# Adolphe Quetelet

Lambert Adolphe Jacques Quetelet (or Quételet) (22 February 1796 – 17 February 1874) was a Belgian astronomer, mathematician, statistician and sociologist. He founded and directed the Brussels Observatory and was perpetual secretary of the Royal Academy of Brussels. Quetelet was influential in introducing statistical methods to the social sciences.

## Quotes

* It has seemed to me that the theory (calcul) of probabilities ought to serve as the basis for the study of all the sciences, and particularly of the sciences of observation.
** Instructions populaires sur le calcul des probability (1825) English translation by R. Beamish (1839)
* The great body of population dynamics, like those of the motion of the celestial bodies, can be solved—and what is most remarkable, there is a surprising analogy between the formulas employed in these calculations. I believe that I have achieved to some extent what I have long said about the possibility of founding a social mechanics on the model established by celestial mechanics—to formulate the motions of the social body in accordance with those of celestial bodies, and to find there again the same properties and laws of conservation.
** Astronomie élémentaire? (1834) as quoted by Theodore M. Porter, "From Quetelet to Maxwell: Social Statistics and the Origin of Statistical Physics" in The Natural Sciences and the Social Sciences: Some Critical and Historical Perspectives (2013) ed., I. Bernard Cohen
* This great body (the social body) subsists by virtue of conservative principles, as does everything which has proceeded from the hands of the Almighty... When we think we have reached the highest point of the scale we find laws as fixed as those which govern the heavenly bodies: we turn to the phenomena of physics, where the free will of man is entirely effaced, so that the work of the Creator may predominate without hindrance. The collection of these laws, which exist independently of time and of the caprices of man, form a separate science, which I have considered myself entitled to name social physics.
** As quoted from his Letters, in Hankins, Frank Hamilton. 1908. "Adolphe Quetelet as Statistician." Columbia University, Longmans, Green & Company, agents, Chapter IV. p. 99
* Little by little his conversation, always instructive and animated, gave a special direction to my tastes, which would have led me by preference towards letters. I resolved to complete my scientific studies and followed the courses in advanced mathematics given by M. [Jean Guillaume] Gamier. It was at the same time agreed by us that, in order to relieve him in his work, I should give some of the other courses with which he was charged. I thus found myself his pupil and his colleague.
** "Notice sur J.G. Garnier," Annuaire de l'acad. roy. de Brux. (1841) Vol. vii pp. 200-201 as quoted in Adolphe Quetelet as Statistician by Frank Hamilton Hankins
* The more advanced the sciences have become, the more they have tended to enter the domain of mathematics, which is a sort of center towards which they converge. We can judge of the perfection to which a science has come by the facility, more or less great, with which it may be approached by calculation.
** Edward Mailly, Essai sur la vie et les ouv rages de Quetelet in the Annuaire de Vacadimie royale des sciences des lettres et des beaux-arts de Belgique (1875) Vol. xli pp. 109-297 found also in "Conclusions" of Instructions populaires sur le calcul des probabilités p. 230
* We then better understand the weakness of man, and the power of the Supreme: we are struck with the inflexible constancy of the laws which regulate the march of worlds, and which preside over the succession of human generations.
** Adolphe Quételet. 1981. Letters addressed to H.R.H. the Grand Duke of Saxe Coburg and Gotha, on the theory of probability. Arno Press, p. 132
* The Supreme has then not only spread life and movement throughout, and willed that its impress should be preserved, but has done more; for he has permitted man to associate in some degree with his work, and to modify it.
