皮尔士在《通俗科学月刊》（Popular Science Monthly）上发表的《信念的确定》（The Fixation of Belief，1877）与《如何使我们的观念清晰》（How to Make Our Ideas Clear，1878)，被认为是实用主义的代表作。

（注：这是重新翻译的文本）

《如何使我们的观念清晰》 - 皮尔士

第一章

凡是看过普通的现代逻辑学文章的人，无疑会记得区分清晰与模糊，明确与混淆的概念。这样的区分在书中已经存在了近两个世纪，没有任何改进和变化，一般被逻辑学家认为是他们学说中的瑰宝。

一个清晰的概念被定义为：无论在哪里遇到它，都会被识别出来，而没有其他东西被误认为是它。如果一个概念缺乏这种清晰性，就被说成是模糊的。 

这是一个相当简洁的哲学术语，然而，由于他们所定义的是清晰性，我希望逻辑学家们能把他们的定义说得更清楚一些。在任何情况下都不把一个概念误认为另一个概念，不管它是以多么复杂的形式出现的，这确实意味着智力的巨大力量和清晰性，在这个世界上是很少见的。另一方面，仅仅是对一个概念熟悉，熟悉到在一般情况下能毫不犹豫地认出它，似乎不值得称为清晰的理解力，因为这毕竟只是一种主观的掌握感，可能是完全错误的。然而，我认为，逻辑学家所说的“清晰”不过是指对一个概念的这种熟悉，因为他们并不看重这种质量本身，以至于需要由另一种质量来补充，他们称之为明确性。

一个明确的概念被定义为不包含任何不清晰的内容，这是技术性语言。逻辑学家对一个概念的内容的理解是它的定义中所包含的东西。因此，按照他们的说法，当我们可以用抽象的术语给一个概念下一个精确的定义时，这个概念就被明显地理解了。在这里，专业的逻辑学家们跑题了，如果不是因为这是一个惊人的例子，我也不会拿他们的话来烦扰读者的，这表明逻辑学家们在智力活动的各个时代都在沉睡，无精打采地无视现代思想的造诣，从未梦想过把其教训应用于逻辑学的改进。不难看出，熟悉的使用和抽象的明确性使理解力更加完美的学说，在早已绝迹的哲学中才有独特的真正地位，现在是拟定达到更完美的清晰思维的方法的时候了，就像在我们这个时代的思想家身上看到和欣赏的那样。

当笛卡尔开始重建哲学时，他的第一步是在理论上允许怀疑主义，并抛弃了学派中把权威作为真理的最终来源的做法。这样一来，他就寻找到了真正原则的更自然的源泉，并认为他在人类的心灵中找到了它，得以最直接的方式，从权威的方法转向了的先验的方法，如我第一篇论文中所描述。自我意识为我们提供基本的真理，并判断什么是符合理性的。但是，由于显然不是所有的想法都是真的，他被引向关注把清晰作为无误的第一个条件，但他从来没有想过一个想法看起来清晰和真的清晰之间的区别。

正如他所做的那样，即使对于外部事物的知识，他也相信内省，为什么要质疑它对我们自己思想内容的证明呢？但是，我想，看到那些看起来非常清楚和积极的人，在基本原则上持有相反的意见，他又进一步说，思想的清晰性是不够的，它们还需要是明确的，也就是说，它们没有任何不明确之处。他的意思可能是（因为他没有准确解释），它们必须经得起辩证法的检验；它们不仅要在一开始就看起来很清楚，而且讨论必须永远不能使与它们有关的不明确之处暴露出来。

这就是笛卡尔的区别，人们看到，这正是他的哲学的水平，莱布尼茨在一定程度上发展了这一点。这位伟大而奇特的天才因为他没有看到的东西和他看到的东西一样引人注目，一件机械如果没有某种形式的动力供给，就不可能一直工作下去，这对他来说是一件非常明显的事情；但他不明白，思想的机械只能转化知识，而不能创造知识，除非它得到观察事实的供给。

因此，他错过了笛卡尔哲学最重要的一点，不能不接受不证自明的命题，无论它们是否符合逻辑。他没有这样看待这个问题，而是试图把科学的首要原则简化为两类，一类是在不自相矛盾的情况下不能否认的原则，另一类是由充分理由产生的原则（关于这一点，后面会提到），他显然没有意识到他的立场与笛卡尔的立场之间的巨大差异。所以他又恢复了逻辑学的旧有琐事，而且最重要的是，抽象的定义在他的哲学中起了很大作用。

因此，很自然的是，当他观察到笛卡尔的方法是在这样的困难下进行的，即我们可能对实际上非常模糊的概念在自己看来有清晰的理解，他没有想到比要求对每个重要术语进行抽象定义更好的补救办法了。因此，在采用清晰和明确的概念的区别时，他把后者的质量描述为对定义中所包含的一切的清晰理解，从那时起，书籍就一直在抄袭他的话。

