and the flowers of saffron that of the like itself. If it was not one kind of bile." The early speculations respecting the chemical composition of bodies were rendered abortive by no circumstance more than by their invariably taking for granted that the properties of the elements must resemble those of the compounds which were formed from them. motion, it must be another. In like manner it was supposed that the physical qualities of objects must arise from some similar quality, or perhaps only some quality bearing the same name, in the particles or atoms of which the objects were composed; that a sharp taste, for example, must arise from sharp parTo descend to more modern in- ticles. And reversing the inference, stances; it was long thought, and the effects produced by a phenomenon was stoutly maintained by the Carte-must, it was supposed, resemble in sians, and even by Leibnitz, against their physical attributes the phenothe Newtonian system, (nor did New-menon itself. The influences of the ton himself, as we have seen, contest planets were supposed to be analothe assumption, but eluded it by an gous to their visible peculiarities: arbitrary hypothesis,) that nothing Mars, being of a red colour, portended (of a physical nature at least) could fire and slaughter, and the like. account for motion except previous Passing from physics to metamotion; the impulse or impact of physics, we may notice among the some other body. It was very long most remarkable fruits of this à before the scientific world could pre-priori fallacy two closely analogous vail upon itself to admit attraction theories, employed in ancient and and repulsion (i.e. spontaneous ten-modern times to bridge over the dencies of particles to approach or chasm between the world of mind recede from one another) as ultimate and that of matter: the species senlaws, no more requiring to be ac-sibiles of the Epicureans, and the counted for than impulse itself, if indeed the latter were not, in truth, resolvable into the former. From the same source arose the innumerable hypotheses devised to explain those classes of motion which appeared more mysterious than others because there was no obvious mode of attributing them to impulse; as, for example, the voluntary motions of the human body. Such were the interminable systems of vibrations propagated along the nerves, or animal spirits rushing up and down between the muscles and the brain, which, if the facts could have been proved, would have been an important addition to our knowledge of physiological laws; but the mere invention or arbitrary supposition of them could not, unless by the strongest delusion, be supposed to render the phenomena of animal life more comprehensible or less mysterious. Nothing, however seemed satisfactory but to make out that motion was caused by motion; by something modern doctrine of perception by means of ideas. These theories are, indeed, probably, indebted for their existence not solely to the fallacy in question, but to that fallacy combined with another natural prejudice already adverted to, that a thing cannot act where it is not. In both doctrines it is assumed that the phenomenon which takes place in us when we see or touch an object, and which we regard as an effect of that object, or rather of its presence to our organs, must of necessity resemble very closely the outward object itself. To fulfil this condition, the Epicureans supposed that objects were constantly projecting in all directions impalpable images of themselves, which entered at the eyes and penetrated to the mind; while modern metaphysicians, though they rejected this hypothesis, agreed in deeming it necessary to suppose that not the thing itself, but a mental image or representation of it, was the direct object of perception. Dr. Reid had to employ a world of argument and illustration to familiarise people with the truth that the sensations or impressions on our minds need not necessarily be copies of, or bear any resemblance to, the causes which produce them; in opposition to the natural prejudice which led people to assimilate the action of bodies upon our senses, and through them upon our minds, to the transfer of a given form from one object to another by actual moulding. The works of Dr. Reid are even now the most effectual course of study for detaching the mind from the prejudice of which this was an example. And the value of the service which he thus rendered to popular philosophy is not much diminished although we may hold, with Brown, that he went too far in imputing the "ideal theory," as an actual tenet, to the generality of the philosophers who preceded him, and especially to Locke and Hume; for if they did not themselves consciously fall into the error, unquestionably they often led their readers into it. it is here used simply for those no- 66 I have given a variety of instances in which the natural prejudice, that The prejudice that the conditions causes and their effects must resemble of a phenomenon must resemble the one another, has operated in practice phenomenon is occasionally exagger- so as to give rise to serious errors. I ated, at least verbally, into a still shall now go further, and produce more palpable absurdity; the condi- from writings even of the present or tions of the thing are spoken of as if very recent times, instances in which they were the very thing itself. In this prejudice is laid down as an esBacon's model inquiry, which occu- tablished principle. M. Victor Coupies so great a space in