** Adolphe Quételet. 1981. Letters addressed to H.R.H. the Grand Duke of Saxe Coburg and Gotha, on the theory of probability. Arno Press, p. 134

### A Treatise on Man and the Development of His Faculties (1842)

    A source. Also see People's Edition, Tr. R. Knox & Thomas Smibert, 1st published as Sur L'Homme, et le Développement de ses Facultés (1835)
* The principal artists of the era of the revival of letters, such as Leon Baptista Alberti, Michael Angelo, Leonardo da Vinci, Albert Durer, with many others who what art ought to borrow from science, felt the necessity of resorting to observation, in order to rebuild in some sort the ruined monument of ancient artistical skill. They studied nature in a philosophical manner; sought to strike out the limits within which they ought to confine themselves in order to be truthlike... and from those profound studies which kept them ever before the face of nature, they deduced original views and new models, destined to distinguish for ever that celebrated age. The proportions of the human body did not alone attract their attention: anatomy, perspective, and chemistry, formed parts of their studies; nothing was neglected; and some of these great artists even gained for themselves a first place among the geometers of their day. Their successors have not devoted themselves to such serious studies, and hence it so frequently happens that they are reduced to content themselves, either with copying from those who went before them, or with working after individual models, whose proportions they modify according to mere caprice, without having any just or proper ideas of the beautiful.
** Preface of M. Quetelet
* It would be an error... to suppose that science makes the artist; yet it lends to him the most powerful assistance. In general, it is difficult to keep it within due limits; and I shall even freely admit that Albert Durer, in his work upon the proportions of the human frame, has imparted to it a certain scientific dryness, which lessens its utility. One finds there more of the geometer than the artist, and the geometer, moreover, such as he was at a time when it had not yet been discovered how much the rules of style enhance the value of scientific works, and, above all, of those which appertain at the same time to the domain of the fine arts.
** Preface of M. Quetelet
* Artists have, for the most part, bound themselves down to follow a blind routine. Noble exceptions, however, have presented themselves. Nicholas Poussin, one of the most profound thinkers, whom the arts have produced, took care to correct and regulate by the antique the proportions which Leon Baptista Alberti and Albert Durer had given from the living model.
** Preface of M. Quetelet
* My aim has been, not only to go once more through the task of Albert Durer, but to execute it also on an extended scale.
** Preface of M. Quetelet
* I have sought to determine... the different relations of bulk, subsisting between the various parts of his frame; and to ascertain how far these relations become modified during his development, what they are in the flower of his age, and in what position they remain up to the instant of decay.
** Preface of M. Quetelet
* It is only by long and laborious study, and by the comparison of a number of individuals, that it will be possible to succeed in establishing correct average proportions each age, and in settling the limits betwixt they can be made to vary, without ceasing to be accurate and faithful to nature—our first and guide in this difficult study.
** Preface of M. Quetelet
* I have been surprised to find how little variety of opinion exists, in different places, regarding what they concurred in terming the beautiful.
** Preface of M. Quetelet
* I am less desirous to explain phenomena than to establish their existence.
** Preface of M. Quetelet
* I have always comprehended with difficulty... how persons pre-occupied doubtless by ideas, have seen any tendency to materialism in exposition of a series of facts deduced from documents. In giving to my work the title of Physics, I have had no other aim than to collect, in uniform order, the phenomena affecting man, nearly as physical science brings together the phenomena appertaining to the material world. If certain facts present themselves with an alarming regularity, to whom is blame to be ascribed? Ought charges of materialism to be brought against him who points out that regularity?
** Preface of M. Quetelet
* Judgments upon books are formed with even more haste and levity than judgments upon men. Writings are talked of without being known; and people take up an opinion for or against, in consequence of decisions which it would cost them some trouble to determine the source. These are evils which must be borne with patience, and the more so because they are common.
** Preface of M. Quetelet
* "There are few works on political economy," said Malthus to me, "which have been more spoken and less read than mine." All the absurdities which have been spoken and written respecting the illustrious English author, are well known. Certainly, by an appeal against such decisions, he would have all to gain, and nothing to lose, before a less prejudiced tribunal.
