Various - Blackwood's Edinburgh Magazine, No. CCCXXXVI. October, 1843. Vol. LIV.

But we had not intended to interpose our own lucubrations in the place of those of Mr Mill.

"Although Mr Whewell," says our author, "has naturally and properly employed a variety of phrases to bring his meaning more forcibly home, he will, I presume, allow that they are all equivalent; and that what he means by a necessary truth, would be sufficiently defined, a proposition the negation of which is not only false, but inconceivable. I am unable to find in any of Mr Whewell's expressions, turn them what way you will, a meaning beyond this, and I do not believe he would contend that they mean any thing more.

"This, therefore, is the principle asserted: that propositions, the negation of which is inconceivable, or in other words, which we cannot figure to ourselves as being false, must rest upon evidence of higher and more cogent description than any which experience can afford. And we have next to consider whether there is any ground for this assertion.

"Now, I cannot but wonder that so much stress should be laid upon the circumstance of inconceivableness, when there is such ample experience to show that our capacity or incapacity for conceiving a thing has very little to do with the possibility of the thing in itself; but is in truth very much an affair of accident, and depends upon the past habits and history of our own minds. There is no more generally acknowledged fact in human nature, than the extreme difficulty at first felt in conceiving any thing as possible, which is in contradiction to long-established and familiar experience, or even to old and familiar habits of thought. And this difficulty is a necessary result of the fundamental laws of the human mind. When we have often seen and thought of two things together, and have never, in any one instance, either seen or thought of them separately, there is by the primary law of association an increasing difficulty, which in the end becomes insuperable, of conceiving the two things apart. This is most of all conspicuous in uneducated persons, who are, in general, utterly unable to separate any two ideas which have once become firmly associated in their minds, and, if persons of cultivated intellect have any advantage on the point, it is only because, having seen and heard and read more, and being more accustomed to exercise their imagination, they have experienced their sensations and thoughts in more varied combinations, and have been prevented from forming many of these inseparable associations. But this advantage has necessarily its limits. The man of the most practised intellect is not exempt from the universal laws of our conceptive faculty. If daily habit presents to him for a long period two facts in combination, and if he is not led, during that period, either by accident or intention, to think of them apart, he will in time become incapable of doing so, even by the strongest effort; and the supposition, that the two facts can be separated in nature, will at last present itself to his mind with all the characters of an inconceivable phenomenon. There are remarkable instances of this in the history of science; instances in which the wisest men rejected as impossible, because inconceivable, things which their posterity, by earlier practice, and longer perseverance in the attempt, found it quite easy to conceive, and which every body now knows to be true. There was a time when men of the most cultivated intellects, and the most emancipated from the dominion of early prejudice, could not credit the existence of antipodes; were unable to conceive, in opposition to old association, the force of gravity acting upwards instead of downwards. The Cartesians long rejected the Newtonian doctrine of the gravitation of all bodies towards one another, on the faith of a general proposition, the reverse of which seemed to them to be inconceivable—the proposition, that a body cannot act where it is not. All the cumbrous machinery of imaginary vortices, assumed without the smallest particle of evidence, appeared to these philosophers a more rational mode of explaining the heavenly motions, than one which involved what appeared to them so great an absurdity. And they, no doubt, found it as impossible to conceive that a body should act upon the earth at the distance of the sun or moon, as we find it to conceive an end to space or time, or two straight lines inclosing a space. Newton himself had not been able to realize the conception, or we should not have had his hypothesis of a subtle ether, the occult cause of gravitation; and his writings prove, that although he deemed the particular nature of the intermediate agency a matter of conjecture, the necessity of some such agency appeared to him indubitable. It would seem that, even now, the majority of scientific men have not completely got over this very difficulty; for though they have at last learned to conceive the sun attracting the earth without any intervening fluid, they cannot yet conceive the sun illuminating the earth without some such medium.

"If, then, it be so natural to the human mind, even in its highest state of culture, to be incapable of conceiving, and on that ground to believe impossible, what is afterwards not only found to be conceivable, but proved to be true; what wonder if, in cases where the association is still older, more confirmed, and more familiar, and in which nothing even occurs to shake our conviction, or even to suggest to us any conception at variance with the association, the acquired incapacity should continue, and be mistaken for a natural incapacity? It is true our experience of the varieties in nature enables us, within certain limits, to conceive other varieties analogous to them. We can conceive the sun or moon falling, for although we never saw them fall, nor ever perhaps imagined them falling, we have seen so many other things fall, that we have innumerable familiar analogies to assist the conception; which, after all, we should probably have some difficulty in framing, were we not well accustomed to see the sun and moon move, (or appear to move,) so that we are only called upon to conceive a slight change in the direction of motion, a circumstance familiar to our experience. But when experience affords no model on which to shape the new conception, how is it possible for us to form it? How, for example, can we imagine an end to space and time? We never saw any object without something beyond it, nor experienced any feeling without something following it. When, therefore, we attempt to conceive the last point of space, we have the idea irresistibly raised of other points beyond it. When we try to imagine the last instant of time, we cannot help conceiving another instant after it. Nor is there any necessity to assume, as is done by the school to which Mr Whewell belongs, a peculiar fundamental law of the mind to account for the feeling of infinity inherent in our conception of space and time; that apparent infinity is sufficiently accounted for by simple and universally acknowledged laws."—Vol. I. p. 313.

Mr Mill does not deny that there exists a distinction, as regards ourselves, between certain truths (namely, that of some, we cannot conceive them to be other than truths,) but he sets no value on this distinction, inasmuch as there is no proof that it has its counterpart in things themselves; the impossibility of a thing being by no means measured by our inability to conceive it. And we may observe, that Mr Whewell, in consistency with the metaphysical doctrine upon space and time which he has borrowed from Kant, ought, under another shape, to entertain a similar doubt as to whether this distinction represent any real distinction in the nature of things. He considers, with Kant, that space is only that form with which the human mind invests things—that it has no other than this merely mental existence—is purely subjective. Presuming, therefore, that the mind is, from its constitution, utterly and for ever unable to conceive the opposite of certain truths, (those, for instance, of geometry;) yet as the existence of space itself is but a subjective truth, it must follow that all other truths relating to it are subjective also. The mind is not conversant with things in themselves, in the truths even of geometry; nor is there any positive objective truth in one department of science more than another. Mr Whewell, therefore, though he advocates this distinction between necessary and contingent truth with a zeal which would seem to imply that something momentous, or of peculiar interest, was connected with it, can advocate it only as a matter of abstract metaphysical science. He cannot participate in that feeling of exaltation and mystery which has led many to expatiate upon a necessary and absolute truth which the Divine Power itself cannot alter, which is equally irresistible, equally binding and compulsory, with God as with man. Of this spirit of philosophical enthusiasm Mr Whewell cannot partake. Space and Time, with all their properties and phenomena, are but recognized as the modes of thought of a human intelligence.