The History of Biological Theories

WhewelPs belief in the continual progress of science had a decisive influence on later historians. Very soon it was not thought necessary to demonstrate this progress by any process of critical analysis ; it was treated as a self- evident fact. This was very disastrous for the writing of scientific history ; for if science is continually advancing the whole of its past is included in its present. All that the historian can do is to discuss its former errors; and this purely negative task is of little interest.

Some historians gave other arguments in defence of their subject. Cuvier gives a very clear summary of these in the introduction to his history. The study of the history of science is indispensable, he says, because (i) scientific theories rest upon facts, and it is the task of the historian to collect those facts ; (2) the writing of history makes a repetition of work that has already been done impossible ; (3) it helps to suggest new ideas, and so increases know- ledge and inculcates the true scientific spirit.

History has not, in fact, played the part in teaching which is here assigned to it. No historical work has exerted any considerable influence on the views most widely held by modern investigators. The theory that science is an objective study, and independent of the individual worker, led to the assumption that each investi- gator either adds to the structure or does it harm; and it was the task of the historical writer to determine the part played by each scientist in the building of the whole fabric. Some have done more, others less ; hence we talk of an investigator's 'services' to science. We may open any modern book we care to choose, in which the develop- ment of a scientific investigation is described, and we shall find that the sole object of such a work is to give an account of the services of individual workers. But who can truly estimate the services of another ? At the most, only another discoverer who can judge his predecessor's work by his own. The historian who is simply recording discoveries has no right to evaluate services. Hence he is made to feel that his work lacks all originality, that it lacks the true scientific spirit. Specialists look upon his work as popular. Even when exact science was at the zenith of its philo- sophical reputation historical works dealing with it were rare. Histories of biology are merely lists of Darwin's 'forerunners', or historical introductions to various mono- graphs. This represents a curious type of historical writing it is really only make-believe history. The investigator, pre-occupied with some idea, seeks to explain his views to investigators who disagree with him. After considering the ideas of the living he passes to those of the dead, sifting out those theories which were akin to his own, or those opposed to his ; he points out where these were right or where they were wrong, and in this way clarifies his own ideas. He makes a chronological list of his pre- decessors, and so produces a history.

Such works of which Sachs' History of Botany and Driesch's History and Theory of Vitalism are good examples provide good foundations for the true historical writer; for when any investigator has formed an independent judgement about a problem his criticisms of other solutions of the same problem are bound to be illuminating. These works cannot be called historical works, however. All that they attempt to do is to show whether certain ideas were right or wrong. The true historian is not concerned with the correctness of ideas ; he must regard them as events, as plastic realities.

In recent years biologists have paid much more atten- tion to historical research. Having reached the end of a great creative period, we are looking back and endeavour- ing to see the whole story in perspective, to form a picture of what we have really lived through. Up to the present, however, such histories have been too timid. There has been no attempt to depart from the old well-beaten track which has been followed so long in the writing of biological history. They teach us nothing that could not be learnt just as well from a study of the science itself. Burckhardt's essay, Biology and Biological History (1909), forms an honourable exception to this rule. This author shows very clearly that the ideas underlying biological history are quite different from the ideas underlying biology. He affirms that the former must develop methods of its own, and expresses a hope that in the future the history of biology will, from the philosophical point of view, be as important as any other branch of history.

In the preceding chapters we have attempted to treat the history of biology from a new point of view. This has often provided the opportunity for introducing broad general principles which may perhaps be important in all historical writings. We may now, having reached the end of our task, discuss, in relation to what we have discovered, the true aim of all historical writing. We read everywhere that science consists in a search for truth. The historian who wrote in the philosophical manner about the evolution of science also began from this maxim. Following it, he tried to picture science as something continually advancing towards truth and con- tinually overcoming error. Many, of course, are striving after some ideal of 'truth' many more, perhaps, than we at first realize. But this word 'truth' has more than one meaning. It is often affirmed that natural science is seek- ing 'truth', as opposed to 'error 5 ; yet it is not this very abstract and logical truth which is the real driving power behind scientific research. History teaches us that the truth, which is the mere negation of error, exerts no very

strong influence over the minds of men. Directly Darwin published his ideas every possible argument was brought against them. Haeckel had to meet very severe criticism on the very threshold of his literary and scientific career, but all this criticism produced very little effect. The founders of Darwinism, however, were not posing as mere correctors of errors, as improvers of the old ideas ; they were active protagonists of new ones. Kant and his philosophical work afford an excellent illustration of this truth. IJis work is really nothing but an essay in criticism, an essay in logic. This did not lead, however, to any still sharper criticism (i.e. differentiation of truth and error) from his followers. He became famous as the discoverer of the a priori.

