When using any part of this text - by Witold Marciszewski - refer, please, to the above original URL.
Mathesis Universalis No.4, Autumn 1997 http://www.pip.com.pl/MathUniversalis/4/
Empirical Clearness according to Peirce
In his paper How to Make Our Ideas Clear
This famous paper by Charles S. Peirce so entitled appeared in Popular Science Monthly 12 (January 1878), 286-302. It states the foundations for his epistemology in which the central role is played by the notion of clearness and that of belief. Though Peirce himself does not coordinate these concepts with each other in an explicit way, they may be combined in the concept of apprehension, the third he uses frequently in the context "clearness of apprehension". To wit, when a thing is apprehended clearly as being so-and-so, this fact legitimizes the belief that it actually is so-and-so.
THIS IS HOW Peirce himself declares the goal of logic.
The very first lesson that we have a right to demand that logic shall teach us is, how to make our ideas clear. [...] To know what we think, to be masters of our own meaning, will make a solid foundation for great and weighty thought.When so appreciating this "first lesson" he launched a strong attack against the way of explaining what clearness of apprehension consists in as he found it in contemporary treatises on logic. When seeking for those guilty of the obsurity of the term "clearness", he hinted at Descartes and Leibniz. He did not offer, though, a textual analysis of either of these philosophers to show a connection between their teachings and what he met in 19th century treatises on logic; moreover, he misinterpreted either of them, what in the case of Leibniz can be explained by the fact that most important Leibniz's writings were not accessible in Peirce's times yet (hence historical parts of his discussion will be disregarded).This is how Peirce reports on the definition of clearness as found by him in the treatises he was acquainted with.
A clear idea is defined as one which is so apprehended that it will be recognized wherever it is met with, and so that no other will be mistaken for it. If it fails of this clearness, it is said to be obscure.Peirce criticizes this definition that it reduces clearness to a subjective feeling of familiarity.Merely - he says - to have such an acquaintance with the idea as to have become familiar with it, and to have lost all hesitancy in recognizing it in ordinary cases, hardly seems to deserve the name of clearness of apprehension, since after all it only amounts to a subjective feeling of mastery which may be entirely mistaken. I take it, however, that when the logicians speak of clearness, they mean nothing more than such a familiarity with an idea, since they regard the quality as but a small merit, which needs to be supplemented by another, which they call distinctness.As to the postulate of distinctness as Peirce finds it in standard textbooks of his time, he explains it as the demand of defining an idea, the definition being given - as he puts it - "in abstract terms".
Peirce is ready to concede that to make a notion fully familiar, and then to define it, may be two successive steps toward clearness of apprehension. But - he objects - these steps do not grant any higher perspicuity of thought, Therefore he suggests how to make the third step, the one which proves decisive. Here is his statement (italics mine - WM).
The rule for attaining the third grade of clearness of apprehension is as follows: Consider what effects, that might conceivably have practical bearings, we conceive the object of our conception to have. Then, our conception of these effects is the whole of our conception of the object.PRACTICAL BEARINGS are meant to oppose to abstract terms mentioned by Peirce in his account of the standard notion of distinctness (see above). To explain how such bearing should be understood, Peirce offers a handful of examples. The nicest and most sophisticated is concerned with the physical concept of force as defined with recourse to practical bearings. However, let us take advantage of the simplest one, concerned with the term "hard". Let us ask what we mean by calling a thing hard.Evidently that it will not be scratched by many other substances. The whole conception of this quality, as of every other, lies in its conceived effects. There is absolutely no difference between a hard thing and a soft thing so long as they are not brought to the test. Suppose, then, that a diamond could be crystallized in the midst of a cushion of soft cotton, and should remain there until it was finally burned up. Would it be false to say that that diamond was soft? This seems a foolish question, and would be so, in fact, except in the realm of logic. There such questions are often of the greatest utility as serving to bring logical principles into sharper relief than real discussions ever could. In studying logic we must not put them aside with hasty answers, but must consider them with attentive care, in order to make out the principles involved. We may, in the present case, modify our question, and ask what prevents us from saying that all hard bodies remain perfectly soft until they are touched, when their hardness increases with the pressure until they are scratched. Reflection will show that the reply is this: there would be no falsity in such modes of speech. They would involve a modification of our present usage of speech with regard to the words hard and soft, but not of their meanings. For they represent no fact to be different from what it is; only they involve arrangements of facts which would be exceedingly maladroit. This leads us to remark that the question of what would occur under circumstances which do not actually arise is not a question of fact, but only of the most perspicuous arrangement of them.In this text, one recognizes a possible source of the theory of operational definitions as once developed by the physicist P.W.Bridgman in his numerous contributions, eg, in "Operational Analysis" (Philosophy of Science 5, 1938, 114-131). Those definitions resemble R.Carnap's reduction sentences (see his Testability and Meaning, 1936/37) meant to reduce theoretical predicates to observational ones. Thus there is an extensive context of modern literature to interpret Peirce's notion of clarity.The same context helps us to understand a relation of so conceived clarity of concepts to reasonabless of beliefs. If some philosophical beliefs were blamed by Carnap and his followers as lacking cognitive value, hence irrational, this was motivated by the lack of any logical connection between the concepts involved and observational predicates.
PEIRCE'S APPROACH TO CLARITY is possibly the one best suited to produce intelligent artificial believers. For in defining clarity one internal states, in particular, states of consciousness are to be disregarded. Even if artifical consciousness is not unthinkable in a long run, the first steps toward intelligent beliefs of machines should be guided by Peirce's ideas. These make it possible to create a common language of robots and human beings, provided that Peirce is right when stating the following.
What a thing means is simply what habits it involves. Now, the identity of a habit depends on how it might lead us to act, not merely under such circumstances as are likely to arise, but under such as might possibly occur, no matter how improbable they may be. What the habit is depends on when and how it causes us to act. As for the when, every stimulus to action is derived from perception; as for the how, every purpose of action is to produce some sensible result. Thus, we come down to what is tangible and conceivably practical, as the root of every real distinction of thought, no matter how subtile it may be; and there is no distinction of meaning so fine as to consist in anything but a possible difference of practice.Obviously, intelligent beliefs, as entirely definable by intelligent habits and behaviour, can be common to people and machines. Hence, the challenge to be met by AI - that of creating intelligent artificial beliefs - should be met at the field determined by Peirce.
