The five principal causes of Error

We have just seen that one falls into error only because one does not make the use one ought to make of one’s freedom: that it is for lack of moderating the eagerness and ardor of the will for mere appearances of truth that one is mistaken, and that error consists only in a consent of the will that has more extent than the perception of the understanding, since one would not be mistaken if one judged only of what one sees.

But, although properly speaking there is only the misuse of freedom that is the cause of error, one can nevertheless say that we have many faculties that are causes of our errors — not true causes, but causes that can be called occasional. All our ways of perceiving are so many occasions for us to be mistaken. For since our false judgments contain two things — the consent of the will, and the perception of the understanding — it is quite clear that all our ways of perceiving can give us some occasion to be mistaken, since they can lead us to precipitate consents.

Now, because it is necessary first to make the mind feel its weaknesses and its wanderings, so that it may enter into just desires to be delivered from them, and that it may rid itself more easily of its prejudices, we shall try to make an exact division of its ways of perceiving, which will be like so many headings, to each of which we shall subsequently refer the different errors to which we are subject.

The soul can perceive things in three ways: through the pure understanding, through the imagination, through the senses.

It perceives through the pure understanding spiritual things, universals, common notions, the idea of perfection, that of an infinitely perfect being, and generally all its thoughts when it knows them by the reflection it makes upon itself. It even perceives material things through the pure understanding — extension with its properties; for only the pure understanding can perceive a perfect circle and square, a figure of a thousand sides, and similar things. These sorts of perceptions are called pure intellections, or pure perceptions, because it is not necessary for the mind to form bodily images in the brain to represent all these things to itself.

Through the imagination, the soul perceives only material beings, when, being absent, it renders them present to itself by forming images of them in the brain. It is in this way that one imagines all sorts of figures — a circle, a triangle, a face, a horse, cities and countryside — whether one has already seen them or not. These sorts of perceptions can be called imaginations, because the soul represents these objects to itself by forming images of them in the brain; and because one cannot form images of spiritual things, it follows that the soul cannot imagine them; which should be well noted.

Finally, the soul perceives through the senses only sensible and gross objects, when, being present, they make an impression on the external organs of its body and this impression is communicated to the brain, or when, being absent, the course of animal spirits makes a similar impression in the brain. It is thus that it sees plains and rocks present to its eyes, that it knows the hardness of iron, and the point of a sword, and similar things; and these sorts of sensations are called feelings or sensations.

The soul therefore perceives nothing except in these three ways; which is easy to see if one considers that the things we perceive are either spiritual or material. If they are spiritual, only the pure understanding can know them; if they are material, they will be present or absent. If they are absent, the soul ordinarily represents them to itself only through the imagination; but if they are present, the soul can perceive them through the impressions they make on its senses; and thus our souls perceive things only in three ways: through the pure understanding, through the imagination, and through the senses.

One can therefore regard these three faculties as certain headings to which one can refer the errors of men and the causes of these errors, and thus avoid the confusion into which their great number would infallibly throw us if we wished to speak of them without order.

But our inclinations and our passions also act very strongly upon us; they dazzle our minds with false lights, and they cover and fill them with darkness. Thus our inclinations and our passions engage us in an infinite number of errors when we follow this false light and this deceptive illumination they produce in us. One must therefore consider them along with the three faculties of the mind, as sources of our wanderings and our faults, and join to the errors of the senses, of the imagination, and of the pure understanding those that can be attributed to the passions and natural inclinations. Thus one can refer all the errors of men and their causes to five headings, and they will be treated according to this order.

General design of the entire work, and the design of book 1

First, we shall speak of the errors of the senses; second, of the errors of the imagination; third, of the errors of the pure understanding; fourth, of the errors of the inclinations; fifth, of the errors of the passions; finally, after having tried to deliver the mind from the errors to which it is subject, we shall give a general method for conducting oneself in the search for truth.

I shall explain the errors of our senses, or rather the errors into which we fall by not making the use we ought to make of our senses, and we shall not dwell so much on particular errors, which are almost infinite, as on the general causes of these errors and on the things that are believed necessary for the knowledge of the nature of the human mind.