Can our senses deceive us?

Justification 4: Belief generally consists in nothing but the vivacity of an idea.

An idea may acquire this vivacity by its relation to some present impression. Impressions are naturally the most vivid perceptions of the mind. This quality is in part conveyed by the relation to every connected idea.

The relation: causes a smooth passage from the impression to the idea, and even gives a propensity to that passage.

The mind falls so easily from the one perception to the other.

The mind retains in the second perception a considerable share of the vivacity of the first perception.

It is excited by the lively impression.

This vivacity is conveyed to the related idea, without any great reduction in the passage, through the smooth transition and the propensity of the imagination.

Even if this propensity arises from some other principle, besides that of relation, it must still have the same effect and convey the vivacity from the impression to the idea.

This is exactly the present case.

Our memory presents us with so many instances of perceptions perfectly resembling each other that return at different times and after considerable interruptions.

These interruptions creates contradictions.

This resemblance gives us a propension to: consider these interrupted perceptions as the same, and connect them by a continued existence, in order to: justify this identity, and avoid those contradictions.

Here then we have a propensity to feign the continued existence of all sensible objects.

As this propensity arises from some lively impressions of the memory, it bestows a vivacity on that fiction.

In other words, it makes us believe the continued existence of body.

If we ascribe a continued existence to objects perfectly new to us, it is because the way they present themselves to our senses resembles the way of constant and coherent objects.

This resemblance is a source of reasoning and analogy.

It leads us to ascribe the same qualities to similar objects.

An intelligent reader will find it easier to assent to this system, than to comprehend it fully and distinctly.

After a little reflection, he will agree that every part carries its own proof along with it. Ordinary people suppose that their perceptions to be their only objects. At the same time, they believe the continued existence of matter. In that case: the origin of that belief lies in that continued existence, and any of our objects, or perceptions, are not identically the same after an interruption. Consequently, the opinion of their identity can never arise from reason, but from the imagination. The resemblance of certain perceptions seduces the imagination to think that those perceptions have an identity because those are only perceptions that we have a propension to think as the same. This propension to bestow an identity on our resembling perceptions, produces the fiction of a continued existence. That fiction and the identity are really false. This is acknowledged by all philosophers. Its only effect is to remedy the interruption of our perceptions. This interruption is the only circumstance contrary to their identity. Finally, this propension creates belief through the memory’s present impressions. Without the remembrance of former sensations, we would never have any belief of the continued existence of a body. Thus, we find that each of these parts is supported by the strongest proofs. All of them together form a consistent, perfectly convincing system. A strong propensity or inclination alone, without any present impression, will sometimes cause a belief or opinion. How much more when aided by that circumstance? The imagination has a natural propensity to ascribe a continued existence to sensible objects or perceptions which resemble each other in their interrupted appearance.

Yet a very little reflection and philosophy is enough to make us perceive the fallacy of that opinion. There is an intimate connection between: a continued existence, and a distinct or independent existence. The other follows as soon as we establish the first, as a necessary consequence. Wherever the mind follows its first and most natural tendency, a continued existence first takes place and draws the other along with it. But when we compare experiments and reason on them, we quickly perceive that the doctrine of the independent existence of our sensible perceptions is contrary to the plainest experience. This: leads us back to perceive our error in attributing a continued existence to our perceptions, and and is the origin of many very curious opinions, which we shall here endeavour to account for. We will first observe a few experiments which convince us that our perceptions do not have any independent existence.

When we press one eye with a finger, we immediately perceive all the objects to become double. Half of them are removed from their common and natural position. We clearly perceive that all our perceptions are dependent on our organs and the disposition of our nerves and animal spirits since: we do not attribute both these perceptions to continued existence, and these perceptions are both of the same nature. This opinion is confirmed by the seeming increase and reduction of objects according to their distance.

We learn that our sensible perceptions do not have any distinct or independent existence, from: the apparent alterations in their figure, the changes in their colour and other qualities from our sickness and distempers, and an infinite number of other experiments of the same kind. The natural consequence of this reasoning is that our perceptions have no more a continued than an independent existence (Hyphothesis A).