** Preface of M. Quetelet
* From the examination of numbers, I believed myself justified in inferring, as a natural consequence, that, in given circumstances, and the influence of the same causes, we may reckon upon witnessing the repetition of the same effects, reproduction of the same crimes, and the same convictions. What has resulted from this exposition? Timorous persons have raised the cry of fatalism. If, however, some one said, "Man is born free; nothing force his free-will; he underlies the influence of external causes; cease to assimilate him to a machine, or to pretend to modify his actions. Therefore, ye legislators, repeal your laws; overturn your prisons; break your chains in pieces; your convictions penalties are of no avail; they are so many acts barbarous revenge. Ye philosophers and priests, speak no more of ameliorations, social or religious; you are materialists, because you assume to society like a piece of gross clay; you are fatalists, because you believe yourselves predestined to influence man in the exercise of his free-will, and to the course of his actions." If, I say, any one held such language to us, we should be disgusted with its excessive folly. And wherefore? Because we are thoroughly convinced that laws, education, and religion exercise a salutary influence on society, and that moral causes have their certain effects.
** Preface of M. Quetelet
* We both call in experience to the support of our opinions; but, in your case, the experience is based on vague uncertainties, whilst I, more circumspect, strive never to lose sight of those scientific principles which ought to guide the observer in all his investigations. My aim is not to defend systems, or bolster up theories; I confine myself to the citation of facts, such as society presents to our view. If these facts be legitimately established, it follows that we must accept of and accommodate our reason to them.
** Preface of M. Quetelet
* As laws and the principles of religion and morality are influencing causes, I have then not only the hope, but, what you have not, the positive conviction, that society may be ameliorated and reformed.
** Preface of M. Quetelet
* Expect not... that efforts for the moral regeneration of man can be immediately crowned with success; operations upon masses are ever slow in progress, and their effects distant.
** Preface of M. Quetelet
* What becomes of human free will and agency? ...it seems to me to involve one of the most admirable laws of conservation in nature—a law which presents a new proof of the wisdom of the Creator... It is necessary, then, to admit that free-will exercises itself within indefinite limits, if one wishes not to incur the reproach of denying it altogether. But, with all the follies which have passed through the head of man, with all the perverse inclinations which have desolated society, what would have become of our race during so many past ages? All these scourges have passed by, and neither man nor his faculties have undergone sensible alterations, as far at least as our observations can determine. This is because the same finger which has fixed limits to the sea, has set similar bounds to the passions of men—because the same voice has said to both, "Hitherto shalt thou come, and no farther!"
** Preface of M. Quetelet
* What! when it is necessary to take the most simple resolve, we are under the domination of our habitudes, our wants, our social relations, and a host of causes which, all of them, draw us about in a hundred different ways. These influences are so powerful, that we have no difficulty in telling, even when referring to persons whom we are scarcely acquainted with, or even know not at all, what is the resolution to which they will lead such parties. Whence, then, this certainty of foresight, exemplified by you daily, if you were not convinced, at the outset, that it is extremely probable the empire of causes will carry it over free-will. In considering the moral world a priori, you give to this free-will the most entire latitude; and when you come to practice, when you speak of what passes around you, you constantly fall into contradiction with yourselves.
** Preface of M. Quetelet
* But is the anatomy of man not a more painful science still?—that science which leads us to dip our hands into the blood of our fellow-beings to pry with impassible curiosity into parts and organs which once palpitated with life? And yet who dreams this day of raising his voice against the study? Who does not applaud, on the contrary, the numerous advantages which it has conferred on humanity? The time is come for studying the moral anatomy of man also, and for uncovering its most afflicting aspects, with the view of providing remedies.
** Preface of M. Quetelet
* The analysis of the moral man through his actions, and of the intellectual man through his productions, seems to me calculated to form one of the most interesting parts of the sciences of observation, applied to anthropology.
** Preface of M. Quetelet
* It may be seen, in my work, that the course which I have adopted is that followed by the natural philosopher, in order to grasp the laws that regulate the material world. By the seizure of facts, I seek to rise to an appreciation of the causes whence they spring.
** Preface of M. Quetelet
* The tables of criminality for different ages, given in my published treatise, merit at least as much faith as the tables of mortality, and verify themselves within perhaps even narrower limits; so that crime pursues its path with even more constancy than death. ...it is still betwixt the ages of twenty-one and twenty-five, that, all things being equal, the greatest number of persons are to be found in that position [of a criminal].
