CHAPTER IL 417 IV. Reasoning is the next sort of evidence, and that is, when one truth is inferred or drawn from others by natural and just methods of argument ; as, if there be much light at mid- night, I infer, it proceeds from the moon ; because the sun is under the earth°. If I see a cottage in a forest, I conclude, some man lias been there and built it. Or when I survey the heavens and earth, this gives* evidence to my reason, that there is a God who made them. The propositions which I believe upon this kind ofevidence, are called conclusions or rational truths ; and the knowledge that we gain this way is properly called science. Yet let it be noted, that the word science is usually applied to a whole body of regular or methodical observations or pro- positions, which learned men have formed concerning any sub- ject of speculation, deriving one truth from another by a train of arguments. If this knowledge chiefly directs our practice, it is usually called an art. And this is the most remarkable distinction between an art and a science, namely, the one refers chiefly to practice, the other to speculation. Natural philo- sophy, or physics, and ontology, are sciences ; Logic and rhetoric are called arts ; but mathematics include both art and science ; for they have much of speculation, and much of prac- tice in them. Observe here, That when the evidence of a proposition derived from sense, consciousness, intelligence, or reason, is firm and indubitable, it produces such assent as we call a natural certainty. V. When we derive the evidence of any proposition from the testimony of others, it is called the evidence of faith; and this is a large part of our knowledge. Ten thousand things there are which we believe merely upon the authority or credit of those who have spoken or written of them. It is by this evi- dence that we know there is such a country as China, and there was such a man as Cicero who dwelt in Rome. It is by this that most of the transactions in human life are managed : we know our parents and our kindred by this means, we know the persons and laws of our present governors, as well as things that are at a vast distance from us in foreign nations, or in an- cient ages. According as the persons that inform us of any thing are many or few, or more or less wise, and faithful, and credible, so our faith is more or less firm or wavering, and the proposition believed is either certain or doubtful ; but in matters of faith, an exceeding great probability is called a moral certainty. * Note, Since this book was written, we have had to many appearances of the aurora borealis as reducer this inference only to a probability. VOL, vii. D D
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