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The pursuit of truth is no less pleasant than the pursuit of any
other good *. Our knowledge of what is agreeable and disagreeable in objects is derived from the sense of beauty, handled in Elements of Criticism. Our knowledge of right and wrong in actions, is derived froin the moral sense, to be handled in the sketch immediately following. Our knowledge of truth and error is derived from various fources.
Qur external senses are one source of knowledge : they lay open to us external subjects, their qualities, their actions, with events produced by these actions. . The internal senses are another source of knowledge : they lay open to us things passing in the mind; thinking, for example, deliberating, inclining, resolving, willing, consenting, and other acts; and they also lay open to us our emotions and passions. There is a sense by which we perceive the truth of many propositions ; such as, That every thing which begins
* It has been wisely observed, that truth is the same to the understanding that mufic is to the ear, or beauty to the eye.
to exist must have a cause; That every effect adapted to some end or purpose, proceeds from a designing cause; and, That every effect adapted to a good end or purpose, proceeds from a designing and benevolent caufe. A multitude of axioms in every science, particularly in mathematics, are equally perceived to be true. By a peculiar fense, of which afterward, we know that there is a Deity. There is a sense by which we know, that the external figns of passion are the same in all men; that animals of the same external appearance, are of the same species ; and that animals of the fame species, have the same properties (a). There is a sense that dives into futurity : we know that the sun will rise to-morrow; that the earth will perform its wonted course round the fun; that winter and summer will follow each other in succession; that a stone dropt from the hand will fall to the ground; and a thousand other such propositions.
There are many propositions, the truth of which is not fo apparent': a process of
(a) Preliminary Discourse.
reasoning reasoning is necessary, of which afterward.
Human testimony is another source of knowledge. So framed we are by nature, as to rely on human testimony; by which we are informed of beings, attributes, and events, that never came under any of our senses.
The knowledge that is derived from the sources mentioned, is of different kinds. In some cases, our knowledge includes absolute certainty, and produces the highest degree of conviction : in other cafes, probability comes in place of certainty, and the conviction is inferior in degree Knowledge of the latter kind is distinguished into belief, which concerns facts and opinion, which concerns relations, and other things that fall not under the denomination of facts. In contradistinction to opinion and belief, that fort of knowledge which includes absolute cer-: tainty and produces the highest degree of conviction, retains its proper name. To. explain what is here said, I enter into particulars.
The sense of seeing, with very ceptions, affords knowledge properly so
termed : it is not in our power to doubt of the existence of a person we see, touch, and converse with. When fuch is our constitution, it is a vain attempt to call in question the authority of our sense of feeing, as some writers pretend to do. No one ever called in question the existence of internal actions and passions, laid open to us by internal fenfe ; and there is as little ground for doubting of what we see. The fense of seeing, it is true, is not always correct: through different mediums the fame object is seen differently: to a jaundic'd
eye every thing appears yellow; and to one intoxicated with liquor, two candles fometimes appear four. But we are never left without a remedy in such a case : it is the province of the reasoning faculty, to correct every error of that kind.
An object of sight recalled to mind by the power
is termed an idea or secondary perception. An original perception, as faid above, affords knowledge in its proper sense; but a secondary perception affords belief only. And Nature in this, as in all other instances, is faithful to truth; for it is evident, that we
'cannot * I have given this proposition a place, because it is assumed as an axiom by all writers on natural philosophy. And yet there appears some room for doubting, whether our conviction of it do not proceed from a bias in our nature, rather than from an original sense. Our taste for fimplicity, which undoubtedly is natural, renders simple operations more agreeable than what are complex, and confequently makes them appear more natural. It de
cannot be so certain of the existence of an object in its absence, as when present.
With respect to many abstract propofitions, of which instances are above given, we have an absolute certainty and conviction of their truth, derived to us from various fenfes. We can, for example, entertain as little doubt that every thing which begins to exist must have a cause, as that the sun is in the firmament; and as little doubt that he will rise to-morrow, as that he is now set. There are many other
propositions, the truth of which is probable only, not absolutely certain; as, for example, that winter will be cold and summer warm.
That natural operations are performed in the simplest manner, is an axiom of natural philofophy: it may
be probable, but is far from being certain *