John Locke

“ We are fitted for moral science, but only for probable interpretations of external nature. From whence it is obvious to conclude that, since our faculties are not fitted to penetrate into the internal fabric and real essences of bodies ; but yet plainly discover to us the being of a God and the knowledge of ourselves, enough to lead us into a full and clear discovery of our duty and great concernment ; it will become us, as rational creatures, to employ those faculties we have about what they are most adapted to, and follow the direction of nature, where it seems to point us out the way. ”

“ That which I have here to do, is to inquire, whether, if it be the readiest way to knowledge to begin with general maxims, and build upon them, it be yet a safe way to take the principles which are laid down in any other science as unquestionable truths ; and so receive them without examination, and adhere to them, without suffering them to be doubted of, because mathematicians have been so happy, or so fair, to use none but self-evident and undeniable. If this be so, I know not what may not pass for truth in morality, what may not be introduced and proved in natural philosophy. ”

“ In the knowledge of bodies, we must be content to glean what we can from particular experiments : since we cannot, from a discovery of their real essences, grasp at a time whole sheaves, and in bundles comprehend the nature and properties of whole species together. Where our inquiry is concerning co-existence, or repugnancy to co-exist, which by contemplation of our ideas we cannot discover ; there experience, observation, and natural history, must give us, by our senses and by retail, an insight into corporeal substances. ”

“ By which I think it is evident, that substances afford matter of very little general knowledge ; and the bare contemplation of their abstract ideas will carry us but a very little way in the search of truth and certainty. What, then, are we to do for the improvement of our knowledge in substantial beings ? Here we are to take a quite contrary course : the want of ideas of their real essences sends us from our own thoughts to the things themselves as they exist. ”

“ And if they be specific ideas of substances, we should endeavour also to make them as complete as we can, whereby I mean, that we should put together as many simple ideas as, being constantly observed to co-exist, may perfectly determine the species ; and each of those simple ideas which are the ingredients of our complex ones, should be clear and distinct in our minds. For it being evident that our knowledge cannot exceed our ideas ; as far as they are either imperfect, confused, or obscure, we cannot expect to have certain, perfect, or clear knowledge. ”

“ He that shall consider how little general maxims, precarious principles, and hypotheses laid down at pleasure, have promoted true knowledge, or helped to satisfy the inquiries of rational men after real improvements ; how little, I say, the setting out at that end has, for many ages together, advanced men’s progress, towards the knowledge of natural philosophy, will think we have reason to thank those who in this latter age have taken another course, and have trod out to us, though not an easier way to learned ignorance, yet a surer way to profitable knowledge. ”

“ For it is rational to conclude that our proper employment lies in those inquiries, and in that sort of knowledge which is most suited to our natural capacities, and carries in it our greatest interest, i.e. the condition of our eternal estate. Hence I think I may conclude that morality is the proper science and business of mankind in general, (who are both concerned and fitted to search out their summum bonum ;) ”

“ Knowledge is not got from maxims. It having been the common received opinion amongst men of letters, that maxims were the foundation of all knowledge ; and that the sciences were each of them built upon certain praecognita from whence the understanding was to take its rise, and by which it was to conduct itself in its inquiries into the matters belonging to that science, the beaten road of the Schools has been, to lay down in the beginning one or more general propositions, as foundations whereon to build the knowledge that was to be had of that subject. ”

“ And whatever we think of our parts or improvements in this part of the world, where knowledge and plenty seem to vie with each other ; yet to any one that will seriously reflect on it, I suppose it will appear past doubt, that, were the use of iron lost among us, we should in a few ages be unavoidably reduced to the wants and ignorance of the ancient savage Americans, whose natural endowments and provisions come no way short of those of the most flourishing and polite nations. ”

“ General and certain truths are only founded in the habitudes and relations of abstract ideas. A sagacious and methodical application of our thoughts. for the finding out these relations, is the only way to discover all that can be put with truth and certainty concerning them into general propositions. By what steps we are to proceed in these, is to be learned in the schools of the mathematicians, who, from very plain and easy beginnings, by gentle degrees, and a continued chain of reasonings, proceed to the discovery and demonstration of truths that appear at first sight beyond human capacity. ”

“ Our knowledge of substances is to be improved, not by contemplation of abstract ideas, but only by experience. In our search after the knowledge of substances, our want of ideas that are suitable to such a way of proceeding obliges us to a quite different method. ”

“ In the study of nature we must beware of hypotheses and wrong principles. I would not, therefore, be thought to disesteem or dissuade the study of nature. I readily agree the contemplation of his works gives us occasion to admire, revere, and glorify their Author : and, if rightly directed, may be of greater benefit to mankind than the monuments of exemplary charity that have at so great charge been raised by the founders of hospitals and almshouses. ”

