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requires to be peculiarly impressed on them, namely, to acquaint themselves, in some moderate degree, with the general nature of the subject, before they adduce detached points of objection as fatal to the whole train of conclusions.

To take, however, an instance of the kind of objection alluded to: one geologist dwells on the uncertainty attending a positive distinction of particular formations from their mineral characters alone, and insists on the attainment of certainty only from their characteristic fossil remains. Another remarks that, in some particular cases, considerable ambiguity attaches to the determination of fossil remains, and that those really belonging to different formations may, in some instances, be confounded together. Hence the objector contends that the argument " halts on both its legs," and triumphs in his inference that there can be no certainty at all in the science! In other words, because either source of evidence alone may be defective, therefore both together cannot be satisfactory. Or again, because, in some instances, there may be confessed ambiguities in the interpretation, therefore in no case can there be any certainty. A passage is sometimes cited from Cuvier's account of his researches on fossil bones, in which he, with all the caution of a true philosopher, carefully insists on all the sources of fallacy by which his inquiries were liable to be affected; and speaks, with becoming modesty, of his conclusions, as often being far removed from the evidence of demonstration. And this is then construed by the sceptic into a confession that the whole science has no solid foundation, and is little more than a system of gratuitous hypotheses !

It would be useless to dwell further on such speculations. I should not, perhaps, have noticed them at all, had they not recently received a certain stamp of respectability from their association with the name of a writer of old repute,

who has thought it necessary, at the present day, to reappear in a field so different from that of moral and religious discussion, in which his former distinction might have given weight to his opinions: I allude to a pamphlet entitled, Considerations on Modern Theories of Geology, &c., by T. GISBORNE, M.A., Prebendary of Durham. London, 1837. This is surely not an age in which dignitaries of the Church should be found arraying themselves in hostility to


NOTE C. p. 87.

LORD BROUGHAM in his Discourse on Natural Theology, in a note on Cause and Effect, after stating the nature, and upholding the soundness (as far as it goes,) of Hume's doctrine of causation, yet contends that something more is necessary to a complete view of the subject. Besides the notion of invariable sequence, he maintains we have also a "belief that the one event occasions the other; that there is between the two a connexion beyond the mere relation of junction and sequence, and that the preceding event exerts an influence, a force, a power, over the other, and produces the other."-p. 228.

And the grounds of this belief, he contends, are to be found in the proofs, 1st, of the invariable sequence; 2nd, of the condition that "not only must the second event always have been found to follow the first, but the second must never have been observed without the first preceding it, or at least without some other preceding it, in which case the causation is predicated alike of both these preceding events."-p. 229.

Or, in fewer words, we must prove "that one event

always follows the other, and that it ceases when the other ceases." But besides this, 3d, "Our minds form, whether we will or no, another idea, not merely that of constant connexion or succession, but of the one exerting a power over the other by an inherent force; and this is the idea of causation. Whence do we derive it? I apprehend only from our consciousness. We feel that we have a will and a

power," &c.

He then traces the effects originating in our volition which we can produce on material objects around us, and contends that we hence form our notion of causation as above defined. That we do thus obtain an idea of causation is, I conceive, perfectly unquestionable; but it refers solely to one species: viz., that which by our voluntary agency produces effects on matter subject to us; or what I have termed moral causation. The author does not pursue this point any further, so as to show how or whether at all the notion applies to physical causes and effects. This is what I have attempted to do above. We transfer the idea by a fair analogy to other cases of animal power, and to instances in which we trace the marks of intelligence; but only by a vague, imaginary, and delusive one, to the succession of physical events, or their dependence one on another.

The author proceeds to discuss the idea of necessary connexion which (in the sense of à priori necessity,) is certainly excluded by this view of causes; since "the whole is a question of fact, of contingent truth." But he maintains that "our ideas of power and of causation are solid and well-founded, although they only refer to a power or a causation which may or may not exist." In this I entirely concur, especially when viewed in connexion with the distinctions here laid down.

NOTE D. p. 120.

THE achromatism of the eye is a subject which has occasioned much discussion, and that of a remarkable kind. The most eminent optical writers have been directly opposed in opinion as to the fact. And those who have admitted the fact, have yet held it unaccountable, and have sought indirect explanations of it as being, strictly speaking, impossible in theory.

I have (as I believe for the first time,) shown that it is perfectly possible in theory, whilst it may or may not be the fact in different individual cases. I mention this the more as the drift of my investigations have been strangely misconceived by some. They are given in one of the series of tracts printed by the Oxford Ashmolean Society: On the Achromatism of the Eye. Oxford, 1834. See also London and Edinburgh Journal of Science, April 1835.

NOTE E. p. 121.

THE extreme confusion which has been introduced into discussions of this nature, owing to the ambiguity of the term "cause," has been ably exposed by several writers. The same point has been dwelt upon by Mr. Irons, [On Final Causes, p. 53,] who has examined largely the various opinions of ancient and modern writers on the subject, and has discussed the views of Hume and others with regard to the nature of causation. With so extensive a knowledge of philosophical authors, (to judge from his quotations,) it seems strange that he has omitted all reference to the

physical part of the subject, and has not been led to the distinction on which I have so particularly dwelt between the physical and the moral senses of the term "cause.” He has, in fact, confined himself throughout to the idea of an operative agency, or what I have called "moral causation;" and considers all idea of causation as including that of an efficient influence; defining a cause to be "that which of itself makes any thing begin to be," (pp. 74, 79, &c.,) and which is, in fact, intelligence.

Proceeding, then, on such an idea of causes, and omitting all reference to the great argument from physical causes, in the sense in which I have explained them, it is not surprising that this author should disparage to the uttermost the argument from final causes, of which he takes so unhappily contracted a view. He has, however, clearly distinguished the boundary between our knowledge of the bare fact of fitness or adjustment in created beings and their properties, and the inference of design and intelligence. The former, he shows, was the strict sense in which alone the ancient philosophers spoke of "final causes." Among other points, he particularly refers (p. 125,) to a circumstance related by Mr. Campbell, the missionary; that on showing a watch to some savages, they were by no means able to infer design; this example has, in fact, been much dwelt upon, and regarded as decisive against the efficiency of Paley's argument. But I would ask were the savages able to reason in any other case? or to make inferences at all? This must obviously be shown before the case can be of the slightest avail to the argument. Paley, I apprehend, never contemplated the reasoning as addressed to savages.

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