In the year 1778, when the Academy of Sciences at Berlin proposed a prize for the best dissertation on the theory of comets, Condorcet transmitted an essay, whiCh was however unsuccessful. It was published along with one of Tempelhoff's and two of Hennert's prize disser tations, in a quarto volume, entitled Dissertations sur la Theorie des Cometes. Utrecht, 1780.
Upon the death of D'Alembert in 1783, Condorcet succeeded, in virtue of his former appointment, to the Secretaryship of the Academy of Sciences, and in this office he distinguished himself by his Eloges on some of the most celebrated members. His Account of the Life and discoveries of D'Alembert and Euler ; his Eloge on the celebrated Turgot; his life of Voltaire, which appeared in 1787 ; and his Biographical Account of Dr Franklin, which appeared in 1790, display a deep knowledge of science and of character, and exhibit the peculiar talent which Condorcet eminently possessed, of giving a perspicuous and comprehensive view of the labours and discoveries of others.
Amidst the duties of his new office, Condorcct did not forget his mathematical pursuits. His attention was turned particularly to the doctrine of chances ; and he treated this subject in a series of four memoirs, enti tled, Sur le Calcul des Probabilites, and printed in the Memoirs of the Academy between 1781 and 1785. He pub lished also a separate work on the subject entitled, Essai sur application d'analyse a laProbabilite des Dicisions, 4to, 1785. In the application of the results of his investiga tions to the practical purposes of life, he examined the probability of an assembly's giving a true decision, and he explained the limits to which our knowledge of fu ture events might extend, when regulated by the laws of nature. He supposed that we have, at least, a mean pro bability that the law indicated by events is constant, and will be perpetually observed. He regarded a forty-five thousandth part as the value of the risk, in the case when the consideration of a new law comes under our notice ; and it results from his formulae, that an assembly con sisting of 61 voters, where it is requisite that there should be a plurality of nine, will fulfil this condition, if there is a probability that each vote is equal to five-fifths, that is, if there is a probability that each member shall be deceived only once in five times. These calculations he next applies to the establishment of tribunals, to the forms of elections, and to the decision of numerous as semblies.
Condorcet was at this time employed, in conjunction with M. Sejour and M. de la Place, in estimating the population of France ; and the results of their labours were successively laid before the public in six memoirs, which were published in the memoirs of the Academy between the years 1784 and 1788.
About this time Condorcet had suggested the idea of a dictionary, in which objects are to be found by their properties, instead of by their respective names ; and he at the same time gave notice of a scheme for con structing Tables, by means of which ten milliards of objects might be classed together by only ten different modifications.
Condorcet took an active part in the various political events which preceded and accompanied the French re volution, and his numerous writings on philosophical and political subjects are supposed to have accelerated that awful event. Ile conducted a work entitled La Bibliotheque de l'Ilomme Public, containing analyses of the works of the most eminent political writers ; and a newspaper called La Chronique de Paris, which was filled with the most petulant declamation against royalty.
When the king of France fled to Varennes, Condor cet united himself with Brissot and Thomas Paine, two of the most determined republicans, and none of whom were members of the constituent assembly ; and they commenced a periodical paper, called Renublieain, ou It Dtlenseur du Gouvernment Reprcsentatif, which was filled with the most detestable principles. The papers written by Thomas Paine were translated by the Mar chionese de Condorcet ; but Condorcet was the principal contributor to this disgraceful publication. In one of the papers which he published in the RePublitain, Con dorcet attempts to refute the argument in favour of a monarchical government, that a legal king is the best security against a tyrant, since a power limited by the constitution is less formidable than the undefined power of an ambitious usurper ; and after adducing a variety of arguments to prove, that there is now less danger of usur pation than there was in the days of Sylla, Caesar, Guise, and Cromwell, he maintains, that, in future, the art of printing, the liberty of the press, and the free communi cation of knowledge by means of newspapers, will infal libly preserve the human race from similar usurpations.* Condorcet lived long enough to see this contemptible reasoning completely refuted by the usurpation of Robe spierre ; and those who survived him have witnessed another refutation of it still more triumphant. It is thus that the great events of life are constantly putting to shame the speculations of that school of philosophy, which, ignorant of the true character and destiny of man, represents him as hastening to a state of perfection of which his nature is unsusceptiblc.