The same is true of the efforts of individual investigators. In their introductions, of course, they affirm that they have undertaken the investigation in the interests of truth. They have set out 'thoroughly to examine the doctrine of the individuality of the chromosomes', 'to ascertain the meaning of the mesenchyme', or 'the function of the organ of hearing'. Usually, however, work dealing with such questions is actually begun because of a very suc- cessful preparation, or a chance observation made on material which happens to be available. The investigator is more often attracted by a new fact than by any abstract truth. This is true even when he formulates a new theory. His interest in it is first aroused because he seems to be discovering a new truth, and not because it affords a better explanation of facts already known. For even theories appear at first as fresh green boughs on the tree of know- ledge ; they become dry and brittle when they no longer represent new truths, but merely express logical ones.

The word 'truth' is very often used to denote some actual experience or fact, something of which we have direct knowledge, and which is not only true, but is concrete, having a definite form. The blue sky, Darwin's theory, the division of labour in the animal world all represent such realities. The history of biology, like every other intellectual pursuit, is the study of these realities. The task of the biological historian is not to discover logical truths, but those living ideas which shall guide investi- gators, which shall force research workers to attack definite problems, to review their facts from a certain fixed point of view, and to believe in definite theories. This may lead an investigator to a distorted conception of reality, but it is what we mean when we say of him 'he has an idea'. An idea is something original; it is not just learnt, nor is it arrived at by any conscious process whatsoever. An idea must underly every scientific activity ; hence ideas are the more fundamental, and so the greater, realities.

The theories of Darwin, of Wallace, and of Erasmus Darwin were ideas of this type. They were not hypotheses which were acquired or suddenly made accessible; nor were they 'points of view' ; but were direct convictions which gradually arose in the minds of their discoverers. If a student discusses Darwin's fundamental ideas, or a writer says that he believes in Darwin, these people are not really expressing 'ideas' of this type. To some readers it will seem strange that we accentuate so strongly the fact that science is dominated by ideas which are original products of the human spirit. Modern theories about scientific activity do not, however, recognize the existence of any such inspirational ideas. When the evolution of a theory is discussed we speak of 'ideas thrown out', of hypotheses, of proved facts. But in all this we are only describing the method ; we learn a great deal about the care and industry with which the scientist has investigated his problem. But we completely ignore the punctum saliens ; to 'throw out' a suggestion, we must first of all formulate that suggestion.

We often read, it is true, that the suggestion was made by some previous worker, but the proof added later by a subsequent investigator ; it is to the latter that the credit of making a new discovery then belongs. Experience shows us that truths which are eventually confirmed are not stumbled upon in this haphazard manner. Should such a thing happen, the discoverer would simply not believe in his discovery. It would seem to him as valueless as is a Latin word to a man who knows no Latin. If he does believe in its truth, it represents an idea, and it is the task of the historian to show how he conceived that idea.

The difference between science and the presentation of scientific history is like the difference between nature and natural science. The first is fundamental ; the second repre- sents our views of the nature of that which is fundamental. Modern science is not alive to this difference. Material- ists and idealists alike seem to consider that Nature is identical with our picture of Nature ; the former declare that it is Nature which is real, the latter that it is our picture which is real. We will not go any further into the philosophical aspects of this problem ; there is, however, in practice, a difference between the object and the know- ing of that object. Suppose we declare that animals, plants, and cells are merely ideas. We are all aware that these ideas relate to something which is more material than are our opinions, hypotheses, and assertions. Suppose we assert that a plant is a structure composed of cells. There is underlying this assertion some reality, the nature of which is not exhausted by the assertion that 'the plant is composed of cells'. The artist will give another defini- tion, and the chemist still another, of the same plant. Even science defines the same plant differently at different periods. Our conceptions, then, are mere shadows, mere reflections of reality. Even when they are true, they only penetrate, to a greater or lesser extent, into the actual nature of the reality. Although it is not admitted, this is also true of history and of historical writing. Historians assume that all that survives from the work of each scientist is the work incorporated in and accepted by the science of their time. It is this, for example, which leads to the endeavour to prove that Darwinism is still believed

in ; it is for this reason that the 'decline' of Darwinism sounds so ominous in our ears. This is why we are only interested in earlier investigators if we consider that they discovered new 'truths'. There is a certain greatness about this conception to which Nietzsche has given expression : 'Every great man has a retrospective influence. Our reading of the whole of history is revised for his sake, and hundreds of the secrets of the past crawl out from their hiding-places out into the sun.

