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On the nature, diversity, and limits of Evidence.
THAT positive and actual existence must be the original source of all evidence, and the real fountain of all knowledge, that evidence must be always derived from_existence, and, that it is not possible for existence to be derived from evidence, is matter of intuitive conviction. No mathematical demonstration can be rendered more obvious or more convincing to the senses, than is the truth of the foregoing propositions to the human understanding.
It is, at the same time, equally demonstrable, that positive and real existence must uniformly and of necessity imply the evidence of existence, that it is not possible for any thing to exist, without affording by its own existence, the best, and indeed the only legitimate evidence of its being; and, lastly, that all legitimate evidence must be derived either immediately or mediately from real and positive existence. The truth of the foregoing propositions is so perfectly intuitive, that no man ever yet attempted to ascribe either evidence or knowledge to any other source than that of actual or relative existence, except by asserting the unorigination and eternity of knowledge; which would clearly amount to this at the last, viz. that if real existence be not the real origin of evidence and knowledge, knowledge and evidence must be absolutely unoriginated.
Every thing in actual existence, must of necessity be under the immediate cognizance of the Deity, and therefore the primitive sources of all knowledge must be always accessible to his infinite mind. It might, indeed, be presumed, in relation to all created beings, that every act of creation itself must of necessity imply in the Deity both a perception of its existence, and a perfect knowledge of its nature and
its properties; and yet it is not with the act of creating such beings, but with the fact of their existence, that we must associate the knowledge of their natures and properties. In the order of time, the fact of their existence and the knowledge of their natures and properties, are coeval and coexistent; but in the order of nature, the fact of their existence is consequent to the act which gave them their being, and the knowledge of their existence and nature, is as consequent to the fact of their actual existence. The real difference in all such cases, lies between the act of creation, in the process of its operation, and created production revealed in complete and formal existence.
The evidence of potentiality, is not, in reality, a different evidence from that of actual existence, whether it be applied to the Deity, or to finite beings; inasmuch as all potentiality has an actual existence in all beings, whether finite or infinite, to whom it may respectively belong. Power in actual operation, and power in the state of latent ability, are equally real and equally in being: so that even the knowledge of possibilities, must, in reality, rest upon fact, and upon the permanent basis of actual existence.
The evidence of purpose, in like manner, is, in reality, the evidence of fact and actual existence; for although mental purposes have only a relative existence, yet in the beings who are the authors of these purposes, the purposes themselves have as real an existence as the beings who formed them. It therefore of necessity will follow, in relation even to mental purposes, that their evidence must be derived from their actual existence, and that their existence alone is the native source of all the evidence of their being.
Prescience, or foreknowledge, can have only a relative bearing upon the objects of its anticipation; it cannot imply that some future thing does now actually exist; but only that some future thing will hereafter probably or certainly transpire, in consequence of some known cause which is at present in actual existence. The knowledge therefore is of something in actual existence, and the prescience is of something that will hereafter probably or certainly transpire: but the prescience is derived from precisely the same source as the knowledge; only the evidence in the one case is mediate, and in the other it is immediate. Evidence therefore is uniformly derived from actual existence,
whether the inquiry be instituted concerning fact or potentiality, or mental purpose: and if the doctrine of an unoriginated and eternal prescience, be not supported by the evidence of actual existence presented under one of its forms, or deduced by infallible inference from actual existence, the theory must of necessity fall to the ground.
Knowledge, in all finite beings, and particularly in human beings, must of necessity be limited, because their access to the primitive sources of evidence is exceedingly partial. But although their real and positive knowledge must be confined within the range of their own personal and actual observation, or, in other words, to their means of access to the primitive evidence of things; yet there is a knowledge of a secondary order, which is excogitated by the labour of their own minds, in the way of mental deduction from primitive evidence; and there is a knowledge of a third order, which is derived from the testimony of others, and is therefore denominated faith. But it is easy to perceive, or rather, it is almost impossible not to discern, that both deduction and faith must be originally derived from actual and immediate observation, which is the native and primary evidence of all existence. The original sources of human knowledge are three only, viz. that of our animal senses, that of mental deduction, and that of testimony or faith.