the Novum sin, in the last of his celebrated lecOrganum, the inquisitio in formam tures on Locke, enunciates the maxim calidi, the conclusion which he fav- in the following unqualified terms: ours is that heat is a kind of motion; "Tout ce qui est vrai de l'effet, est meaning of course not the feeling of vrai de la cause." A doctrine to which, heat, but the conditions of the feel- unless in some peculiar and technical ing; meaning, therefore, only that meaning of the words cause and effect, whenever there is heat, there must it is not to be imagined that any perfirst be a particular kind of motion; son would literally adhere; but he who but he makes no distinction in his could so write must be far enough from language between these two ideas, seeing that the very reverse might expressing himself as if heat, and the be the effect; that there is nothing conditions of heat, were one and the impossible in the supposition that no same thing. So the elder Darwin, in one property which is true of the effect the beginning of his Zoonomia, says, might be true of the cause. Without "The word idea has various mean-going quite so far in point of expresings in the writers of metaphysics: sion, Coleridge, in his Biographia Lite raria,* affirms as an "evident truth," | scarcely a parody to say, that if there that "the law of causality holds only be pepper in the soup there must be between homogeneous things, i.e. pepper in the cook who made it, since things having some common pro- otherwise the pepper would be withperty," and therefore "cannot extend out a cause. A similar fallacy is comfrom one world into another, its op- mitted by Cicero in his second book posite :" hence, as mind and matter De Finibus, where, speaking in his have no common property, mind can- own person against the Epicureans, not act upon matter, nor matter upon he charges them with inconsistency mind. What is this but the à priori in saying that the pleasures of the fallacy of which we are speaking? mind had their origin from those of The doctrine, like many others of the body, and yet that the former Coleridge, is taken from Spinoza, in were more valuable, as if the effect the first book of whose Ethica (De could surpass the cause. "Animi Deo) it stands as the Third Proposi- voluptas oritur propter voluptatem tion, "Quæ res nihil commune inter corporis, et major est animi voluptas se habent, earum una alterius causa quam corporis? ita fit ut gratulator, esse non potest," and is there proved lætior sit quam is cui gratulatur." from two so-called axioms, equally Even that, surely, is not an imposgratuitous with itself; but Spinoza, sibility: a person's good fortune has ever systematically consistent, pur- often given more pleasure to others sued the doctrine to its inevitable than it gave to the person himself. consequence, the materiality of God. The same conception of impossibility led the ingenious and subtle mind of Leibnitz to his celebrated doctrine of a pre-established harmony. He, too, thought that mind could not act upon matter, nor mat ter upon mind, and that the two, therefore, must have been arranged by their Maker like two clocks, which, though unconnected with one another, strike simultaneously, and always point to the same hour. Malebranche's equally famous theory of Occasional Causes was another form of the same conception instead of supposing the clocks originally arranged to strike together, he held that when the one strikes, God interposes, and makes the other strike in correspondence with it. Descartes, in like manner, whose works are a rich mine of almost every description of à priori fallacy, says that the Efficient Cause must at least have all the perfections of the effect, and for this singular reason: "Si enim ponamus aliquid in ideâ reperiri quod non fuerit in ejus causâ, hoc igitur habet a nihilo; " of which it is * Vol. i. chap. 8. Descartes, with no less readiness, applies the same principle the converse way, and infers the nature of the effects from the assumption that they must, in this or that property or in all their properties, resemble their cause. To this class belong his speculations, and those of so many others after him, tending to infer the order of the universe, not from observation, but by à priori reasoning from supposed qualities of the Godhead. This sort of inference was probably never carried to a greater length than it was in one particular instance by Descartes, when, as a proof of one of his physical principles, that the quantity of motion in the universe is invariable, he had recourse to the immutability of the Divine Nature. Reasoning of a very similar character is, however, nearly as common now as it was in his time, and does duty largely as a means of fencing off disagreeable conclusions. Writers have not yet ceased to oppose the theory of divine benevolence to the evidence of physical facts, to the principle of population, for example. And people seem in general to think that they have used a very powerful argument when they have said, that to suppose glecting facts or particulars which ought to have been observed. It is mal-observation when something is not simply unseen, but seen wrong; when the fact or phenomenon, instead of being recognised for what it is in reality, is mistaken for something else. some proposition true, would be a re- It is non-observation when all the flection on the goodness or wisdom error consists in overlooking or neof the Deity. Put into the simplest possible terms, their argument is, "If it