** Preface of M. Quetelet
* In every instance, it is not my method that is defective; proper observations alone fail me. But will it be ever impossible to have them perfectly precise? I believe that even at present we have them sufficiently so to enter, at least, on the great problem under consideration. Name them as you will, the actions which society stamps as crimes, and of which it punishes the authors, are reproduced every year, in almost exactly the same numbers; examined more closely, they are found to divide themselves into almost exactly the same categories; and, if their number were sufficiently large, we might carry farther our distinctions and subdivisions, and should always find there the same regularity. It will then remain correct to say, that a given species of actions is more common at one given age than at any other given age.
** Preface of M. Quetelet
* The words cited from my work, when viewed isolatedly, are far from expressing the idea which I wished to attach to them. The works of genius upon which our judgments bear are in general complex; for there is no work, constructed by genius, which does not suppose the exercise of various of its faculties. A skilful analysis could alone make out the part of each of them...
** Preface of M. Quetelet
* I would suggest... the idea of a work which should have for its object the analytic examination of the development of our intellectual faculties for each age. Now, I have aimed to present, in the work here reproduced, only an essay, only a particular example, of such an analysis, "which tends to show that the maximum of energy of the passions occurs about the age of twenty-five." The minimum is not then determined; and even when it shall be, by a sufficient number of observations, one will no more be able to apply it to any given individual in particular, than one could make use of a table of mortality to determine the period of his decease.
** Preface of M. Quetelet
* Social physics never can pretend to discover laws which will verify themselves in every particular, in the case of isolated individuals. The science will have rendered a service sufficiently vast, in giving more precise views upon a host of points, of which vague glimpses only were before possessed.
** Preface of M. Quetelet
* We aim at a target—an end—marked by a point. The arrows go to right and left, high or low, according to the address of the shooters. In the mean time, after a considerable number of trials, the butt, which has not yet been touched, perhaps, a single time, becomes so well pointed out by the marks around it, that they would aid at once in rediscovering it, if it should chance to be lost sight of. Nay, more than this; even aims the most unfortunate may be made to conduce to this end; commencing with those marks which are farthest away, if they be sufficiently numerous, one may learn from them the real position of the point they surround.
** Preface of M. Quetelet
* Limits... seem to me of two kinds, ordinary or natural, and extraordinary or beyond the natural. The first limits comprise within them the qualities which deviate more or less from the mean, without attracting attention by excess on one side or the other. When the deviations become greater, they constitute the extraordinary class, having itself its limits, on the outer verge of which are things preternatural... We must conceive the same distinctions in the moral world.
** Preface of M. Quetelet
* Hitherto, the science of Man has been limited to researches... respecting some of its laws, to results deduced from single or insulated observations, and to theories often based on mere glimpses; and these constitute pretty nearly all the materials it possesses.
** Introductory
* The progressive development of moral and intellectual man has scarcely occupied their [scientists] attention; nor have they noted how the faculties of his mind are at every age influenced by those of the body, nor how his faculties mutually react.
** Introductory
* Having for their object the Science of Man, present difficulties exceedingly great, and, to merit confidence, must be collected upon a scale far too extended to be attempted by an individual philosopher.
** Introductory
* It is of primary importance to keep out of view man as he exists in an insulated, separate, or in an individual state, and to regard him only as a fraction of the species. In thus setting aside his individual nature, we get quit of all which is accidental, and the individual peculiarities, which exercise scarcely any influence over the mass, become effaced of their own accord, allowing the observer to seize the general results.
** Introductory
* A person examining too nearly a small portion of a very large circle... would see in this detached portion merely a certain quantity of physical points, grouped in a more or less irregular manner, and so, indeed, as to seem as if they had been arranged by chance... But, placing himself at a greater distance, the eye embraces of necessity a greater number of points, and already a degree of regularity is observable... and by removing still farther from the object, the observer loses sight of the individual points, no longer observes any accidental or odd arrangements amongst them, but discovers at once the law presiding over their general arrangements, and the precise nature of the circle so traced.
** Introductory
* To him... who had examined the laws of light merely in a drop of water, the brilliant phenomenon of the rainbow would be totally unintelligible.
