Gottfried Wilhelm Leibniz [1646-1716] wrote:
Meditations on Knowledge, Truth, and Ideas
Acta eruditorum, November, 1684
Since distinguished men are today engaged in controversies about true and false ideas, a matter of great importance for understanding the truth …, I should like briefly to explain what I think may be established about the different kinds and the criteria of ideas and of knowledge. Knowledge is either obscure or clear; clear knowledge is either confused or distinct; distinct knowledge is either inadequate or adequate, and also either symbolic or intuitive. The most perfect knowledge is that which is both adequate and intuitive. A concept is obscure which does not suffice for recognizing the thing represented, as when I merely remember some flower or animal which I have once seen but not well enough to recognize it when it is placed before me and to distinguish it from similar ones; or when I consider some term which [has been] defined poorly, or ‘cause’ as a common term for material, formal, efficient, and final cause, or other such terms of which we have no sure definition. A proposition also becomes obscure when it contains such a concept.
Knowledge is clear, therefore, when it makes it possible for me to recognize the thing represented. Clear knowledge, in turn, is either confused or distinct. It is confused when I cannot enumerate one by one the marks which are sufficient to distinguish the thing from others, even though the thing may in truth have such marks and constituents into which its concept can be resolved. Thus we know colors, odors, flavors, and other particular objects of the senses clearly enough and discern them from each other but only by the simple evidence of the senses and not by marks that can be expressed. So we cannot explain to a blind man what red is, nor can we explain such a quality to others except by bringing them into the presence of the thing and making them see, smell, or taste it, or at least by reminding them of some similar perception they have had in the past. Yet it is certain that the concepts of these qualities are composite and can be resolved, for they certainly have their causes. Likewise we sometimes see painters and other artists correctly judge what has been done well or done badly; yet they are often unable to give a reason for their judgment but tell the inquirer that the work which displeases them lacks “something, I know not what”.
A distinct concept, however, is the kind of notion which assayers have of gold; one, namely, which enables them to distinguish gold from all other bodies by sufficient marks and observations. We usually have such concepts about objects common to many senses, such as number, magnitude, and figure, and also about many affections of the mind such as hope and fear; in a word, about all concepts of which we have a nominal definition, which is nothing but the enumeration of sufficient marks. We may also have distinct knowledge of an indefinable concept, however, when this concept is primitive or is the mark of itself, that is, when it is irreducible and to be understood only through itself and therefore lacks requisite marks. But in composite concepts the single component marks are indeed sometimes known clearly but nevertheless confusedly, such as heaviness, color, aqua fortis, and others which are some of the marks of gold. Such knowledge of gold may therefore be distinct, but it is nonetheless inadequate.
But when every ingredient that enters into a distinct concept is itself known distinctly, or when analysis is carried through to the end, knowledge is adequate. I am not sure that a perfect example of this can be given by man, but our concept of numbers approaches it closely. Yet for the most part, especially in a longer analysis, we do not intuit the entire nature of the subject matter at once but make use of signs instead of things, though we usually omit the explanation of these signs in any actually present thought for the sake of brevity, knowing or believing that we have the power to do it. Thus when I think of a chiliogon, or a polygon of a thousand equal sides, I do not always consider the nature of a side and of equality and of a thousand (or the cube of ten), but I use these words, whose meaning appears obscurely and imperfectly to the mind, in place of the ideas which I have of them, because I remember that I know the meaning of the words but that their interpretation is not necessary for the present judgment. Such thinking I usually call blind or symbolic; we use it in algebra and in arithmetic, and indeed almost everywhere. When a concept is very complex, we certainly cannot think simultaneously of all the concepts which compose it. But when this is possible, or at least insofar as it is possible, I call the knowledge intuitive. There is no other knowledge than intuitive of a distinct primitive concept, while for the most part we have only symbolic thought of composites.
This already shows that we do not perceive the ideas even of those things which we know distinctly, except insofar as we use intuitive thought. It often happens that we falsely believe ourselves to have ideas of things in our mind, when we assume wrongly that we have already explained certain terms which we are using. It is not true, or at least it is ambiguous, to say, as some do, that we cannot speak of anything and understand what we say without having an idea of it. For often we understand after a fashion each single word or remember to have understood it earlier; yet because we are content with this blind thinking and do not sufficiently press the analysis of the concepts, we overlook a contradiction which the composite concept may involve. I was led to examine this point more distinctly by an argument which was famous among the Scholastics long ago and was revived by Descartes. It is an argument for the existence of God and is stated as follows. Whatever follows from the idea or definition of a thing can be predicated of the thing itself. Existence follows from the idea of God, or the most perfect being, or that than which no greater can be thought. For a most perfect being involves all perfections, among which existence is one. Therefore existence can be predicated of God.
It should be noticed however, that the most you can draw out of this argument is that if God is possible, it follows that he exists; for we cannot safely infer from definitions until we know that they are real or that they involve no contradiction. The reason for this is that from concepts which involve a contradiction, contradictory conclusions can be drawn simultaneously, and this is absurd.
[MGH: A modern social scientist would probably wish to use substitutes for the words ‘Gold’ and ‘God’. I choose (assayer of) ‘Society’ and (existence of) ‘System’.]
The Source:
Gottfried Wilhelm Leibniz, ‘Meditations on Knowledge, Truth, and Ideas’ [1684], in Gottfried Wilhelm Leibniz, Philosophical Papers and Letters, A Selection Translated and Edited, with an Introduction by Leroy E. Loemker, Kluwer Academic Publishers, 1989
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