*We cannot possibly foretell what minor incident will form a part of history in the time to come. The past is still largely undis- covered. It requires so many of these retrospective influences.' x If this is true, then the past does not coincide with our picture of it, nor with the picture of it which will be painted by our descendants ; it does not coincide with the picture of it formed by any man or at any epoch it is quite independent of all this.

What we learn to-day about Darwin or Cuvier or Newton does not make those investigators live beyond the grave. All that lives is our conceptions of them ; these we build up from the documents which those investigators left behind them. Suppose there had been no such documents. Their immortality would not have been diminished in any way, but our conception of it would have suffered. Or is it perhaps true that our knowledge of an object does influence that object in some way quite unknown to us ?

We all agree that to proclaim a truth is one thing, but to help it to gain general acceptance is quite a different task. We realize that science recognizes many theories which are not 'truths' ; that, on the other hand, there are many truths which mankind, including the scientist, refuses to accept. This is true, even of historians they, too, only accept those truths which have won general recognition. They do not trouble very much about the pioneers who failed to obtain recognition, and who suffered in their conflict with society, though they often ask how we may avoid similar occurrences in the future. They feel them- selves competent to criticize general conditions, or to discuss definite persons. But there is one thing they never do: they never show that unrecognized truths are always in existence, side by side with those which have won acknowledgement; nor do they realize that the historian must take cognizance of both groups. Probably one of the most fundamental characteristics of an original idea is that it 'will out', that it strives for recognition ; its bearer is driven to declare it, to fight for it yea, only too often, to suffer for it.

In these moving words Lenau has given voice to the passionate desire of his generation for truth. Can we doubt that the spirits of our pioneers are still troubled with this same haste, this restlessness, this weariness ? Thousands of ideas present themselves and fight for recognition. Most of them are buried in the distracted souls of a listening world. The historian must not shut his eyes to these facts. He must search for truth everywhere, not only there, where it has received public recognition, but wherever mankind is thinking. He must not forget that even to-day, and even in the world of science, those glorious words which were spoken two thousand years ago are still applicable: 'A kingdom not of this world.' By the play of circum- stances an idea is sometimes promoted, sometimes sup- pressed. An historian must not allow this to influence him ; his task is to recognize ideas, not to paint the successes

of this world. He must recognize every new thought, even if, in the clash of ideas, it vanishes and leaves no apparent trace. It is still a fact for the writer of history, for it is a truth, and belongs therefore to that world of truths in which the historian lives, moves, and has his being. He must recognize the truth himself; he must not wait until it is forced upon him from outside by the pressure of public opinion. Only too often he has cause to call to mind the words of Feuchtersleben:

Nothing, cry they, all unknowing, Comes of labour, naught to see ! All this time is Greatness growing Silently. Manifest, yet still un-noted 'Mid the world's confusing cry, She, to lowliness devoted, Passes by. The more earnestly the historian strives to pick out this 'humble greatness' as it passes, to recognize it amidst the whirl of conflicting opinions, the more nearly does he deserve the title of Discoverer, Philosopher, Great Man. N.B. The translator is indebted to her colleague, Miss F. Gibbons, for her kind help with the translation of the foregoing two lyrics.

Burnett, J., lord Monboddo, man and animal creation, 158; theories, 2. Darwin, Charles Robert, 12-31 el passim (and see Contents); his son, De la Mettrie, J. C., likeness of man to animal creation, 1 58. Neumayer and Cope, 276; Darwinian palaeontology, 217; organic evolu- tion, 214; variations and mutations, St. Basil of Cappadocia, creation, i. St. Clement, creation, i. St. Gregory of Nyssa, creation, i. Whewell, W., botany and zoology, 288; and Darwin, 13; Inductive Sciences,