It may perhaps be found that the human mind is not capable of arriving at absolute certainty upon any subject of enquiry; and it must be admitted that human science is attended with all degrees of certainty, from the highest moral evidence to the slightest balance of probability. But human beings are capable of apprehending and weighing all these degrees; and to know the exact quantity of probability which I ought to ascribe to any proposition may be said to be in one sense the possessing certain knowledge.
It would further be absurd, if we regard truth in relation to its empire over our conduct, to suppose that it is not limited in its operations by the faculties of our frame. It may be compared to a connoisseur who, however consummate be his talents, can extract from a given instrument only such tones as that instrument will afford. But, within these limits, the deduction which forms the principal substance of this chapter proves to us that whatever is brought home to the conviction of the understanding, so long as it is present to the mind, possesses an undisputed empire over the conduct. Nor will he who is sufficiently conversant with the science of intellect be hasty in assigning the bounds of our capacity. There are some things which the structure of our bodies will render us forever unable to effect; but in many cases the lines which appear to prescribe a term to our efforts will, like the mists that arise from a lake, retire further and further, the more closely we endeavour to approach them.
Fourthly, the vices and moral weakness of man are not invincible. This is the preceding proposition with a very slight variation in the statement.
Vice and weakness are founded upon ignorance and error; but truth is more powerful than any champion that can be brought into the field against it;Chapter onsequently truth has the faculty of expelling weakness and vice, and placing nobler and more beneficent principles in their stead.
Lastly, man is perfectible. This proposition needs some explanation.
By perfectible, it is not meant that he is capable of being brought to perfection. But the word seems sufficiently adapted to express the faculty of being continually made better and receiving perpetual improvement; and in this sense it is here to be understood. The term perfectible, thus explained, not only does not imply the capacity of being brought to perfection, but stands in express opposition to it. If we could arrive at perfection, there would be an end to our improvement. There is however one thing of great importance that it does imply: every perfection or excellence that human beings are competent to conceive, human beings, unless in cases that are palpably and unequivocally excluded by the structure of their frame, are competent to attain.
This is an inference which immediately follows from the omnipotence of truth. Every truth that is capable of being communicated is capable of being brought home to the conviction of the mind. Every principle which can be brought home to the conviction of the mind will infallibly produce a correspondent effect upon the conduct. If there were not something in the nature of man incompatible with absolute perfection, the doctrine of the omnipotence of truth would afford no small probability that he would one day reach it. Why is the perfection of man impossible?
The idea of absolute perfection is scarcely within the grasp of human understanding. If science were more familiarized to speculations of this sort, we should perhaps discover that the notion itself was pregnant with absurdity and contradiction.
It is not necessary in this argument to dwell upon the limited nature of the human faculties. We can neither be present to all places nor to all times. We cannot penetrate into the essences of things, or rather we have no sound and satisfactory knowledge of things external to ourselves, but merely of our own sensations. We cannot discover the causes of things, or ascertain that in the antecedent which connects it with the consequent, and discern nothing but their contiguity. With what pretence can a being thus shut in on all sides lay claim to absolute perfection?
But, not to insist upon these considerations, there is one principle in the human mind which must forever exclude us from arriving at a close of our acquisitions and confine us to perpetual progress. The human mind so far as we are acquainted with it, is nothing else but a faculty of perception.
All our knowledge, all our ideas everything we possess as intelligent beings, comes from impression. All the minds that exist set out from absolute ignorance.
They received first one impression, and then a second. As the impressions became more numerous, and were stored by the help of memory, and combined by the faculty of association, so the experience increased, and with the experience the knowledge, the wisdom, everything that distinguishes man from what we understand by a "clod of the valley." This seems to be a simple an incontrovertible history of intellectual being; and, if it be true, then as our accumulations have been incessant in the time that is gone, so, as long as we continue to perceive, to remember or reflect, they must perpetually increase.