tertainment, and, we trust, the instruction of our readers, for to the reflective mind our errors are little less fraught with the latter than are our best digested speculations.

The first of these papers is a report made under the special appointment of the Medical Association of Louisiana, and was read to that body in March, 1851; the others purport to be replies to some objections which had been, raised to the views of their predecessor. Whether regarded as the declaration of faith of that body, or as the private opinions of an author of considerable reputation in the South West, they equally demand some notice at our hands.

The great contribution which our author here makes to science in the discovery of the cause of that intellectual inferiority which marks the African as compared with the European, and which the learned will be surprised to hear that he has detected in a defective oxygenation of the blood, caused by an innate antipathy in the former to fresh air, "conjoined with a deficiency of cerebral matter in the cranium, and an excess of nervous matter distributed to the organs of sensation and assimilation." The reasoning upon which this proposition is based, though dignified with the title of Baconian, evinces a more utter disregard of all the principles of a philosophical logic than it has been our fortune for some time to meet, and furnishes another melancholy example of the errors and absurdities into which even able minds may be led by the desire to establish certain pre-conceived doctrines. In the examination which we propose to give it, the words comprised in quotation marks may be disregarded, since it is in establishing and defining the relation of the other fact that our author claims originality, and upon it does he lay the greatest stress.

It may now be regarded as a well settled principle of philosophy that, in speaking of cause and effect, we mean no more than to assert a certain relation of sequence; that the presence of one thing or event will always be followed by that of the other. This sequence must, however, be not only uniform, but also unconditional. If any other fact, than the one under consideration, is necessary to the existence of the effect, this cannot be regarded as the cause, though in proportion as its presence is essential thereto it may be either a part of the cause or a mere co

existent circumstance. Thus, to borrow the very appropriate illustration furnished by Dr. Reid, day uniformly follows night, yet the latter is not said to be the cause of the former, for this sequence is not unconditional, but dependent upon the existence of another fact, viz: the appearance of the sun above the horizon. Did this last fact always exist we should have perpetual day, an approximation to which we find at the poles, where the prolonged presence or absence of the sun gives to the inhabitants of those regions a day or night of months duration. It is the presence of the luminous body, then, which produces that state which we call day, and we at once perceive that it is altogether independent of the pre-existence of darkness or night. Hence the latter is never said to be the cause, or any part of the cause, of the former. Such being the definition of cause, the problem of philosophy is to select from the vast number of antecedents of every event those with which the relation possesses these qualities, so that from the presence of the one we may confidently infer that of the other. In its investigation, a powerful instrument, is the inductive logic, and since upon it are the speculations of our author claimed to be based, and by it his reasonings conducted, it will be necessary for us to take a brief survey of its principles, and the modes of applying it, that we may the better be able to estimate the accuracy with which it has been used, and the value of the conclusions derived therefrom. As we are at present concerned only with its use in the investigation of cause and effect, we shall confine our remarks to that relation.

It is obvious, from what has been said above, that the object of inquiry in regard to any observed sequence is its uniformity and unconditional character, though the former may perhaps be comprised in the latter, for if the sequence is shown to be unconditional it cannot be otherwise than uniform. How then are we to determine that it possesses this quality? It is evident that the mere enumeration of instances, however numerous, in which we have found the facts investigated conjoined, is utterly inadequate to establish the conclusion, since so numerous are the antecedents of every event in nature that it is impossible for us, by such a process, to attribute the effect to any particular one, or to say that in the different cases before us it has

not been the consequent of several. We must, therefore, vary the circumstances, so as to eliminate as many of the antecedents as possible, without affecting the fact we are studying, when the residuum will be the cause or causes. This process of elimination, this interrogation of nature, which is so essential to the validity of our inductions, forms the great theme of the Novum Organum, that noble contribution to the philosophy of logic, to which our author is so fond of rendering a pharisaical homage, singing hallelujahs in its praise, while he utterly neglects the most fundamental of its precepts. This is pre-eminently the distinction between the Baconian philosophy and that system which, until supplanted by it, held so protracted and baneful an authority over physical science, stultifying many of the noblest intellects, and rendering futile efforts from which, if properly directed, the most splendid results might have been anticipated.

