Billeder på siden

standing, capable of reflecting upon its own operations. Therefore, to make logic the first branch of science that is to be taught, is an old error that ought to be corrected.

SECT. 2. Of the Improvement of Logic.

In compositions of human thought expressed by speech or by writing, whatever is excellent and whatever is faulty, fall within the province either of grammar, or of rhetoric, or of logic. Propriety of expression is the province of grammar; grace, elegance, and force, in thought and in expression, are the province of rhetoric; justice and accuracy of thought are the province of logic.

The faults in composition, therefore, which fall under the censure of logic, are obscure and indistinct conceptions, false judgment, inconclusive reasoning, and all improprieties in distinctions, definitions, division, or method. To aid our rational powers, in avoiding these faults and in attaining the opposite excellencies, is the end of logic; and whatever there is in it that has no tendency to promote this end, ought to be thrown out.

The rules of logic being of a very abstract nature, ought to be illustrated by a variety of real and striking examples taken from the writings of good authors. It is both instructive and entertaining, to observe the virtues of accurate composition in writers of fame. We cannot see them, without being drawn to the imitation of them, in a more powerful

powerful manner than we can be by dry rules. Nor are the faults of such writers, less instructive or less powerful monitors. A wreck, left upon a shoal or upon a rock, is not more useful to the sailor, than the faults of good writers, when set up to view, are to those who come after them. It was a happy thought in a late ingenious writer of English grammar, to collect under the several rules examples of bad English found in the most approved authors. It were to be wished that the rules of logic were illustrated in the same manner. By these means, a system of logic would become a repository; wherein whatever is most acute in judging and in reasoning, whatever is most accurate in dividing, distinguishing and defining, should be laid up and disposed in order for our imitation; and wherein the false steps of eminent authors should be recorded for our admonition.

After men had laboured in the search of truth near two thousand years by the help of syllogisms, Lord Bacon proposed the method of induction, as a more effectual engine for that purpose. His Nocum Organum gave a new turn to the thoughts and labours of the inquisitive, more remarkable and more useful than that which the Organum of Aristotle had given before; and may be considered as a second grand æra in the progress of human


The art of syllogism produced numberless disputes; and numberless sects who fought against


each other with much animosity, without gaining or losing ground, but did nothing considerable for the benefit of human life. The art of induction, first delineated by Lord Bacon, produced numberless laboratories and observatories; in which Nature has been put to the question by thousands of experiments, and forced to confess many of her secrets, that before were hid from mortals. And by these, arts have been improved, and human knowledge wonderfully increased.

In reasoning by syllogism, from general principles we descend to a conclusion virtually contained in them. The process of induction is more arduous; being an ascent from particular premises to a general conclusion. The evidence of such general conclusions is probable only, not demonstrative but when the induction is sufficiently copious, and carried on according to the rules of art, it forces conviction no less than demonstration itself does,

The greatest part of human knowledge rests upon evidence of this kind. Indeed we can have no other for general truths which are contingent in their nature, and depend upon the will and ordination of the Maker of the world. He governs the world he has made, by general laws. The effects of these laws in particular phenomena, are open to our observation; and by observing a train of uniform effects with due caution, we may at last


decypher the law of nature by which they are regulated.

Lord Bacon has displayed no less force of genius in reducing to rules this method of reasoning, than Aristotle did in the method of syllogism. His NoDum Organum ought therefore to be held as a most important addition to the ancient logic. Those who understand it, and enter into its spirit will be able to distinguish the chaff from the wheat in philosophical disquisitions into the works of God. They will learn to hold in due contempt all hypotheses and theories, the creatures of human imagination; and to respect nothing but facts sufficiently vouched, or conclusions drawn from them by a fair and chaste interpretation of nature.

Most arts have been reduced to rules, after they had been brought to a considerable degree of perfection by the natural sagacity of artists; and the rules have been drawn from the best examples of the art, that had been before exhibited: but the art of philosophical induction was delineated by Lord Bacon in a very ample manner, before the world had seen any tolerable example of it. This, although it adds greatly to the merit of the author, must have produced some obscurity in the work, and a defect of proper examples for illustration. This defect may now be easily supplied, from those authors who, in their philosophical disquisitions, have the most strictly pursued the path pointed out in the Novum Organum. Among these Sir Isaac Newton



Newton appears to hold the first rank; having, in the third book of his Principia and in his Optics, had the rules of the Novum Organum constantly in his eye.

I think Lord Bacon was also the first who endeavoured to reduce to a system the prejudices or biasses of the mind, which are the causes of false judgments, and which he calls the idols of the human understanding. Some late writers of logic have very properly introduced this into their system; but it deserves to be more copiously handled, and to be illustrated by real examples.

It is of great consequence to accurate reasoning. to distinguish first principles which are to be taken for granted, from propositions which require proof. All the real knowledge of mankind may be divided into two parts: the first consisting of self-evident propositions; the second, of those which are deduced by just reasoning from self-evident propositions. The line that divides these two parts ought to be marked as distinctly as possible; and the principles that are self-evident reduced, as far as can be done, to general axioms. This has been done in mathematics from the beginning, and has tended greatly to the advancement of that science. It has lately been done in natural philosophy: and by this means that science has advanced more in an hundred and fifty years, than it had done before in two thousand. Every science is in an unformed state until its first principles are ascertain


« ForrigeFortsæt »