Philosophers have run into this opinion. They change their system. They distinguish, (as we shall do for the future) between perceptions and objects (Hyphothesis B): Perceptions are supposed to be interrupted, perishing, and different at every different return. Objects are supposed to be uninterrupted and preserve a continued existence and identity. But however philosophical this new system is, it is only a palliative remedy. It contains all the difficulties of the unphilosophical system, with some unique peculiarities. The mind does not lead us directly to embrace this opinion of the double existence of perceptions and objects. We can only arrive at it by passing through the common hypothesis of the identity and continuance of our interrupted perceptions. We would never think: that our perceptions and objects are different, and that our objects alone preserve a continued existence if: we were not persuaded: that our perceptions are our only objects, and that our perceptions continue to exist even when they no longer make their appearance to the senses. The philosophical Hypothesis B has no primary recommendation either to reason or the imagination. But it gets all its influence on the imagination from the natural Hypothesis A. This proposition contains two parts. Perceptions and Objects Have a Double Existence: External and Internal Part 1: The philosophical Hypothesis B has no primary recommendation to reason or the imagination.

The only existences that we are sure of are perceptions which: command our strongest assent, and are the first foundation of all our conclusions. The only conclusion that we can draw from the existence of one thing to the existence of another thing, is through cause and effect. It shows: that there is a connection between them, and that the existence of one is dependent on the existence of the other. Cause and effect is derived from past experience. It lets us find that two beings are: constantly conjoined together, and always present at once to the mind. Only perceptions are ever present to the mind. It follows that we may observe a conjunction or cause and effect between different perceptions. But we can never observe it between perceptions and objects. Therefore, it is impossible that we can ever create any conclusion on the existence of objects from the existence or qualities of perceptions. This philosophical Hypothesis B has no primary recommendation to the imagination

The imagination would never by itself have found such a principle. It will be difficult to prove this to the reader because it implies a negative, which in many cases will not admit of any positive proof. If anyone invents a system to account for the direct origin of this opinion from the imagination, we should be able to judge it. Let us assume that our perceptions are broken, interrupted, and still different from each other. Let any one show why the imagination directly and immediately proceeds to the belief of another existence which resemble these perceptions in their nature, but in a continued, uninterrupted, and identical form. I will renounce my present opinion if anyone can do this. The abstractedness and difficulty of thinking about broken perceptions makes this an improper subject for the fancy to work on. Whoever explains the origin of the common opinion on the continued and distinct existence of body, must: take the mind in its common situation, and suppose: that our perceptions are our only objects, and that our perceptions continue to exist even when they are not perceived. This opinion is false. But it is the most natural opinion. It alone has any primary recommendation to the imagination. Part 2: The philosophical Hypothesis B acquires all its influence on the imagination from the natural Hypothesis A.

This is a natural consequence of philosophical Hypothesis B having no primary recommendation to reason or the imagination. The philosophical Hypothesis B takes hold of many minds, particularly of those who reflect so little on this subject. It derives all its authority from the unphilosophical system since it has no original authority of its own. The philosophical Hypothesis B is connected to the natural Hypothesis A 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 appealing interruption is contrary to the identity. The interruption consequently does not extend beyond the appearance. The perception or object really continues to exist, even when absent from us. Our sensible perception, therefore, have a continued and uninterrupted existence. A little reflection destroys the conclusion that our perceptions have a continued existence, by showing that our perceptions have a dependent existence. This then rejects the opinion that there is any continued existence in nature that is preserved even when it no longer appears to the senses. The philosophical Hypothesis B, however, is different. The rejection of the independence and continuance of our sensible perceptions leads to the rejection of the opinion of a continued existence. All sects agree in the latter sentiment. a few extravagant skeptics agree in the They have kept that opinion in words only. They were never able to bring themselves to believe it. There is a great difference between opinions that come from a calm and profound reflection, and opinions that come from our instinct or natural impulse.

This difference is due to their suitableness and conformity to the mind. If these opinions become contrary, it is easy to foresee which of them will have the advantage. As long as our attention is on philosophy, the philosophical and studied principle may prevail. But the moment we relax our thoughts, nature will: display herself, and draw us back to our natural opinion. Nature has sometimes such an influence, that she can stop our progress, even during our most profound reflections.

She can keep us from running with all the consequences of any philosophical opinion. We clearly perceive the dependence and interruption of our perceptions. But we stop short. We never reject the notion of an independent and continued existence. That opinion has taken such deep root in the imagination. It is impossible to ever eradicate it. No metaphysical conviction on the dependence of our perceptions can eradicate it. Our natural and obvious principles here prevail above our studied reflections. But there is some struggle and opposition so long as these rejections retain any force or vivacity. To set ourselves at ease in this, we contrive a new Hypothesis C.

