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better secured from inconsistencies, that is, from asserting or denying any thing in one place, which contradicts what you have asserted or denied in another : and to attain these ends, an extensiveness of understanding, and a large memory, are of unspeakable service.
One would be ready to wonder sometiines how easily grcat and wise and learned men are led into assertions in some parts of the same treatise, wbich are found to be scarce consistent with what they have asserted in other places; but the true reason is, the narrowness of the mind of man, that it cannot take in all the innumerable properties and relations of one subject with a single view ; and therefore whilst they are intent on one particular part of their theme, they bend all their force of thought to prove or disprove some proposition that relates to that part, without a sufficient attention to the consequences which may flow from it, and which may unhappily affect another part of the same subject : and by this means they are sometimes led to say things which are inconsistent. In such a case, the great dealers in dispute and controversy take pleasure to cast nonsense and selfcontradiclion on their antagonist with huge and hateful reproaches. For my part, I rather choose to pity human nature, whose necessary narrowness of understanding exposes us all to some degrees of this frailty. But the most extensive survey possible of our whole subject is the best remedy against it. It is our judging and arguing upon a partial view of things, that exposes us to mistakes, and pushes us into absurdities, or at least to the very borders of thein.
III.“ In searching the knowledge of things, always keep the precise point of the present question in your eye." Take heed that you add nothing to it while you are arguing, nor omit any part of it. Watch carefully, lest any new ideas slidein to mingle themselves either with the subject or the predi-cate., Şee that the question be not altered by the ambiguity of any word taken in different senses; nor lest any secret prejudices of your own, or the sophistical arts of others, cheat your understanding by changing the question, or shuffling in any thing else in its room.
And for this end it is useful to keep the precise matter of enquiry as simple as may be, and disengaged from a complication of ideas, which do not necessarily belong to it. By admitting a co:nplication of ideas, and taking too many things at once into one question, the mind is sometimes dazzled and bewildered, and the truth is lost in such a variety and confusion of ideas; whereas by limiting and narrowing the question, you take a fuller survey of the whole of it.
By keeping the single point of enquiry in our constant view, we shall be secured froin sudden, rash, and impertinent
responses and determinations, which some have obtruded in. stead of solutions and solid answers, before they perfectly knew the question.
JV.“ When you have exactly considered the precise point of enquiry, or what is unknown in the question, then consider what, and how much you know already of this question, or of the ideas and terms of wbich it is composed.” It is by a comparison of the known and unknown parts of the question together, that you find what reference the part known hath unto, or what connections it hath with the thing that is sought : those ideas, whereby the known and ur.known parts of the question are connected, will furnish you with middle terms or arguments whereby the things proposed may be proved or disproved.
In this part of your work, namely, comparing ideas together, take due time, and be not too hasty to come to a determination, especially in points of importance. Some men when they see a little agreement or disagreement between ideas, they presume a great deal, and so jump into a conclusion. This is a short way to fancy, opinion and conceit, but a most unsafe and uncertain way to true knowledge and wisdom.
V. “In choosing your middle terms or arguinent to prove any question, always take such topics as are surest and least fallible, and which carry the greatest evidence and strength with them.” Be not so solicitous about the number, as the weight of your arguments, especially in proving any proposition which admits of natural certainty, or of complete demonstration. Many times we do injury to a cause by dwelling upon trifling arguinents. We amuse our hearers with uncertainties, by multiplying the number of feeble reasonings, before we mention those which are more substantial, conclusive, and convincing. And too often we yield up our own assent to mere probable arguments, where certain proofs may be obtained. Yet it must be confessed there are many cases wherein the growing number of probable arguments increases the degree of probability, and gives a great and sufficient confirmation to the truth which is svught; as,
(1.) When we are enquiring the true sense of any word or phrase, we are more confirmed in the signification of it, by find. ing the same expression so used in several authors, or in several places of the same author.
(2.) When we are searching out the true meaning or opinion of any writer, or enquiring into any sacred doctrine of scripture, we come to a surer determination of the truth by several distinct places wherein the same thing is expressed or plainly implied ; because it is not so probable that an honest skilful reader should mistake the meaning of the writer'in many places, as be may in one or two.
(3.) When we would prove the importance of any scriptural doctrine or duty, the multitude of texts, wherein it is rea' peated and inculcated upon the reader, seems naturally to instruct us that it is a matter of greater iinportance, than other things which are but slightly or singly mentioned in the Bible.
(4.) In searching out matters of fact in times past, or in distant places, in which case moral evidence is sufficient, and moral certainty is the utmost which can be attained, here we derive a greater assurance of the truth of it by a number of persons, or a multitude of circumstances concurring to bear witness to it.
(5.) From many experiinents in natural philosophy, we more safely infer a general theorem, than we can from one or two.
(6.) In matters which require present practice, both sacred and civil, we must content ourselves oftentimes with a mere pre-, ponderation of probable reasons or arguments. Where there are several reasons on each side, for and against a thing that is to be done or omitted, a small argument added to the heap may. justly turn the balance on one side, and determine the judgment, as I have noted in the Secoud Part of Logic.
To conclude ; a growing acquaintance with matters of learning, and a daily improvement of our understandings in affairs human and divine, will best teach us to judge and distin.. guish in what cases the number of arguments adds to their weight and force. It is only experience can fully inform us when we must be determined by probable topics, and when we must seek and expect demonstrations.