“ Further, it is evident that it was not the influence of those maxims which are taken for principles in mathematics that hath led the masters of that science into those wonderful discoveries they have made. Let a man of good parts know all the maxims generally made use of in mathematics ever so perfectly, and contemplate their extent and consequences as much as he pleases, he will, by their assistance, I suppose, scarce ever come to know that the square of the hypothenuse in a right-angled triangle is equal to the squares of the two other sides. ”

“ For he that does not certainly know that any parcel of matter, with another parcel of matter joined to it, is bigger than either of them alone, will never be able to know it by the help of these two relative terms, whole and part, make of them what maxim you please. ”

“ Not that we may not, to explain any phenomena of nature, make use of any probable hypotheses whatsoever : hypotheses, if they are well made, are at least great helps to the memory, and often direct us to new discoveries. But my meaning is, that we should not take up any one too hastily (which the mind, that would always penetrate into the causes of things, and have principles to rest on, is very apt to do,) till we have very well examined particulars, and made several experiments, in that thing which we would explain by our hypothesis, and see whether it will agree to them all ”

“ But since the knowledge of the certainty of principles, as well as of all other truths, depends only upon the perception we have of the agreement or disagreement of our ideas, the way to improve our knowledge is not, I am sure, blindly, and with an implicit faith, to receive and swallow principles ”

“ Of what consequence the discovery of one natural body and its properties may be to human life the whole great continent of America is a convincing instance : whose ignorance in useful arts, and want of the greatest part of the conveniences of life, in a country that abounded with all sorts of natural plenty, I think may be attributed to their ignorance of what was to be found in a very ordinary, despicable stone ”

“ And he who, with Plato, shall place beatitude in the knowledge of God, will have his thoughts raised to other contemplations than those who look not beyond this spot of earth, and those perishing things which are to be had in it. ”

“ Let that principle of some of the old philosophers, That all is Matter, and that there is nothing else, be received for certain and indubitable, and it will be easy to be seen by the writings of some that have revived it again in our days, what consequences it will lead us into. ”

“ The knowledge of bodies we must get by our senses, warily employed in taking notice of their qualities and operations on one another : and what we hope to know of separate spirits in this world, we must, I think, expect only from revelation. ”

“ He that, with Archelaus, shall lay it down as a principle, that right and wrong, honest and dishonest, are defined only by laws, and not by nature, will have other measures of moral rectitude and pravity, than those who take it for granted that we are under obligations antecedent to all human constitutions. ”

“ We are able, I imagine, to reach very little general knowledge concerning the species of bodies and their several properties. Experiments and historical observations we may have, from which we may draw advantages of ease and health, and thereby increase our stock of conveniences for this life ”

“ They have been discovered by the thoughts otherwise applied : the mind had other objects, other views before it, far different from those maxims, when it first got the knowledge of such truths in mathematics, which men, well enough acquainted with those received axioms, but ignorant of their method who first made these demonstrations, can never sufficiently admire. And who knows what methods to enlarge our knowledge in other parts of science may hereafter be invented, answering that of algebra in mathematics, which so readily finds out the ideas of quantities to measure others by ”

“ All that I would say is, that we should not be too forwardly possessed with the opinion or expectation of knowledge, where it is not to be had, or by ways that will not attain to it : that we should not take doubtful systems for complete sciences ”

“ Nothing can be so dangerous as principles thus taken up without questioning or examination ; especially if they be such as concern morality, which influence men’s lives, and give a bias to all their actions. ”

“ We advance not here, as in the other, (where our abstract ideas are real as well as nominal essences,) by contemplating our ideas, and considering their relations and correspondences ; that helps us very little, for the reasons, that in another place we have at large set down. ”

“ This gave me the confidence to advance that conjecture, which I suggest, (chap. iii.) viz. that morality is capable of demonstration as well as mathematics. For the ideas that ethics are conversant about, being all real essences, and such as I imagine have a discoverable connexion and agreement one with another ; so far as we can find their habitudes and relations, so far we shall be possessed of certain, real, and general truths ”

“ Because the other properties of such bodies, depending not on these, but on that unknown real essence on which these also depend, we cannot by them discover the rest ; we can go no further than the simple ideas of our nominal essence will carry us, which is very little beyond themselves ”

“ This, I think, I may say, that if other ideas that are the real as well as nominal essences of their species, were pursued in the way familiar to mathematicians, they would carry our thoughts further, and with greater evidence and clearness than possibly we are apt to imagine. ”