This hypothesis comprehends these principles of reason and imagination. This is the philosophical hypothesis of the double existence of perceptions and objects. It pleases our reason by allowing our dependent perceptions to be interrupted and different. It pleases the imagination by ascribing a continued existence to something else, which we call ‘objects’. Therefore, this philosophical Hypothesis C is the monstrous offspring of two principles which are: contrary to each other, both at once embraced by the mind, and unable to mutually 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. We elude the contradiction between these opinions by a new fiction.

This fiction is conformable to the hypotheses of reflection and fancy. It ascribes these contrary qualities to different existences: the interruption to perceptions, and the continuance to objects. Nature is obstinate.

It will not quit the field no matter how strongly attacked by reason. Reason is so clear in the point. It is impossible to disguise her. Unable to reconcile these two enemies, we try to set ourselves at ease by successively: granting whatever each demands, and feigning a double existence, where each may find something that has all the conditions that it wants. We would never run into this opinion of a double existence if we were fully convinced that our resembling perceptions are continued, identical, and independent, since we would: find satisfaction in our first supposition, and not look beyond it. If we were fully convinced that our perceptions are dependent, interrupted, and different, we would be as little inclined to embrace the opinion of a double existence.

Since in that case, we would: clearly perceive the error of our first supposition of a continued existence, and never regard it any further. Therefore, this opinion arises from:

the mind’s intermediate situation, and such an adherence to these two contrary principles. This adherence makes us seek some pretext to justify our receiving both. Happily, this is finally found in the system of a double existence. Another advantage of this philosophical Hypothesis C is its similarity to the natural Hypothesis A.

It lets us humour our reason for a moment, when it becomes troublesome. Yet it allows us to easily return to our natural notions upon its smallest negligence. Accordingly, we find that philosophers do not neglect this advantage.

They have exploded opinions that our perceptions: are our only objects, and continue identically and uninterruptedly the same in all their interrupted appearances. After leaving their closets, those philosophers immediately mingle with mankind with those opinions. This system has other particulars which depend on the fancy in a very conspicuous way.

Two of these are: We suppose external objects to resemble internal perceptions. 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. Even if they could afford such a conclusion, we would never have any reason to infer that our objects resemble our perceptions. Therefore, that opinion is derived only from the imagination borrowing its ideas from some precedent perception. We can only conceive perceptions. Therefore, we must make everything resemble them. We suppose our objects in general to resemble our perceptions. We take it for granted, that every particular object resembles that perception, which it causes. Cause and effect determines us to join resemblance. The ideas of these existences are already united together in the fancy by cause and effect. We naturally add resemblance to complete the union. We have a strong propensity to complete every union by joining new relations to those which we have previously observed between any ideas. We shall observe this in Section 5. I begun this subject with premising, that we should have an implicit faith in our senses.

This is the conclusion from my whole reasoning. But to be honest, I feel the opposite. I am more inclined to put no faith at all in my senses or imagination, than to have confidence on them. I cannot conceive how such trivial qualities of the fancy, conducted by such false suppositions, can ever lead to any solid and rational system. The coherence and constancy of our perceptions produce the opinion of their continued existence, even if these qualities of perceptions have no perceivable connection with such an existence. The constancy of our perceptions has the most considerable effect.

Yet it is attended with the greatest difficulties. It is a gross illusion to suppose, that our resembling perceptions are numerically the same. This illusion leads us to think that these perceptions are uninterrupted and still exist even when they are not present to the senses. This is the case with our popular system. Our philosophical system is liable to the same difficulties. It is loaded with this absurdity, to the point that it immediately denies the absurdity and then establishes the unphilosophical system. Philosophers deny our resembling perceptions to be identically the same and uninterrupted.

Yet philosophers believe them to the point that they arbitrarily invent a new set of perceptions, to which they attribute these qualities. For we may well suppose in general, but it is 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? How can we justify to ourselves any belief we repose in them? This skeptical doubt of reason and the senses is a malady which can never be radically cured.

It must return on us every moment, however we chase it away. We may sometimes seem free from it. It is impossible on any system to defend our understanding or senses.

We merely expose them further when we try to justify them in that way. The skeptical doubt arises naturally from a profound and intense reflection on those subjects. It always increases the further we carry our reflections, whether in opposition or conformity. Carelessness and inattention alone can afford us any remedy. That is why I rely entirely on them. Whatever the reader’s opinion is now, he will be persuaded after an hour, that there is both an external and internal world. I will examine some general ancient and modern systems which have been proposed of both, before I proceed to a more particular inquiry on our impressions.