had depended on me, I would not have made the proposition true, therefore it is not true." Put into other words it stands thus: "God is perfect, therefore (what I think) perfection must obtain in nature. But since in reality every one feels that nature is very far from perfect, the doctrine is never applied consistently. It furnishes an argument which (like many others of a similar character) people like to appeal to when it makes for their own side. Nobody is convinced by it, but each appears to think that it puts religion on his side of the question, and that it is a useful weapon of offence for wounding an adversary. Although several other varieties of à priori fallacy might probably be added to those here specified, these are all against which it seems necessary to give any special caution. Our object is to open, without attempting or affecting to exhaust, the subject. Having illustrated, therefore, this first class of Fallacies at sufficient length, I shall proceed to the second. CHAPTER IV. FALLACIES OF OBSERVATION. § I. FROM the fallacies which are properly Prejudices, or presumptions antecedent to, and superseding procf, we pass to those which lie in the incorrect performance of the proving process. And as Proof, in its widest extent, embraces one or more, or all, of three processes, Observation, Generalisation, and Deduction, we shall consider in their order the errors capable of being committed in these three operations. And first, of the first mentioned. § 2. Non-observation may either take place by overlooking instances, or by overlooking some of the circumstances of a given instance. If we were to conclude that a fortuneteller was a true prophet, from not adverting to the cases in which his predictions had been falsified by the event, this would be non-observation of instances; but if we overlooked or remained ignorant of the fact that in cases where the predictions had been fulfilled, he had been in collusion with some one who had given him the information on which they were grounded, this would be non-observation of circumstances. The former case, in so far as the act of induction from insufficient evidence is concerned, does not fall under this second class of Fallacies, but under the third, Fallacies of Generalisation. In every such case, however, there are two defects or errors instead of one there is the error of treating the insufficient evidence as if it were sufficient, which is a Fallacy of the third class; and there is the insufficiency itself, the not having better evidence; which, when such evidence, or, in other words, when other instances, were to be had, is Nonobservation; and the erroneous inference, so far as it is to be attributed to this cause, is a Fallacy of the second class. It belongs not to our purpose to treat of non-observation as arising from casual inattention, from general slovenliness of mental habits, want of A fallacy of misobservation may due practice in the use of the observ. be either negative or positive; either ing faculties, or insufficient interest Non-observation or Mal-observation. in the subject. The question per tinent to logic is-Granting the want of complete competency in the observer, on what point is that insufficiency on his part likely to lead him wrong? or rather, what sorts of instances, or of circumstances in any given instance, are most likely to escape the notice of observers generally-of mankind at large. the languages of Europe," viz. “Fortune favours fools." He ascribes it partly to the "tendency to exaggerate all effects that seem disproportionate to their visible cause, and all circumstances that are in any way strongly contrasted with our notions of the persons under them." Omitting some explanations which would refer the error to mal-observation or to the other species of non-observation, (that of circumstances,) I take up the quo § 3. First, then, it is evident that when the instances on one side of a question are more likely to be remem-tation farther on. "Unforeseen cobered and recorded than those on the other, especially if there be any strong motive to preserve the memory of the first, but not of the latter, these last are likely to be overlooked, and escape the observation of the mass of mankind. This is the recognised explanation of the credit given, in spite of reason and evidence, to many classes of impostors to quack doctors and fortune-tellers in all ages, to the "cunning man " of modern times, and the oracles of old. Few have considered the extent to which this fallacy operates in practice, even in the teeth of the most palpable negative evidence. A striking example of it is the faith which the uneducated portion of the agricultural classes, in this and other countries, continue to repose in the prophecies as to weather supplied by almanac-makers, though every season affords to them nume rous cases of completely erroneous prediction; but as every season also furnishes some cases in which the prediction is fulfilled, this is enough to keep up the credit of the prophet with people who do not reflect on the number of instances requisite for what we have called, in our inductive terminology, the Elimination of Chance; since a certain number of casual coincidences not only may, but will happen, between any two unconnected events. Coleridge, in one of the essays in the Friend, has illustrated the matter we are now considering, in discussing the origin of a proverb, "which, differently worded, is to be found in all incidences may have greatly helped a |