没有任何危险，他的嵌合计划将再次被过度重视。通过分析定义，永远也学不到什么新东西。然而，我们现有的信念可以通过这个过程被安排得井井有条，而秩序是知识经济的一个基本要素，就像其他任何事物一样。因此，我们可以承认，作为实现清晰理解，这些书把熟悉一个概念作为第一步，把对它的定义作为第二步，这是正确的。但是，由于没有提到任何更高的思想敏锐性，它们只是反映了一种在一百年前就已经爆炸的哲学，那个备受推崇的“逻辑学的装饰品”—清晰和明确的学说--也许足够漂亮，但现在是时候把这个古老的璧人归入我们的奇珍异宝柜，并在我们身上佩戴一些更适合现代用途的东西了。

我们有权利要求逻辑学教给我们的第一课是，如何使我们的思想清晰，这是最重要的一课，只有那些需要它的头脑才贬低它。了解自己的想法，知道自己想说什么，将为深刻而严肃的思想打下坚实的基础。那些有简单和有限概念头脑的人最容易学到，比那些无助地沉浸在丰富的概念泥潭中的人要幸福得多。

诚然，一个民族可以在几代人的时间里，克服语言过于丰富以及自然伴随的—巨大的、深不可测的思想深度的缺点。我们可以在历史中看到，它在慢慢地完善其文学形式，削去它的形而上学，并且，凭借往往是一种补偿的不理想的耐心，在每一个方面都取得了精神巨大的成就。历史的一页还没有展开，告诉我们这样一个民族是否会在长期内战胜一个思想（就像他们的语言文字一样）不多，但却对它所拥有的那些思想拥有出色的掌握的民族。

然而，对于一个人来说，毫无疑问，几个清晰的想法比许多混乱的想法更有价值。一个年轻人很难被说服去牺牲他的大部分想法来拯救其余的想法；而头脑混乱的人最不容易看到这种牺牲的必要性。我们通常只能对他表示同情，就像对一个有先天缺陷的人表示同情一样。时间会帮助他，但智力上的成熟和清晰往往来得相当晚，这似乎是自然界的一个不幸的安排，因为对于一个在生活中安定下来的人，其错误已经在很大程度上产生了影响，而路就在他面前，清晰的作用就不大了。

可怕的是，一个不明确的想法，一个没有意义的公式，潜伏在一个年轻人的头脑中，有时会像动脉中的惰性物质阻塞一样，阻碍大脑的营养，使其受害者在智力充沛的时候，在智力丰富的时候憔悴。许多人多年来一直把一些模糊的想法作为自己的爱好，这些想法太无意义了，肯定是假的，但他还是热衷于此，日夜与它为伴，把自己的力量和生命交给它，为了它而放弃所有其他的职业，总之，与它生活在一起，为它而活，直到它成为他的肉中之肉，骨中之骨。然后在某个明亮的早晨他醒来，发现它消失了，像寓言中美丽的Melusina一样干净地消失了，他生命的精华也随之消失。我自己就认识这样一个人；谁能告诉我们，在这个古老的德国故事中，有多少圆规家、玄学家、占星家等人的历史没有被讲述？

附：

一，英语原文

https://courses.media.mit.edu/2004spring/mas966/Peirce%201878%20Make%20Ideas%20Clear.pdf

Whoever has looked into a modern treatise on logic of the common sort, will doubtless remember the two distinctions between clear and obscure conceptions, and between distinct and confused conceptions. They have lain in the books now for nigh two centuries, unimproved and unmodified, and are generally reckoned by logicians as among the gems of their doctrine.

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.

This is rather a neat bit of philosophical terminology; yet, since it is clearness that they were defining, I wish the logicians had made their definition a little more plain. Never to fail to recognize an idea, and under no circumstances to mistake another for it, let it come in how recondite a form it may, would indeed imply such prodigious force and clearness of intellect as is seldom met with in this world. On the other hand, merely 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.

A distinct idea is defined as one which contains nothing which is not clear. This is technical language; by the contents of an idea logicians understand whatever is contained in its definition. So that an idea is distinctly apprehended, according to them, when we can give a precise definition of it, in abstract terms. Here the professional logicians leave the subject; and I would not have troubled the reader with what they have to say, if it were not such a striking example of how they have been slumbering through ages of intellectual activity, listlessly disregarding the enginery of modern thought, and never dreaming of applying its lessons to the improvement of logic. It is easy to show that the doctrine that familiar use and abstract distinctness make the perfection of apprehension has its only true place in philosophies which have long been extinct; and it is now time to formulate the method of attaining to a more perfect clearness of thought, such as we see and admire in the thinkers of our own time.

When Descartes set about the reconstruction of philosophy, his first step was to (theoretically) permit scepticism and to discard the practice of the schoolmen of looking to authority as the ultimate source of truth. That done, he sought a more natural fountain of true principles, and thought he found it in the human mind; thus passing, in the directest way, from the method of authority to that of apriority, as described in my first paper. Self-consciousness was to furnish us with our fundamental truths, and to decide what was agreeable to reason. But since, evidently, not all ideas are true, he was led to note, as the first condition of infallibility, that they must be clear. The distinction between an idea seeming clear and really being so, never occurred to him.