"The induction," says Lord Bacon, "which proceeds by simple. enumeration is puerile, leads to uncertain conclusions, and is exposed to danger from one contradictory instance, deciding generally from too small a number of facts, and those only the most obvious. But a really useful induction for the discovery and demonstration of the arts and sciences, should separate nature by proper rejections and exclusions, and then conclude for the affirmative after collecting a sufficient number of negatives."*

Again:

"The first work of legitimate induction, in the discovery of forms, is rejection, or the exclusive instances of individual natures, which are not found in some one instance where the given nature is present, or are found in any one instance where it is absent, or are found to increase in any one instance where the given nature decreases, or the reverse. After an exclusion correctly effected, an affirmative form will remain as the residuum, solid, true, and well defined, while all volatile opinions go off in smoke.” †

Such are the principles of this logic, and it now remains to see what regard has been paid to them by our author. We look in vain through his reasonings for those contradictory instances, upon the importance of which Lord. Bacon lays so great a stress, for we cannot regard the

requirements of this logic as by any means fulfilled by the Caucasian, between whom and the Negro there exist, according to himself, such numerous and radical distinctions, as to render any conclusion drawn therefrom altogether illusory. Instead of seeking them according to the precept of his great Master, he has closed his senses with a pertinacity which is absolutely astonishing to all facts which militate against this pet theory, constructed from the figments of an imagination even more wild and unregulated than that which has conferred an unenviable celebrity upon the cosmical theories of Whiston. Viewed as a specimen of the inductive logic, the argument briefly stated is this: All negroes sleep with their heads covered, a fact which has no existence among the Caucasian race; the former are inferior in intellect to the latter, and this inferiority is the effect of that peculiarity. Admitting, for the present, the fact stated in the first proposition to be true, the argument is in itself totally defective, since the only conclusion warranted by the premises is the coexistence of the phenomena a very different thing from the relation of cause and effect. It is evident that we are not at all advanced to a conclusion by an instance which differs from that under consideration in so many particulars, as to leave it still doubtful to which we shall refer the effect. The instances, to be of any value, must differ only in the cause and effect, so as to admit the elimination of all the other circumstances, or at least we must have instances enough to enable us to accomplish this indispensable requisite. As well might we attempt to obtain the numerical value of x from two such equations as these, x+y+z=10 and y=3, as to deduce any positive conclusion from the instances before us. That the reasoning should have been left so defective, is more surprising, when we reflect that the subject lay fully within the reach of experimental inquiry; and we are at a loss to conceive why, if truth were alone the object, that most decisive test was not resorted to. Here is a man marked with all the characteristics of the negro race, and among the rest hebetude of intellect; he sleeps with his head covered; remove the blanket, force him to breathe the free, pure air of heaven, and note the result. Would our author himself expect any invigoration of intellect from such an experiment? If not, what becomes of this

wonderful castle in the air which would regulate society by the laws of physiology? Really it is difficult to treat these crude conceits of a distempered mind with that seriousness which we have thought it most consistent with our purposes to adopt. Laying out of view the social differences between the races, which, although totally disregarded by the author, undoubtedly exercise a powerful influence, there are still numerous physical distinctions to which, for all the light thrown upon the subject by this inductive process, we would be fully as justified in attributing the effect as to that which he has selected. The negro differs from the Caucasian in having thick lips, a flat nose, curved shins, &c. Would our author refer his intellectual inferiority to either of these? If not, upon what principle is he authorized to reject these, and seek the cause in the fact, purely imaginary, as we believe, of an innate antipathy in the negro to fresh air? It is found in that process of deduction by which he has been led to his conclusion, and upon which, in his indiscriminating admiration of Lord Bacon, he has bestowed the title of induction, although, as we have shown, it lacks the essential requisites of that method.

The most superficial perusal of these articles will convince any one that the author has not arrived at his conclusions by a skilful comparison of instances, but by a process of reasoning, from what he conceives to be the law of our being. Considering oxygen as the vitalizing principle of the blood, the free access of which in a healthy condition to all the organs is essential to their proper action, he was led to infer that anything which prevented the fulfilment of either of these conditions, as regards the brain, must be attended with a corresponding hebetude of intellect. This is a deductive process, and we now proceed to test it by the canons of that method. We must remark, at the outset, that this method is applicable to the investigation of causes to but a limited extent, and can only be used in their demonstration with the utmost caution. Indeed, it is evident that we can never, by any direct á priori reasoning, arrive at the cause of any fact. He who should see the machinery of a mill at work, could never, by any direct reasoning from what lay before him, guess at the nature of the motive power. The only mode of bringing the deductive method to bear, would be to