Philosophical Works, v. 1 · David Hume
OF SCEPTICISM WITH REGARD TO THE SENSES.
The natural consequence of this reasoning should be, that our perceptions have no more a continued than an independent existence; and, indeed, philosophers have so far run into this opinion, that they change their system, and distinguish (as we shall do for the future) betwixt perceptions and objects, of which the former are supposed to be interrupted and perishing, and different at every different return; the latter to be uninterrupted, and to preserve a continued existence and identity. But however philosophical this new system may be esteemed, I assert that 'tis only a palliative remedy, and that it contains all the difficulties of the vulgar system, with some others that are peculiar to itself. There are no principles either of the understanding or fancy, which lead us directly to embrace this opinion of the double existence of perceptions and objects, nor can we arrive at it but by passing through the common hypothesis of the identity and continuance of our interrupted perceptions. Were we not first persuaded that our perceptions are our only objects, and continue to exist even when they no longer make their appearance to the senses, we should never be led to think that our perceptions and objects are different, and that our objects alone preserve a continued existence. "The latter hypothesis has no primary recommendation either to reason or the imagination, but acquires all its influence on the imagination from the former." This proposition contains two parts, which we shall endeavour to prove as distinctly and clearly as such abstruse subjects will permit.
As to the first part of the proposition, _that this philosophical hypothesis has no primary recommendation, either to reason or the imagination_, we may soon satisfy ourselves with regard to _reason_, by the following reflections. The only existences, of which we are certain, are perceptions, which, being immediately present to us by consciousness, command our strongest assent, and are the first foundation of all our conclusions. The only conclusion we can draw from the existence of one thing to that of another, is by means of the relation of cause and effect, which shows, that there is a connexion betwixt them, and that the existence of one is dependent on that of the other. The idea of this relation is derived from past experience, by which we find, that two beings are constantly conjoined together, and are always present at once to the mind. But as no beings are ever present to the mind but perceptions, it follows, that we may observe a conjunction or a relation of cause and effect between different perceptions, but can never observe it between perceptions and objects. 'Tis impossible, therefore, that from the existence or any of the qualities of the former, we can ever form any conclusion concerning the existence of the latter, or ever satisfy our reason in this particular.
'Tis no less certain, that this philosophical system has no primary recommendation to the _imagination_, and that that faculty would never, of itself, and by its original tendency, have fallen upon such a principle. I confess it will be somewhat difficult to prove this to the full satisfaction of the reader; because it implies a negative, which in many cases will not admit of any positive proof. If any one would take the pains to examine this question, and would invent a system, to account for the direct origin of this opinion from the imagination, we should be able, by the examination of that system, to pronounce a certain judgment in the present subject. Let it be taken for granted, that our perceptions are broken and interrupted, and, however like, are still different from each other; and let any one, upon this supposition, show why the fancy, directly and immediately, proceeds to the belief of another existence, resembling these perceptions in their nature, but yet continued, and uninterrupted, and identical; and after he has done this to my satisfaction, I promise to renounce my present opinion. Meanwhile I cannot forbear concluding, from the very abstractedness and difficulty of the first supposition, that 'tis an improper subject for the fancy to work upon. Whoever would explain the origin of the _common_ opinion concerning the continued and distinct existence of body, must take the mind in its _common_ situation, and must proceed upon the supposition, that our perceptions are our only objects, and continue to exist even when they are not perceived. Though this opinion be false, 'tis the most natural of any, and has alone any primary recommendation to the fancy.
