The English philosophers, Bain and Mill, have combated this proposition with extraordinary ardour, like believers combating a heresy. But notwithstanding their attacks it remains intelligible, and the distinction between being and being perceived preserves its logical legitimacy. This may be represented, or may be thought; but can it be realised?
So far as regards external objects, I think we all, in fact, admit it. We all admit a distinction, between the existence of the outer world and the perception we have of it; its existence is one thing, and our perception of it is another. The existence of the world continues without interruption; our perception is continually interrupted by the most fortuitous causes, such as change of position, or even the blinking of the eyes; its existence is general, universal, independent of time and space; our perception is partial, particular, local, limited by the horizon of our senses, determined by the geographical position of our bodies, riddled by the distractions of our intelligence, deceived by the illusions of our minds, and above all diminished by the infirmity of our intelligence, which is able to comprehend so little of what it perceives. This is what we all admit in practice; the smallest of our acts implies the belief in something perceptible which is wider and more durable than our astonished perceptions. I could not write these lines unless I implicitly supposed that my inkstand, my paper, my pen, my room, and the surrounding world subsist when I do not see them. It is a postulate of practical life. It is also a postulate of science, which requires for its explanations of phenomena the supposition in them of an indwelling continuity. Natural science would become unintelligible if we were forced to suppose that with every eclipse of our perceptions material actions were suspended. There would be beginnings without sequences, and ends without beginnings.
Let us note also that acquired notions on the working of our nervous system allow us to give this postulate a most precise form: the external object is distinct from the nervous system and from the phenomena of perception which are produced when the nervous system is excited; it is therefore very easy to understand that this object continues to exist and to develop its properties, even when no brain vibrates in its neighbourhood.
Might we not, with the view of strengthening this conclusion as to the continuous existence of things, dispense with this postulate, which seems to have the character of a grace, of an alms granted to us? Might not this continuous existence of objects during the eclipses of our acts of consciousness, be demonstrated? It does not seem to me impossible. Let us suppose for a moment the correctness of the idealist thesis: all our legitimate knowledge of objects is contained within the narrow limits of actual sensation; then, we may ask, of what use is the reason? What is the use of the memory? These functions have precisely for their object the enlarging of the sphere of our sensations, which is limited in two principal ways, by time and by space. Thanks to the reason, we manage to see in some way that which our senses are unable to perceive, either because it is too distant from us, or because there are obstacles between us and the object, or because it is a past event or an event which has not yet taken place which is in question.
That the reason may be deceived is agreed. But will it be asserted that it is always deceived? Shall we go so far as to believe that this is an illegitimate mode of cognition? The idealist thesis, if consistent, cannot refuse to extend itself to this extreme conclusion; for a reasoned conclusion contains, when it has a meaning, a certain assertion on the order of nature, and this assertion is not a perception, since its precise object is to fill up the gaps in our perceptions. Not being a perception, it must be rejected, if one is an idealist.
The idealist will therefore keep strictly to the perception of the moment, and this is so small a thing when deprived of all the conjectures which enrich it, that the world, if reduced to this alone, would be but the skeleton of a world. There would then be no more science, no possibility of knowledge. But who could make up his mind thus to shut himself up in perception?
I suppose, indeed, that there will here be quibbling. This objection will be made: that in the hypothesis of a discontinuous existence of things, reason may continue to do its work, provided the intervention of a possible perception be supposed. Thus, I notice this morning, on going into my garden, that the pond which was dry yesterday is full of water. I conclude from this, "It has rained in the night." To be consistent with idealism, one must simply add: "If some one had been in the garden last night, he would have seen it rain." In this manner one must re-establish every time the rights of perception.
Be it so. But let us notice that this addition has no more importance than a prescribed formula in a notarial act; for instance, the presence of a second notary prescribed by the law, but always dispensed with in practice. This prescribed formula can always be imagined or even understood. We shall be in accord with idealism by the use of this easy little formula, "If some one had been there," or even by saying, "For a universal consciousness...." The difference of the realist and idealist theory becomes then purely verbal. This amounts to saying that it disappears. But there is always much verbalism in idealism.
One more objection: if this witness—the consciousness—suffices to give objects a continuity of existence, we may content ourselves with a less important witness. Why a man? The eyes of a mollusc would suffice, or those of infusoria, or even of a particle of protoplasm: living matter would become a condition of the existence of dead matter. This, we must acknowledge, is a singular condition, and this conclusion condemns the doctrine.