** Introductory
* Even in respect to those crimes which seem perfectly beyond human foresight, such as murders committed in general at the close of quarrels, arising without a motive, and under other circumstances to all appearance the most fortuitous or accidental; nevertheless, experience proves that murders are committed annually, not only pretty nearly to the same extent, but even that the instruments employed are in the same proportions. Now, if this occurs in the case of crimes whose origin seems to be purely accidental, what shall we say of those admitted to be the result of reflection.
** Introductory
* We might even predict annually how many individuals will stain their hands with the blood of their fellow-men, how many will be forgers, how many will deal in poison, pretty nearly in the same way as we may foretell annual births and deaths.
** Introductory
* Every social state supposes... a certain number and a certain order of crimes, these being merely the necessary consequences of its organisation. This observation, so discouraging at first sight, becomes, on the contrary, consolatory, when examined more nearly, by showing the possibility of ameliorating the human race, by modifying their institutions, their habits, the amount of their information, and, generally, all which influences their mode of existence.
** Introductory
* This observation is merely the extension of a law well known to all who have studied the condition of society in a philosophic manner: it is, that so long as the same causes exist, we must expect a repetition of the same effects. What has induced some to believe that moral phenomena did not obey this law, has been the too great influence ascribed all times to man himself over his actions.
** Introductory
* It is a remarkable fact in the history of science, that the more extended human knowledge has become, the more limited human power, in that respect, has constantly appeared. This globe, of which man imagines the haughty possessor, becomes, in the eyes of astronomer, merely a grain of dust floating in immensity of space: an earthquake, a tempest, an inundation, may destroy in an instant an entire people, or ruin the labours of twenty ages. ...But if each step in the career of science thus gradually diminishes his importance, his pride has a compensation in the greater idea of his intellectual power, by which he has been enabled to perceive those laws which seem to be, by their nature, placed for ever beyond his grasp.
** Introductory
* Moral phenomena, when observed on a great scale, are found to resemble physical phenomena; and we thus arrive... at the fundamental principle, that the greater the number of individuals observed, the more do individual peculiarities, whether physical or moral, become effaced, and leave in a prominent point of view the general facts, by virtue of which society exists and is preserved.
** Introductory
* This reaction of man upon himself, is one of his noblest attributes; it offers, indeed, the finest field for the display of his activity. As a member of the social body, he is subjected every instant to the necessity of these causes, and pays them a regular tribute; but as a man, employing all the energy of his intellectual faculties, he in some measure masters these causes, and modifies their effects, thus constantly endeavouring to improve his condition.
** Introductory

## Quotes about Quetelet

* The influence of Quetelet's ideas spread throughout the sciences, even to the physical sciences. The two primary founders of the modern kinetic theory of gases, based on considerations of probability, were James Clerk Maxwell and Ludwig Boltzmann. Both acknowledged their debt to Quetelet. ...historians generally consider the influence of the natural sciences on the social sciences, whereas in the case of Maxwell and Boltzmann, there is an influence of the social sciences on the natural sciences, as Theodore Porter has shown.
** I. Bernard Cohen, The Triumph of Numbers: How Counting Shaped Modern Life (2005)
* God had been forcefully excluded from astronomy during the French Revolution, when Pierre-Simon Laplace rewrote Newton's ideas to create his [Laplace's] deterministic cosmos, in which scientific laws govern every movement of every planet with no need for divine intervention. Inspired by his success, a Belgian astronomer called Alphonse Quetelet decided that human societies are also controlled by laws. ...and so Quetelet suggested that an 'average man' can consistently encapsulate a nation's characteristics. ...Quetelet's successors took his ideas in many different directions. ...Data collection projects proliferated, and statisticians searched for laws governing every aspect of life. ...In physics, the most important application of statistics was to gases.
** Patricia Fara, Science A Four Thousand Year History (2009)
* The most important of Quetelet's statistical principles... include the conception of the Average Man as a type, the significance for social science of the regularities found in the moral actions of man, and the theoretical basis of the distribution of group phenomena about their type.
