| Every effect necessarily pre-supposes a cause; effect being a relative term, of which cause is the correlative. |
| But this does not prove, that every being must be preceded by a cause; no more than it follows, because every husband must have a wife, that therefore every man must be marryed. |
| The true state of the question is, whether every object, which begins to exist, must owe its existence to a cause: and this I assert neither to be intuitively nor demonstratively certain, and hope to have proved it sufficiently by the foregoing arguments. |
| Since it is not from knowledge or any scientific reasoning, that we derive the opinion of the necessity of a cause to every new production, that opinion must necessarily arise from observation and experience. |
| The next question, then, should naturally be, how experience gives rise to such a principle? But as I find it will be more convenient to sink this question in the following, Why we conclude, that such particular causes must necessarily have such particular erects, and why we form an inference from one to another? we shall make that the subject of our future enquiry. |
| It will, perhaps, be found in the end, that the same answer will serve for both questions. |
| SECT. IV. OF THE COMPONENT PARTS OF OUR REASONINGS CONCERNING CAUSE AND EFFECT. |
| Though the mind in its reasonings from causes or effects carries its view beyond those objects, which it sees or remembers, it must never lose sight of them entirely, nor reason merely upon its own ideas, without some mixture of impressions, or at least of ideas of the memory, which are equivalent to impressions. |
| When we infer effects from causes, we must establish the existence of these causes; which we have only two ways of doing, either by an immediate perception of our memory or senses, or by an inference from other causes; which causes again we must ascertain in the same manner, either by a present impression, or by an inference from their causes, and so on, till we arrive at some object, which we see or remember. |
| It is impossible for us to carry on our inferences IN INFINITUM; and the only thing, that can stop them, is an impression of the memory or senses, beyond which there is no room for doubt or enquiry. |
| To give an instance of this, we may chuse any point of history, and consider for what reason we either believe or reject it. |
| Thus we believe that Caesar was killed in the senate-house on the ides of March; and that because this fact is established on the unanimous testimony of historians, who agree to assign this precise time and place to that event. |
| Here are certain characters and letters present either to our memory or senses; which characters we likewise remember to have been used as the signs of certain ideas; and these ideas were either in the minds of such as were immediately present at that action, and received the ideas directly from its existence; or they were derived from the testimony of others, and that again from another testimony, by a visible gradation, it will we arrive at those who were eyewitnesses and spectators of the event. |
| It is obvious all this chain of argument or connexion of causes and effects, is at first founded on those characters or letters, which are seen or remembered, and that without the authority either of the memory or senses our whole reasoning would be chimerical and without foundation. |
| Every link of the chain would in that case hang upon another; but there would not be any thing fixed to one end of it, capable of sustaining the whole; and consequently there would be no belief nor evidence. |
| And this actually is the case with all hypothetical arguments, or reasonings upon a supposition; there being in them, neither any present impression, nor belief of a real existence, |
| I need not observe, that it is no just objection to the present doctrine, that we can reason upon our past conclusions or principles, without having recourse to those impressions, from which they first arose. |
| For even supposing these impressions should be entirely effaced from the memory, the conviction they produced may still remain; and it is equally true, that all reasonings concerning causes and effects are originally derived from some impression; in the same manner, as the assurance of a demonstration proceeds always from a comparison of ideas, though it may continue after the comparison is forgot. |
| SECT. V. OF THE IMPRESSIONS OF THE SENSES AND MEMORY. |
| In this kind of reasoning, then, from causation, we employ materials, which are of a mixed and heterogeneous nature, and which, however connected, are yet essentially different from each other. |
| All our arguments concerning causes and effects consist both of an impression of the memory or, senses, and of the idea of that existence, which produces the object of the impression, or is produced by it. |