The evidence of our animal senses has been divided into mathematical demonstration, and sensible proof; and they have been placed in this order, because it has been said, that mathematical demonstration cannot possibly deceive us, but that sensible proof may be sometimes illusive.
Mathematical demonstration is effected by the introduction of a rule or medium between the premises and the conclusions for the purpose of giving precision and truth to our investigations: as when, by the actual introduction of four different objects, we demonstrate that two and two put together make the sum of four; and by the application of a pair of compasses to two different diagrams, we demonstrate that, the three angles of an equilateral triangle are equal to two right angles. But when these and other problems have been once solved by an actual experiment, the mind can easily recal the ideas, and repeat the experiment by a mental operation.
It has indeed been asserted, that our senses may possibly
deceive us; as when we mistake the real magnitude or distance of visible and distant objects; but then it is to be remembered that the error, in such cases, does not belong to the notices of the senses, but to the mental deduction which the mind infers from those notices. The sense of heat and cold, and the perception and impression of external objects are as real and correct as any mathematical diagram, but the inferences which the mind deduces from such premises are sometimes drawn without the interposition of a process, like that of mathematical demonstration, and are therefore liable to be erroneous. But the possibility of forming an erroneous judgment, where we either neglect or have not the means of applying a test like that of mathematical demonstration, does by no means invalidate the evidence of our senses; because every mathematical demonstration is, after all, nothing more than sensible proof.
The second division of evidence is that of mental deduction, which not only applies to all scientific ratiocination, but it equally applies to all mental and moral intuition.
Mental deduction is of two kinds; and is either synthetical, which implies the summing up of particulars into one general amount; or it is analytical, which implies the separation of general truths into the particulars of which they are composed. In this department of evidence, all correct thinking amounts to mental demonstration, inasmuch as things equally understood must be equally plain, and equally demonstrable. All cases that will admit of mental demonstration, are cases of absolute certainty, and are as infallible as any mathematical demonstration can possibly be rendered. Locke has said, that, "Where the agreement or disagreement of any thing is plainly and clearly perceived, it is called demonstration." And Glanville has said, "The grand articles of our belief, are as demonstrable as geometry."
That mere negation could not have produced any positive existence is a matter of mental deduction, and it is as obvious as it is certain: and that this material world could not have bestowed upon itself the gift of existence, is equally demonstrable that since, at the present moment, something is in actual existence, something must always have been in existence; and that all finite existence must owe its being
to an infinite cause, is as demonstrable as any mathematical problem can possibly be rendered. It is true the Apostle has said, that " Through faith we understand that the worlds were framed by the word of God." That the world must have been created, by some means, is a subject of mental intuition, and absolute certainty; but that the worlds were made by the word of God; that He said, "Let there be light, and there was light," is not within the limits of mental deduction, but it has been made known to mankind by a revelation from heaven. The Apostle also inculcates, that "Through faith we understand that things which are seen were not made of things which do appear." Although it is intuitively certain that the matter of which this world is composed, could not have been eternal; yet, whether the matter of which this world is composed was original or renovated, could never have been discovered by the human mind; and therefore it is by faith we understand that the things which are seen were not made of things which do appear.
One species of mental certainty may be denominated moral intuition, in which we perceive, by immediate conviction, the moral truth or falsehood of any proposition, and that without any formal process of ratiocination. As, for instance, that an infinite being must be absolutely perfect, and alike incapable of physical, mental, and moral error: or that, if all moral actions, and the final issue of human life be the objects of a certain prescience, it is not possible for either of them to be contingent, or for human beings to be morally free.
The third and last division of evidence is, the evidence of testimony, which, if the testimony be valid, must be derived originally from the primitive source of all evidence, even from actual and real existence, although it may be delivered either by the original observer, or by any subsequent and subordinate testator. In such cases, the fact or doctrine which is testified or asserted, may itself be correct, and true, and certain; but the evidence afforded testimony of that fact or doctrine is of an inferior order to that of sensible proof, and inferior to that of mental deduction. Sensible proof and mental deduction, are both of the nature of absolute certainty; but the evidence of testimony can never arrive at a certain evidence, because it will always be pos