John Locke and the scientific revolution: a study of the essay concerning human understanding in relation to seventeenth century science

Abstract

This work aims to set Locke's Essay Concerning Human Understanding in the context of the scientific revolution of the seventeenth century. It does this by showing that the problem of the extent of human understanding to which Locke tried to find an answer was an issue which itself arose out of developments in the sciences in the seventeenth century, and that Locke's answer was itself indebted in a variety of ways to the work of the scientists. Locke's Essay, therefore, cannot be appreciated fully unless its background is also understood.
There is, therefore, a dual aspect to the programme: the scientific background, and the Essay itself. For this reason the thesis is divided into two parts. Part One traces the course of a series of scientific and epistemological issues in the scientific revolution, and shows how scientists answered the problems, sometimes rightly, sometimes wrongly, but, nearly always within the confines of natural philosophy. Part Two is concerned with the intimate link between Locke's answers and the problems faced and the method practised by the scientists. It emerges that not only is much of the content of Locke's answer indebted to the scientific revolution, but also that much of the form of his argument borrows from the new science. The two parts of the work are preceded by an Introduction.
Part One has seven chapters. Each chapter is concerned with a particular period or a key figure in the scientific revolution. A common theme is the outlook of the various scientists to the possibility of science achieving knowledge, as opposed to either belief, or its function being only to 'save the appearances', to be, that is, merely a useful calculating device. Other aspects of the thought of the scientists are also considered, but the strong central theme is whether or not they believed that man could obtain knowledge.
Chapter One is about a group I call the Neoplatonists. These include Copernicus, Kepler, and the Englishman John Dee. With Copernicus and Kepler I have concentrated particularly on their attitude towards the truth of the heliocentric system. I have used this example to draw out their attitude towards the possibility of achieving truth in the science of astronomy, and I have contrasted their attitude with that of Osiander. Dee's general attitude to science and knowledge, as revealed in his Preface to the first English edition of Euclid's Elements, is shown to have important likenesses with the outlook of Copernicus and Kepler.
In Chapter Two I consider the general scientific outlook of Galileo, beginning with his acceptance of the heliocentric theory, and relating his views on astronomy to his larger conception of the nature of science and the possibility of achieving truth in the sciences. Galileo, like the earlier Neoplatonists, emerges as a man who saw the natural sciences as achieving a degree of certainty which is in fact unjustified; it is an attitude which stands in marked contrast to most pre-Renaissance thinkers.
Chapter III looks at the nature and limits of science as conceived by Descartes. The paradigm of mathematical certainty which Descartes propounded is assessed, and the limitations of the programme which Descartes mapped out are identified. The chapter also includes a section
on Rohault, a Cartesian who did not follow Descartes in all his recommendations, and who was influential in science in the latter part of the century.
In Chapter IV we return to the work of Francis Bacon whose influence over the development of the English conception of the right method to be pursued by scientists was central. Bacon laid down the general empirical approach to nature which was to become the dominant procedure of the scientists of the Royal Society; but Bacon never set the method in a general epistemological context. The general approach of Englishmen in the period from Bacon to Newton towards the proper extent and nature of the scientific enterprise is examined in Chapter V. Generally, there were two rather different approaches. Some men, like Sir Kenelm Digby and Robert Hooke, expected certainty from science in the true Baconian fashion. Others, like Joseph Glanvill, had no such high expectations. The position, therefore, remained uncertain as to the possible extent of human knowledge.
In Chapter VI we look at the approach to this problem of one of the most important thinkers of seventeenth century England, Robert Boyle. Boyle, we discover, was not so optimistic in outlook as the true Baconians, for he did not expect science to give absolute certainty. Indeed he saw good reason why it could never do so. But he did believe that science could and did achieve Borne form of knowledge about the physical world.
Similar attitudes towards the scope of science were exhibited by Isaac Newton whose views on the possibility of knowledge are considered in Chapter VII. Newton did not expect science to be able to go much beyond experience, but he did hold that there was a correct method to be followed in scientific.procedure which could and did lead to knowledge. This knowledge might have to be revised in the light of experience, but it should not be rejected out of hand simply because that possibility existed.
In the second part of this work I have attempted to show how John Locke's Essay was a very real attempt to answer the question which had arisen largely as a result of the new science, namely: What was the extent and the limits of human knowledge? We see also how right Locke was to characterize himself as an underlabourer of the new science, for not only was he concerned to clarify issues which scientists had raised about the nature and limits of knowledge, but he also took Over many of their presuppositions. Further, Locke's method of approach to his problem is one which itself borrows much from the method of contemporary science.
In Chapter VIII we look at Lockets own scientific background to discover the extent of Lockets acquaintance with the new science. Locke emerges as a man who was well established in at least two important branches of contemporary science, medicine and chemistry, and familiar with most others. He was, therefore, eminently well suited to try to relate science to epistemological issues.
In Chapter IX we turn to the first Book of Locke's Essay in which we find that Locke's argument is one that takes a great deal from the method of contemporary science. The theory of innate ideas is treated by Locke as an hypothesis which is to be rejected as not being substantiated by the empirical data.
Locke's positive thesis, that the mind is furnished with ideas which are all drawn from experience, is considered in Chapter X. Locke's arguments to show that certain of our ideas are the result of experiences are found to be lacking. Thus we find that Locke fails to give an adequate account of such central notions to the scientific revolution as those either of causation or of material object. But the effect of Lockets programme is to emphasise the importance of the contingent and the empirical for man's knowledge.
Chapter XI examines Locke's treatment of the notion of a material object. I consider the reasons why he is led to postulate the existence of material substance, his arguments to show that we cannot know the essences of physical objects, and the implications which these points have for the possibility of achieving knowledge in the sciences.
Finally, in Chapter XII, we turn to Locke's positive answers to the question of the limit and extent of human knowledge. We find that although Lockets definition of knowledge is excessively narrow, the general points which he has to make about the possible extent of knowledge are substantial, and substantially correct. Furthermore, they reflect very accurately the views expressed, usually only with regard to science, by Locke's contemporaries such as Boyle and Newton. Fundamentally, Locke's message was that whilst man should not have expectations about the degree of certainty which science could give which went beyond the contingent and the empirical, it was, nevertheless, right to have such expectations: there was indeed a middle course between the two evils of scepticism and dogmatism.