analysis of judgment, to render still more precise the idea of that intellectual operation, and of its results, and to repeat several of the effects already recognized in the signs, and several of their relations, with the nature of the ideas which they represent.
At the commencement of the volume which treats more especially of logic, I of necessity looked back on the ancient history of science, to show, that true logic is absolutely the same science with that of the formation, the expression, and combination of our ideas; that is to say, that which has been since called Ideology, general grammar, or analysis of the understanding; and to show that my two first volumes are but the restoration, more or less fortunate, of the two first parts of the ancient logics, and the supplement of that which has always been wanting to these very important preliminaries. I have moreover been under the necessity of insisting also on the explication of the idea of existence, and on that of the reality of our preceptions, and of their necessary concordance with the reality of the beings which cause them, when they are all legitimately deduced from the first and direct impressions, which these beings make on us.
At present I find myself, in like manner, constrained to speak again of the conclusions of this logic, before advancing further, and not to apply my theory of the causes of certitude and error, to the study of the will and its effects, without having given it some new developements. The reader ought to pardon these frequent retrospects; for they arise almost necessarily from the nature of the subject, from the manner in which it has been treated hitherto, and from the necessity we are under, of anticipating a crowd of objections, when we wish to render a new opinion acceptable.
Let me be permitted then to mention here again, that I have reduced the whole science of logic to the observation of two facts, which result manifestly from the scrupulous examination of our intellectual operations. The first is, that our perceptions being every thing for us, we are perfectly, completely, and necessarily sure of all that we actually feel. The second, which is but a consequence of that, is that none of our judgments, taken separately, can be erroneous, since, for the very reason that we see one idea in another, it must be actually there; but that their falsity, when it takes place, is purely relative to all the anterior judgments, which we permit to subsist, and consists in this, that we believe the idea, in which we see a new element, to be the same we have always had under the same sign, while it is really different, since the new element we actually see there is incompatible with some of those which we have previously seen there. So that, to avoid contradiction, it would be necessary either to take away the former, or not to admit the latter.
After having established these two principles, or rather these two facts, I have given some elucidations, I have met in advance some objections, I have shown that these two objections are equally true, whatever be the nature of our ideas, and whatever the use we make of them; and hence I have concluded, that all the rules whatsoever which have been prescribed for the form of our reasonings, to assure us of their justice, are absolutely useless and illusory; and that our sole and only means of preserving ourselves from error, is to assure ourselves well that we comprehend the idea of which we judge, and if it be doubtful, to make the most complete enumeration possible of the elements which compose it, and principally of those which may either implicitly contain or exclude that whose admission or exclusion is in question.
It is here that, without more details, I have terminated my treatise on logic, which consequently finishes almost at the point at which all the others commence. This ought so to be, as I meant to speak only of the science; while other logicians, neglecting the science almost entirely, have occupied themselves only with the art. I confess my belief, that my labour is more useful than theirs; because, in every matter, it is always very difficult, from premature consequences, to remount to the principles which ought to have served as their foundation. Whereas, when we have well established the first truths, it is easy to deduce the consequences which flow from them. Yet this second operation is important also, and as a subject is not completely treated of, but when it is executed, I will present, before proceeding further, summarily, but methodically, the series of practical maxims, which result from my method of considering our means of knowledge. The use I shall afterwards make of these same means, in the study of the will and its effects, will be an example of the manner in which these rules are applied in all our researches.
Aphorism First.*
We know our existence only by the impressions we experience, and that of beings other than ourselves, but by the impressions which they cause on us.
OBSERVATION.
In like manner, as all our propositions may be reduced to the form of enunciative propositions, because at bottom they all express a judgment, so all our enunciative propositions may afterwards be always reduced to some one of these: I think, I feel, or I perceive, that such a thing is in such a manner, or that such a being produces such an effect; propositions of which we are ourselves the subject, because in fact we are always the subject of all our judgments, since they never express but the impression which we experience.
COROLLARY.
From hence it follows: 1st. That our perceptions are all of them always such as we feel them, and are not susceptible of any error, taken each separately, and in itself.
2dly. That if in the different combinations, we make of them, we add to them nothing which is not primitively comprised in them, implicitly or explicitly, they are always conformable to the existence of the beings which cause them, since that existence is not known to us but by them, and consists for us only in those perceptions.
3dly. That we know nothing but relatively to ourselves, and to our means of receiving perceptions.
4thly. That these perceptions are every thing for us; that we know nothing ever but our perceptions; that they are the only things truly real for us, and that the reality which we recognize in the beings that cause them is only secondary, and consists only in the permanent power of always causing the same impressions under the same circumstances, whether on ourselves, or on other sensible beings, who give us an account of them (also by the impressions which they cause in us) when we have become able to hold communication with them by signs.
Aphorism Second.
Since our perceptions are all of them always such as we feel them, when we perceive one idea in another, it is actually and really there, from the very circumstance of our perceiving it there: hence no one of our judgments taken separately and detached, is false. It has always and necessarily the certitude which belongs inevitably to each of our actual perceptions.
COROLLARY.
None of our judgments then can be false, but relatively to anterior judgments, and that suffices to render them false relatively to the existence of beings, the causes of our impressions, if these anterior judgments were just, relatively to that existence.
Aphorism Third.
When we see in an idea, or a perception, an element incompatible with those which it included before, this idea is different from what it was, for, such as it was, it excluded this new element which we see there; and, such as it is, it excludes those which are incompatible with it.
COROLLARY.
That it may then be the same idea which it was before, we must exclude from it the element which we see there at present, or if those which are repugnant to it, are misplaced in this idea, they must themselves be excluded from it; that is to say, it must be rendered such as it was, when they were erroneously admitted