VI. “ Prove your conclusion (as far as possible) by some propositions that are in themselves more plain, evident, and certain, than the conclusion ; or at least such as are more known, and more intelligible to the person whom you would convince.", If we neglect this rule, we shall endeavour to eplighten that which is obscure by something equally or more obscure, and to confirm that which is doubtful by something equally or more un. certain. Common sense dictates to all men, that it is impossible to establish any truth, and to convince others of it, but by something that is better known to them than that truth is.
VII. “ Labour in all your arguings to enlighten the understanding, as well as to conquer and captivate the judgment." Argue in such a manner as may give a natural, distinct, and solid knowledge of things to your bearers, as well as to furce their . assent by a mere proof of the question. Now to attain this end, the chief topic or medium of your demonstration should be fetched as much as possible, from the nature of the thing to be proved, or from those things which are most naturally connected with it. Geometricians sometimes break this rule without necessity, two ways; namely,
1. When they prove one proposition only by shewing what absurdities will follow if the contradictory proposition be supposed or admitted. This is called reductio ad absurdum*, or demon. stratio impossible. As for instance, when they prove all the radic of a circle to be equal, by supposing one radius to be longer or shorter than another, and then shewing what absurd consequences will follow. This, I coníess, forces the assent, but it does not enlighten the mind, by shewing the true reason and cause why all radii are equal, which is derived from the very construction of a circle: for since a circle is formed by fixing one end of a straight line in the centre, and moving the other end round, (or, which is all one, by coinpasses kept open to a certain extent) it follows evidently that every part of the circumference being thus described, must be equally distant from the centre, and therefore the radii, which are lines from the centre to the circumference must be all equal.
2. Geometricians forget this rule, when they heap up many far-fetched lines, figures and propositions, to prove some plaia, simple, and obvious propositions. This is called a demonstration per aliena & remota, or an argument from unnatural and remote mediums; as if, in order to prove the radii of a circle are all equal, I should make several triangles and squares about the circle, and then from some properties and propositions of squares and triangles prove that the radii of a circle are equal.
Yet it must be confessed, that sometimes such questions bappen, that it is hardly possible to prove them by direct arguments drawn from the nature of things, &c. and then it may not only be lawful but necessary to use indirect proofs, and arguments drawn from remote mediums, or from the absurdity of the contradictory suppositions.
Such indirect and remote arguments may also be sometimes used to confirm a proposition, which has been before proved by arguments more direct and immediate.
VIII. Though arguments should give light to the sabject, as well as constrain the assent, yet you must learn to a distinguish well between an explication and an argument, and neither impose upon yourselves, nor suffer yourselves to be imposed upon by others, by mistaking a mere illustration for a convincing
Axioms themselves, or self-evident propositions, may want an explication or illustration, thougir they are not to be proved by reasoning
* Note, This rule chiefly refers to the establishment of some truth, rather thao to be refutation of error. It is a very common and useful way of arguing, to refute a false proposition, by sbewing what evident falsebood or absurdity will follow from it; for what proposition soever is really absurd and false, does eflectually prove that principle to be false from which it is derived, so that this way of refutiog an error is not so usually called reductio ad absurdum.
Similitudes and allusions have oftentimes a very happy influence to explain some difficult truth, and to render the idea of it familiar and easy. Where the resemblance is just and accurate, the influence of a simile may proceed so far as to shew the possibility of the thing in question : but similitudes must not be taken as a solid proof of the truth or existence of those things to which they have a resemblance. A too great deference paid to similitudes, or an utter rejection of them, seem to be two extremes, and ought to be avoided. The late ingenious Mr. Locke, even in his Enquiries after truth, makes great use of similies for frequent illustration, and is very happy in the invention of them, though he waros us also lest we mistake them for conclusive ara guments.
Yet let it be noted here, that a parable or a similitude used by any author, may give a sufficient proof of the true sense and meaning of that author, provided that we draw not this similitude beyond the scope and design for which it was brought ; as when our Saviour affirms ; Rev. iii. 3. I will come on thee as a thief ! this will plainly prove that he describes the unexpectedness of his appearance, though it is by no means to be drawn to signify any injustice in his design.
IX. “ In your whole course of reasoning keep your mind sincerely intent on the pursuit of truth; and follow solid argument wheresoever it leads you." Let pot a party spirit, nor any passion or prejydice whatsoever, stop or avert the current of reasoning in quest of true knowledge.
When you are enquiriog therefore into any subject, maintain a due regard to the arguments and objections on both sides of a question, Consider, compare, and balance them well, before you determine for one side. It is a frequent, but a very faulty practice, to hunt after arguments only to make good one side of a question, and entirely to neglect and refuse those which favour the other side. If we have not given a due weight to arguments on both sides, we do but wilfully misguide our judgment, and abuse our reason, by forbidding its search after truth. When we espouse opinions by a secret bias on the mind, through the influence of fear, hope, honour, credit, interest, or any other prejudice, and then seek arguments only to support those opinions, we have neither done our duty to God nor to ourselves ; and it is a matter of mere chance if we stumble upon truth in our way to ease and preferment. The power of reisoning was given us by our Maker for this very end, to pursue truth ; and we abuse one of bis richest gifts, if we basely yield it up to be led astray by any of the meaner powers of nature, or the perishing interests of this life. Reason itself, if honestly obeyed, will lead us to receive the divine revelation of the gospel, where it is duly proposed, and this will shew us the path of life everlasting.