As to the second part of the proposition, _that the philosophical system acquires all its influence on the imagination from the vulgar one_; we may observe, that this is a natural and unavoidable consequence of the foregoing conclusion, _that it has no primary recommendation to reason or the imagination_. For as the philosophical system is found by experience to take hold of many minds, and, in particular, of all those who reflect ever so little on this subject, it must derive all its authority from the vulgar system, since it has no original authority of its own. The manner in which these two systems, though directly contrary, are connected together, may be explained as follows. The imagination naturally runs on in this train of thinking. Our perceptions are our only objects: resembling perceptions are the same, however broken or uninterrupted in their appearance: this appearing interruption is contrary to the identity: the interruption consequently extends not beyond the appearance, and the perception or object really continues to exist, even when absent from us: our sensible perceptions have, therefore, a continued and uninterrupted existence. But as a little reflection destroys this conclusion, that our perceptions have a continued existence, by showing that they have a dependent one, 'twould naturally be expected, that we must altogether reject the opinion, that there is such a thing in nature as a continued existence, which is preserved even when it no longer appears to the senses. The case, however, is otherwise. Philosophers are so far from rejecting the opinion of a continued existence upon rejecting that of the independence and continuance of our sensible perceptions, that though all sects agree in the latter sentiment, the former, which is in a manner its necessary consequence, has been peculiar to a few extravagant sceptics; who, after all, maintained that opinion in words only, and were never able to bring themselves sincerely to believe it.
There is a great difference betwixt such opinions as we form after a calm and profound reflection, and such as we embrace by a kind of instinct or natural impulse, on account of their suitableness and conformity to the mind. If these opinions become contrary, 'tis not difficult to foresee which of them will have the advantage. As long as our attention is bent upon the subject, the philosophical and studied principle may prevail; but the moment we relax our thoughts, nature will display herself, and draw us back to our former opinion. Nay she has sometimes such an influence, that she can stop our progress, even in the midst of our most profound reflections, and keep us from running on with all the consequences of any philosophical opinion. Thus, though we clearly perceive the dependence and interruption of our perceptions, we stop short in our career, and never upon that account reject the notion of an independent and continued existence. That opinion has taken such deep root in the imagination, that 'tis impossible ever to eradicate it, nor will any strained metaphysical conviction of the dependence of our perceptions be sufficient for that purpose.
But though our natural and obvious principles here prevail above our studied reflections, 'tis certain there must be some struggle and opposition in the case; at least so long as these reflections retain any force or vivacity. In order to set ourselves at ease in this particular, we contrive a new hypothesis, which seems to comprehend both these principles of reason and imagination. This hypothesis is the philosophical one of the double existence of perceptions and objects; which pleases our reason, in allowing that our dependent perceptions are interrupted and different, and at the same time is agreeable to the imagination, in attributing a continued existence to something else, which we call _objects_. This philosophical system, therefore, is the monstrous offspring of two principles, which are contrary to each other, which are both at once embraced by the mind, and which are unable mutually to destroy each other. The imagination tells us, that our resembling perceptions have a continued and uninterrupted existence, and are not annihilated by their absence. Reflection tells us, that even our resembling perceptions are interrupted in their existence, and different from each other.
The contradiction betwixt these opinions we elude by a new fiction, which is conformable to the hypotheses both of reflection and fancy, by ascribing these contrary qualities to different existences; the _interruption_ to perceptions, and the _continuance_ to objects. Nature is obstinate, and will not quit the field, however strongly attacked by reason; and at the same time reason is so clear in the point, that there is no possibility of disguising her. Not being able to reconcile these two enemies, we endeavour to set ourselves at ease as much as possible, by successively granting to each whatever it demands, and by feigning a double existence, where each may find something that has all the conditions it desires. Were we fully convinced that our resembling perceptions are continued, and identical, and independent, we should never run into this opinion of a double existence; since we should find satisfaction in our first supposition, and would not look beyond. Again, were we fully convinced that our perceptions are dependent, and interrupted, and different, we should be as little inclined to embrace the opinion of a double existence; since in that case we should clearly perceive the error of our first supposition of a continued existence, and would never regard it any farther. 'Tis therefore from the intermediate situation of the mind that this opinion arises, and from such an adherence to these two contrary principles, as makes us seek some pretext to justify our receiving both; which happily at last is found in the system of a double existence.