** Frank Hamilton Hankins, Adolphe Quetelet as Statistician (1908)
* Quetelet published quite a number of poems, and until the age of thirty he continued to exercise his poetical talents as pastime and relief from his scientific studies. His poems were of a serious tone, but were well received by both public and critics. We may mention here an Essai sur la romance, which Quetelet brought out in 1823. ...This essay, together with translations, in prose and in verse, of German, English, Italian, and Spanish romances, shows Quetelet's wide acquaintance at that early age with the various European literatures.
** Hankins, ibid.
* As a man of science he was admired; in political affairs he was respected; in private life he was beloved.
** Hankins, ibid. quoting a Speaker at Quetelet's funeral
* In the history of natural science, Quetelet will, with good right, be placed in the rank of Pascal, Leibnitz, Bernoulli, Laplace, Poisson, and such scientists.
** Hankins ibid. quoting from Von John, Geschichte der Statistik, erster Teil, von dem Ursprung der Statistik bis auf Quetelet (1835) p. 335
* The mere enumeration of his contributions to pure and mixed mathematics would occupy a very large space, and from their intrinsic merit, patient and conscientious research and earnest regard for truth, would alone have secured him a foremost place among the distinguished and scientific men of the present century.
** Hankins ibid. quoting F. J. Mouat, "Monsieur Quetelet," Journal of the Statistical Society of London (1875) Vol. xxxvii p. 114
* The mere enumeration of his contributions to pure and mixed mathematics would occupy a very large space, and from their intrinsic merit, patient and conscientious research and earnest regard for truth, would alone have secured him a foremost place among the distinguished and scientific men of the present century.
** F. J. Mouat, "Monsieur Quetelet," Journal of the Statistical Society of London (1875), vol. xxxvii, p. 114.
* In principle, wrote Quetelet, the courage or criminality of a real person could be established... but it was wholly unnecessary for social physics. Instead, the physicist need only arrange that courageous and criminal acts be recorded throughout society, as the latter already were, and then the average man could be assigned a "penchant for crime" equal to the number of criminal acts committed divided by the population. In this way, a set of discrete acts by distinct individuals was transformed into a continuous magnitude... an attribute of the average man.
** Theodore M. Porter, The Rise of Statistical Thinking, 1820-1900 (1986)
* Maxwell... mastered electricity and magnetism, light and heat, pretty much mopping up all the major areas of physics beyond those that Newton had... taken care of—gravitation and the laws of motion. ...Maxwell detected an essential shortcoming in Newton's laws of motion, too. They worked... for macroscopic objects, like cannonballs and rocks. But what about the submicroscopic molecules from which such objects were made? ...Newton's laws ...did you no good because you could not possibly trace the motion of an individual molecule ...Maxwell applied the sort of statistical thinking that Quetelet had promoted.
** Tom Siegfried, A Beautiful Math (2006) Ch. 7: Quetelet's Statistics and Maxwell's Molecules, pp. 135-136.
* Maxwell probably first encountered Quetelet in an article by... John Herschel... (...familiar with Quetelet as a fellow astronomer). Later, in 1857, Maxwell read a newly published book by... Henry Thomas Buckle. Buckle, himself clearly influenced by Quetelet, believed that science could discover the "laws of the human mind" and that human actions are a part of "one vast system of universal order." ...Though Maxwell found Buckle's book "bumptious," he recognized it as a source of original ideas, and the statistical reasoning Buckle applied to society seemed just the thing... needed to deal with molecular motion.
** Tom Siegfried, A Beautiful Math (2006) Ch. 7: Quetelet's Statistics and Maxwell's Molecules, pp. 136-138.
* No other work in the English language contains such an extensive and succinct account of the different branches of physics or exhibits such a general knowledge of the whole field in so small a compass.
** Robert Wallace, Preface, Facts, Laws and Phenomena of Natural Philosophy, or a Summary of a Course in General Physics (1835) Wallace's English translation of Quetelet's Positions de physique ou résumé d' un cours de physique générale (1826)

## External links

* Adolphe J. Quetelet, A Treatise on Man and the Development of his Faculties Tr. R. Knox (1835)
* Frank Hamilton Hankins, Adolphe Quetelet as Statistician (1908)