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ART. I. - 1. Lettres à S. A. R. le Duc règnant de Saxe
Cobourg et Gotha sur la Théorie des Probabilités appliquée aux Sciences Morales et Politiques. Par M. A. QUETELET, Astron. Royal de la Belgique, &c. &c. 1 vol. in 8vo. 1846.
Chez M. Hayez, à Bruxelles. 2. Letters addressed to H. R. H. the Grand Duke of Sare-Co
bourg and Gotha on the Theory of Probabilities as applied to the Moral and Political Sciences. By M. A. QUETELET, Astronomer Royal of Belgium, Corresponding Member of the Institute of France, &c. &c. Translated from the French by OLINTHUS GREGORY DOWNEs, of the Economic Life
Assurance Society. London: 1849. EXPERIENCE has been declared, with equal truth and poetry, e to adopt occasionally the tone, and attain to something like the certainty, of Prophecy. In the contemplating mind the past and the future are linked by a bond as indissoluble as that which connects them in their actual sequence. Metaphysicians may dispute concerning the nature of causation ; and it will always, no doubt, be difficult to explain and demonstrate the objective reality of that relation: but the reality, as an internal feeling, of the expectation that what has happened under given circumstances will happen again under precisely similar circumstances, is independent of metaphysical dispute and above it. It is an axiom drawn from the inward consciousness of our nature by involuntary generalisation. We acknowledge it expressly or impliedly in every instant of life. It is the practical ground of
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every sane transaction. Instinctive in childhood — or if not instinctive, the direct result of the earliest, simplest, and most powerful associations — it becomes, however, entangled with conditions and modifications, as reason enlarges her sphere of vision, and we learn to question the absolute similarity of circumstances in any two assigned cases. But though puzzled for a while, and baffled as by a verbal quibble, the impression itself is not destroyed or weakened. We begin early to distinguish between relevant and irrelevant circumstances; to attend only to the former and to disregard the latter. Upon this ground Inductive Science takes her stand and erects her axioms; making it her business to ascertain, in each case, what are the really relevant circumstances on which events depend, and to analyse the complicated web of phenomena into a system of elementary and superposed uniformities, to which we assign the name of inductive theorems, or laws of nature.
One of the greatest steps which have yet been made in the philosophy of Logic — a step which may almost be termed a discovery when we consider the inveteracy of the habits and prejudices which it has cast to the winds—is that recently taken by Vr. Mill*, in showing that all reasoning (meaning thereby the investigation of truth as distinguished from the mere interpretation of a formula) is from particulars to particulars, and in tbence assigning to general propositions their true character and to the syllogism its true office. But while a vast accumulation of rubbish, which obscured the basis of all sound philosophy, has thus been swept away, a condition of affairs is disclosed which, at first sight, seems to annul our prospect of attaining to any general knowledge whatever, — at least in those of its departments in which analogies are not at once perceived to be identities. No one has ever yet contended that our knowledge of special facts is intuitive. The questions, therefore, at once arise, Ist. What sort of security have we for the truth of any assertion concerning any external thing or fact which has not been made a matter of direct observation ? and, 2dly. What measure have we of the degree or amount of that security, supposing we possess it in some degree, and supposing absolute and mathematical certainty to be unattainable ?
Now, with regard to the first of these questions, it must at
** System of Logic, 21 ed. chap. 3. on the functions and logical value of the Syllogism. Perhaps Mr. Mill may be considered as only following out more emphatically the views originally taken by Berkeley on this subject, but which seem to have dropped so far out of notice as to give their revival all the force of novelty.