Another advantage of this philosophical system is its similarity to the vulgar one, by which means we can humour our reason for a moment, when it becomes troublesome and solicitous; and yet upon its least negligence or inattention, can easily return to our vulgar and natural notions. Accordingly we find, that philosophers neglect not this advantage, but, immediately upon leaving their closets, mingle with the rest of mankind in those exploded opinions, that our perceptions are our only objects, and continue identically and uninterruptedly the same in all their interrupted appearances. There are other particulars of this system, wherein we may remark its dependence on the fancy, in a very conspicuous manner. Of these, I shall observe the two following. _First_, we suppose external objects to resemble internal perceptions. I have already shown, that the relation of cause and effect can never afford us any just conclusion from the existence or qualities of our perceptions to the existence of external continued objects: and I shall farther add, that even though they could afford such a conclusion, we should never have any reason to infer that our objects resemble our perceptions. That opinion, therefore, is derived from nothing but the quality of the fancy above explained, _that it borrows all its ideas from some precedent perception_. We never can conceive any thing but perceptions, and therefore must make every thing resemble them.
Secondly, as we suppose our objects in general to resemble our perceptions, so we take it for granted, that every particular object resembles that perception which it causes. The relation of cause and effect determines us to join the other of resemblance; and the ideas of these existences being already united together in the fancy by the former relation, we naturally add the latter to complete the union. We have a strong propensity to complete every union by joining new relations to those which we have before observed betwixt any ideas, as we shall have occasion to observe presently.[8] Having thus given an account of all the systems, both popular and philosophical, with regard to external existences, I cannot forbear giving vent to a certain sentiment which arises upon reviewing those systems. I begun this subject with premising, that we ought to have an implicit faith in our senses, and that this would be the conclusion I should draw from the whole of my reasoning. But to be ingenuous, I feel myself _at present_ of a quite contrary sentiment, and am more inclined to repose no faith at all in my senses, or rather imagination, than to place in it such an implicit confidence. I cannot conceive how such trivial qualities of the fancy, conducted by such false suppositions, can ever lead to any solid and rational system. They are the coherence and constancy of our perceptions, which produce the opinion of their continued existence; though these qualities of perceptions have no perceivable connexion with such an existence. The constancy of our perceptions has the most considerable effect, and yet is attended with the greatest difficulties. 'Tis a gross illusion to suppose, that our resembling perceptions are numerically the same; and 'tis this illusion which leads us into the opinion, that these perceptions are uninterrupted, and are still existent, even when they are not present to the senses.
This is the case with our popular system. And as to our philosophical one, 'tis liable to the same difficulties; and is, over and above, loaded with this absurdity, that it at once denies and establishes the vulgar supposition. Philosophers deny our resembling perceptions to be identically the same, and uninterrupted; and yet have so great a propensity to believe them such, that they arbitrarily invent a new set of perceptions, to which they attribute these qualities. I say, a new set of perceptions: for we may well suppose in general, but 'tis impossible for us distinctly to conceive, objects to be in their nature any thing but exactly the same with perceptions. What then can we look for from this confusion of groundless and extraordinary opinions but error and falsehood? And how can we justify to ourselves any belief we repose in them?
This sceptical doubt, both with respect to reason and the senses, is a malady which can never be radically cured, but must return upon us every moment, however we may chase it away, and sometimes may seem entirely free from it. 'Tis impossible, upon any system, to defend either our understanding or senses; and we but expose them farther when we endeavour to justify them in that manner. As the sceptical doubt arises naturally from a profound and intense reflection on those subjects, it always increases the farther we carry our reflections, whether in opposition or conformity to it. Carelessness and inattention alone can afford us any remedy. For this reason I rely entirely upon them; and take it for granted, whatever may be the reader's opinion at this present moment, that an hour hence he will be persuaded there is both an external and internal world; and, going upon that supposition, I intend to examine some general systems, both ancient and modern, which have been proposed of both, before I proceed to a more particular inquiry concerning our impressions. This will not, perhaps, in the end, be found foreign to our present purpose. [1] Part II. Sect. 6. [2] Sect. 5. [3] Part II. Sect. 4. [4] Part II. Sect. 5. [5] Part. II. Sect. 5.
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