Trusting to introspection, as he did, even for a knowledge of external things, why should he question its testimony in respect to the contents of our own minds? But then, I suppose, seeing men, who seemed to be quite clear and positive, holding opposite opinions upon fundamental principles, he was further led to say that clearness of ideas is not sufficient, but that they need also to be distinct, i.e., to have nothing unclear about them. What he probably meant by this (for he did not explain himself with precision) was, that they must sustain the test of dialectical examination; that they must not only seem clear at the outset, but that discussion must never be able to bring to light points of obscurity connected with them.

Such was the distinction of Descartes, and one sees that it was precisely on the level of his philosophy. It was somewhat developed by Leibnitz. This great and singular genius was as remarkable for what he failed to see as for what he saw. That a piece of mechanism could not do work perpetually without being fed with power in some form, was a thing perfectly apparent to him; yet he did not understand that the machinery of the mind can only transform knowledge, but never originate it, unless it be fed with facts of observation.

He thus missed the most essential point of the Cartesian philosophy, which is, that to accept propositions which seem perfectly evident to us is a thing which, whether it be logical or illogical, we cannot help doing. Instead of regarding the matter in this way, he sought to reduce the first principles of science to two classes, those which cannot be denied without self-contradiction, and those which result from the principle of sufficient reason (of which more anon), and was apparently unaware of the great difference between his position and that of Descartes. So he reverted to the old trivialities of logic; and, above all, abstract definitions played a great part in his philosophy.

It was quite natural, therefore, that on observing that the method of Descartes labored under the difficulty that we may seem to ourselves to have clear apprehensions of ideas which in truth are very hazy, no better remedy occurred to him than to require an abstract definition of every important term. Accordingly, in adopting the distinction of clear and distinct notions, he described the latter quality as the clear apprehension of everything contained in the definition; and the books have ever since copied his words. 

There is no danger that his chimerical scheme will ever again be over-valued. Nothing new can ever be learned by analyzing definitions. Nevertheless, our existing beliefs can be set in order by this process, and order is an essential element of intellectual economy, as of every other. It may be acknowledged, therefore, that the books are right in making familiarity with a notion the first step toward clearness of apprehension, and the defining of it the second. But in omitting all mention of any higher perspicuity of thought, they simply mirror a philosophy which was exploded a hundred years ago. That much-admired "ornament of logic" -- the doctrine of clearness and distinctness -- may be pretty enough, but it is high time to relegate to our cabinet of curiosities the antique bijou, and to wear about us something better adapted to modern uses.

The very first lesson that we have a right to demand that logic shall teach us is, how to make our ideas clear; and a most important one it is, depreciated only by minds who stand in need of it. To know what we think, to be masters of our own meaning, will make a solid foundation for great and weighty thought. It is most easily learned by those whose ideas are meagre and restricted; and far happier they than such as wallow helplessly in a rich mud of conceptions. 

A nation, it is true, may, in the course of generations, overcome the disadvantage of an excessive wealth of language and its natural concomitant, a vast, unfathomable deep of ideas. We may see it in history, slowly perfecting its literary forms, sloughing at length its metaphysics, and, by virtue of the untirable patience which is often a compensation, attaining great excellence in every branch of mental acquirement. The page of history is not yet unrolled that is to tell us whether such a people will or will not in the long run prevail over one whose ideas (like the words of their language) are few, but which possesses a wonderful mastery over those which it has. 

For an individual, however, there can be no question that a few clear ideas are worth more than many confused ones. A young man would hardly be persuaded to sacrifice the greater part of his thoughts to save the rest; and the muddled head is the least apt to see the necessity of such a sacrifice. Him we can usually only commiserate, as a person with a congenital defect. Time will help him, but intellectual maturity with regard to clearness is apt to come rather late. This seems an unfortunate arrangement of Nature, inasmuch as clearness is of less use to a man settled in life, whose errors have in great measure had their effect, than it would be to one whose path lay before him. 

It is terrible to see how a single unclear idea, a single formula without meaning, lurking in a young man's head, will sometimes act like an obstruction of inert matter in an artery, hindering the nutrition of the brain, and condemning its victim to pine away in the fullness of his intellectual vigor and in the midst of intellectual plenty. Many a man has cherished for years as his hobby some vague shadow of an idea, too meaningless to be positively false; he has, nevertheless, passionately loved it, has made it his companion by day and by night, and has given to it his strength and his life, leaving all other occupations for its sake, and in short has lived with it and for it, until it has become, as it were, flesh of his flesh and bone of his bone; and then he has waked up some bright morning to find it gone, clean vanished away like the beautiful Melusina of the fable, and the essence of his life gone with it. I have myself known such a man; and who can tell how many histories of circle- squarers, metaphysicians, astrologers, and what not, may not be told in the old German story?