Chapter 51

FALLACIES OF SIMPLE INSPECTION; OR, À PRIORI FALLACIES.

There must be some _à priori_ knowledge, some propositions to be received without proof; for there cannot be a chain suspended from nothing. What these are is disputed, one school recognising as ultimate premisses only the facts of our subjective consciousness, e.g. Sensations, while Ontologists hold that the mind intuitively, and not through experience, recognises as realities other existences, e.g. Substances, which are suggested by, though not inferrible from, those facts of consciousness. But, as both schools, in fact, allow that the mind infers the _reality_ from the _idea_ of a thing, and that it may do this unduly, there results a class of Fallacies resting on the tacit assumption that the objects in nature have the same order as our ideas of them. Hence not only arose the vulgar belief that facts which make us think of an event are omens foreboding (e.g. lucky or unlucky names), or even causing its occurrence; but even men of science both did and do fall into this Fallacy. The following dogmas express the different forms of this error:--

1. [Greek: a]. _Things which we cannot help thinking of together must coexist_; thus Descartes held that, because existence is involved (though really only by the thinker himself) in the idea of a geometrical figure, a thing like the idea must exist. [Greek: b]. _Whatever is inconceivable is false._ The latter proposition has been defended by drawing a distinction between the principle, and its possibly wrong application to facts, e.g. to Antipodes; but how can we ever know that it has been rightly applied? Coleridge, again, has distinguished between the unimaginable, which he thinks may possibly be true, and the inconceivable, which he thinks cannot be; but Antipodes were imaginable at the same period when they were inconceivable. In fact, as even to Newton it seemed inconceivable, that a thing should act where it is not (e.g. that the sun should act upon the earth without the medium of an ether), simply because his mind was not familiar with the idea, so it _may_ be with _our_ incapability (if not, indeed, resulting merely from our limited faculties) of _conceiving_, e.g. that matter cannot think; that space is infinite; that _ex nihilo nihil fit_. Leibnitz's tenet that all _natural_ phenomena must be explicable _à priori_, and the further assumption by some that Nature always acts by the simplest, i.e. by the most easily conceivable means (and that, therefore, e.g. the heavenly bodies have a circular movement), exhibit vividly this Fallacy of Simple Inspection.

2. _Whatever can be thought of apart, or has a separate name, exists apart as a separate entity_, e.g. Nature, Time, qualities, as e.g. Whiteness, and, worst of all, the Substantiæ Secundæ. Mysticism is this habit of ascribing objective existence to the subjective creations of the mind, and reasoning from them to the things themselves.

3. _A fact must follow a certain law, because we see no reason for its deviating from it in one way rather than in another._ This, which is the same as the Principle of the Sufficient Reason, has been used to prove the Law of Inertia (the very point to be proved, viz. that only external force can be a sufficient reason for motion _in a particular direction_, being assumed), and also the First Law of Motion, the argument being, in the latter case, that a moving body, if it do _not_ continue of itself to move uniformly in a straight line, must deviate right or left, and that there is _no reason_ for its going one way more than the other: to which the answer is, that, apart from experience, we could not know whether or not there were a reason. Geometers often fall into this Fallacy.

4. _The differences in nature must correspond to our received distinctions_ (in names and classifications). Thus, the Greeks thought that, by determining the meanings of words, they ascertained facts. Aristotle usually starts with 'We say thus or thus.' So, with the _Doctrine of Contrarieties_, in which the Pythagoreans and others assumed that oppositions in language imply similar ones in nature. Hence, too, the ancient belief in the essential difference between the laws of things terrestrial and things celestial, and in man's incapability of imitating nature's works. Bacon's error (which vitiates his inductive system) was analogous, in looking (either through his eagerness for practical results, or a lingering belief that causes were the sole object of philosophy) for the cause of given effects rather than the effects of a given cause. Hence sprang his tacit assumption (and that in enquiries into the causes of a thing's sensible qualities, where it was especially fatal), that in all cases, e.g. of heat or cold, the _forma_, or set of conditions, is _one_ thing. A similar notion, viz. that each property of gold, as of other things, has its one _forma_, produced the belief in Alchemy.

5. The conditions of a phenomenon often do resemble the phenomenon itself, e.g. in cases of Motion, Contagion, Feelings; but it is a Fallacy to suppose that _they must or probably will_. By this fancied law men guided their conjectures. Thus, the _Doctrine of Signatures_ was, that substances showed their uses as medicines by external resemblance, either to their supposed effect, or to the disease. So, the Cartesians, and even Leibnitz, argued, that nothing physical but previous motion could account for motion, explaining the human body's voluntary motions by Nervous Vibrations or by Animal Spirits. Hence, too, the inference that there is a correspondence between the physical qualities of the cause, and like or like-named ones, either of the phenomenon (e.g. between sharp particles and a sharp taste), or of its effects (e.g. between the redness of Mars, and fire and slaughter as results of that planet's influence). In metaphysics, the Epicureans' doctrine of _species sensibiles_, and the moderns' of _perception through ideas_, arose from this fallacy (combined with another, viz. that a thing cannot act where it is not). Again, the conditions of a thing are sometimes spoken of even as though they were the thing itself. Thus, in the Novum Organon, heat (i.e. really the conditions of the feeling of it) is called a kind of motion; and Darwin, in his Zoonomia, after describing _idea_ as a kind of _notion of external things_, defines it as _a motion of the fibres_. Cousin says: 'Tout ce qui est vrai de l'effet est vrai de la cause,' though, the reverse _might_ be true; and Coleridge affirms, as _an evident truth_, that mind and matter, as having no common property, cannot act on each other. The same fallacy led Leibnitz to his _pre-established harmony_, and Malebranche to his _occasional causes_. So, Cicero argues that mental pleasures, if arising from the bodily, could not, as they do, exceed their cause; and Descartes, that the Efficient Cause must have all the perfections of the effect. Conversely Descartes, too, and persons who assail, e.g. the Principle of Population by reference to Divine benevolence (thus implying that, because God is perfect, therefore what _they_ think perfection must obtain in nature), assume that effects must resemble their causes.