said, that even in so-called facts there is more “theory” than is usually granted; he apparently was thinking of what might be called the ultimate or the typical facts in science. It is with such typical or ultimate facts, which always relate to generalities, that we must become acquainted if our future philosophy is to be of profit to us.
Our first discussion, it was said, is to be devoted wholly to organic forms. What then are the essentials of a living form, as commonly understood even without a special study of biology?
Living bodies are not simple geometrical forms, not, like crystals, merely a typical arrangement of surfaces in space, to be reduced theoretically to an arrangement of elemental particles. Living bodies are typically combined forms; that is to say, they consist of simpler parts of different characters, which have a special arrangement with regard to one another; these parts have a typical form of their own and may again be combinations of more simple different parts. But besides that, living bodies have not always the same typically combined form during the whole of their life: they become more complicated as they grow older; they all begin from one starting-point, which has little form at all, viz., the egg. So the living form may be called a “genetic form”, or a form considered as a process, and therefore morphogenesis is the proper and adequate term for the science which deals with the laws of organic forms in general; or, if you prefer not to use the same word both for a science and for the subjects of that science, the physiology of morphogenesis.
Now, there are different branches of the physiology of morphogenesis or physiology of form. We may study, and indeed we at first snail study, what are the laws of the morphogenetic processes leading from the egg to the adult: that may be properly called physiology of development. But living forms are not only able to originate in one unchangeable way: they may restore themselves, if disturbed, and thus we get the physiology of restoration or restitution as a second branch of the science of morphogenesis. We shall draw very important data, some of the foundations indeed of our philosophical discussions, from the study of such restitutions. Besides that, it is to them that our survey of the problems of the physiology of metabolism is to be appended.
Living forms not only originate from the egg and are able to restore themselves, they also may give origin to other forms, guaranteeing in this way the continuity of life. The physiology of heredity therefore appears as the counterpart to those branches of the physiology of form which deal with individual form and its restitutions. And our discussion on heredity may be followed by our second appendix to this chief section on form, an appendix regarding the outlines of systematics and evolution.
Theoretical considerations on biology generally start, or, at least, used to start, from the evolution theory, discussing all other problems of the physiology of form by the way only, as things of secondary importance. You see from our programme, that we shall go just the opposite way: evolution will come last of all, and will be treated shortly; but the morphogenesis of the individual will be treated very fully and very carefully indeed.
Why then this deviation from what is the common practice? Because we do not know very much about evolution at all; because in this field we are just at the very beginning of what deserves the name of exact knowledge. But concerning individual morphogenesis we really know, even at present, if not very much, at least something, and that we know in a fairly exact form, aided by the results of experiments.
And it will not be without its reward, if we restrict our aims in such a manner, if we prefer to deal more fully with a series of problems which may seem at the first glance to be of less interest than others. After a few chapters we shall find already that we may decide one very important question about life merely by an analysis of individual form production, and without any regard to problematic and doubtful parts of biology: that we may decide the question, whether “life” is only a combination of chemical and physical events, or whether it has its elemental laws, laws of its own.
But to prepare the road that is to lead to such results, we first have to restrict our aims once more, and therefore the next chapter of this book, which eventually is to touch almost every concept of philosophy proper, will begin with the pure description of the individual development of the common sea-urchin.
Geschichte und Naturwissenschaft, several editions.