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Theaetetus

It is this perverted form of the Heraclitean philosophy which is supposed to effect the final overthrow of Protagorean sensationalism. For if all things are changing at every moment, in all sorts of ways, then there is nothing fixed or defined at all, and therefore no sensible perception, nor any true word by which that or anything else can be described. Of course Protagoras would not have admitted the justice of this argument any more than Heracleitus would have acknowledged the 'uneducated fanatics' who appealed to his writings. He might have said, 'The excellent Socrates has first confused me with Heracleitus, and Heracleitus with his Ephesian successors, and has then disproved the existence both of knowledge and sensation. But I am not responsible for what I never said, nor will I admit that my common-sense account of knowledge can be overthrown by unintelligible Heraclitean paradoxes.'

IV. Still at the bottom of the arguments there remains a truth, that knowledge is something more than sensible perception; – this alone would not distinguish man from a tadpole. The absoluteness of sensations at each moment destroys the very consciousness of sensations (compare Phileb.), or the power of comparing them. The senses are not mere holes in a 'Trojan horse,' but the organs of a presiding nature, in which they meet. A great advance has been made in psychology when the senses are recognized as organs of sense, and we are admitted to see or feel 'through them' and not 'by them,' a distinction of words which, as Socrates observes, is by no means pedantic. A still further step has been made when the most abstract notions, such as Being and Not-being, sameness and difference, unity and plurality, are acknowledged to be the creations of the mind herself, working upon the feelings or impressions of sense. In this manner Plato describes the process of acquiring them, in the words 'Knowledge consists not in the feelings or affections (pathemasi), but in the process of reasoning about them (sullogismo).' Here, is in the Parmenides, he means something not really different from generalization. As in the Sophist, he is laying the foundation of a rational psychology, which is to supersede the Platonic reminiscence of Ideas as well as the Eleatic Being and the individualism of Megarians and Cynics.

V. Having rejected the doctrine that 'Knowledge is perception,' we now proceed to look for a definition of knowledge in the sphere of opinion. But here we are met by a singular difficulty: How is false opinion possible? For we must either know or not know that which is presented to the mind or to sense. We of course should answer at once: 'No; the alternative is not necessary, for there may be degrees of knowledge; and we may know and have forgotten, or we may be learning, or we may have a general but not a particular knowledge, or we may know but not be able to explain;' and many other ways may be imagined in which we know and do not know at the same time. But these answers belong to a later stage of metaphysical discussion; whereas the difficulty in question naturally arises owing to the childhood of the human mind, like the parallel difficulty respecting Not-being. Men had only recently arrived at the notion of opinion; they could not at once define the true and pass beyond into the false. The very word doxa was full of ambiguity, being sometimes, as in the Eleatic philosophy, applied to the sensible world, and again used in the more ordinary sense of opinion. There is no connexion between sensible appearance and probability, and yet both of them met in the word doxa, and could hardly be disengaged from one another in the mind of the Greek living in the fifth or fourth century B.C. To this was often added, as at the end of the fifth book of the Republic, the idea of relation, which is equally distinct from either of them; also a fourth notion, the conclusion of the dialectical process, the making up of the mind after she has been 'talking to herself' (Theat.).

We are not then surprised that the sphere of opinion and of Not-being should be a dusky, half-lighted place (Republic), belonging neither to the old world of sense and imagination, nor to the new world of reflection and reason. Plato attempts to clear up this darkness. In his accustomed manner he passes from the lower to the higher, without omitting the intermediate stages. This appears to be the reason why he seeks for the definition of knowledge first in the sphere of opinion. Hereafter we shall find that something more than opinion is required.

False opinion is explained by Plato at first as a confusion of mind and sense, which arises when the impression on the mind does not correspond to the impression made on the senses. It is obvious that this explanation (supposing the distinction between impressions on the mind and impressions on the senses to be admitted) does not account for all forms of error; and Plato has excluded himself from the consideration of the greater number, by designedly omitting the intermediate processes of learning and forgetting; nor does he include fallacies in the use of language or erroneous inferences. But he is struck by one possibility of error, which is not covered by his theory, viz. errors in arithmetic. For in numbers and calculation there is no combination of thought and sense, and yet errors may often happen. Hence he is led to discard the explanation which might nevertheless have been supposed to hold good (for anything which he says to the contrary) as a rationale of error, in the case of facts derived from sense.

Another attempt is made to explain false opinion by assigning to error a sort of positive existence. But error or ignorance is essentially negative – a not-knowing; if we knew an error, we should be no longer in error. We may veil our difficulty under figures of speech, but these, although telling arguments with the multitude, can never be the real foundation of a system of psychology. Only they lead us to dwell upon mental phenomena which if expressed in an abstract form would not be realized by us at all. The figure of the mind receiving impressions is one of those images which have rooted themselves for ever in language. It may or may not be a 'gracious aid' to thought; but it cannot be got rid of. The other figure of the enclosure is also remarkable as affording the first hint of universal all-pervading ideas, – a notion further carried out in the Sophist. This is implied in the birds, some in flocks, some solitary, which fly about anywhere and everywhere. Plato discards both figures, as not really solving the question which to us appears so simple: 'How do we make mistakes?' The failure of the enquiry seems to show that we should return to knowledge, and begin with that; and we may afterwards proceed, with a better hope of success, to the examination of opinion.

But is true opinion really distinct from knowledge? The difference between these he seeks to establish by an argument, which to us appears singular and unsatisfactory. The existence of true opinion is proved by the rhetoric of the law courts, which cannot give knowledge, but may give true opinion. The rhetorician cannot put the judge or juror in possession of all the facts which prove an act of violence, but he may truly persuade them of the commission of such an act. Here the idea of true opinion seems to be a right conclusion from imperfect knowledge. But the correctness of such an opinion will be purely accidental; and is really the effect of one man, who has the means of knowing, persuading another who has not. Plato would have done better if he had said that true opinion was a contradiction in terms.

Assuming the distinction between knowledge and opinion, Theaetetus, in answer to Socrates, proceeds to define knowledge as true opinion, with definite or rational explanation. This Socrates identifies with another and different theory, of those who assert that knowledge first begins with a proposition.

The elements may be perceived by sense, but they are names, and cannot be defined. When we assign to them some predicate, they first begin to have a meaning (onomaton sumploke logou ousia). This seems equivalent to saying, that the individuals of sense become the subject of knowledge when they are regarded as they are in nature in relation to other individuals.

Yet we feel a difficulty in following this new hypothesis. For must not opinion be equally expressed in a proposition? The difference between true and false opinion is not the difference between the particular and the universal, but between the true universal and the false. Thought may be as much at fault as sight. When we place individuals under a class, or assign to them attributes, this is not knowledge, but a very rudimentary process of thought; the first generalization of all, without which language would be impossible. And has Plato kept altogether clear of a confusion, which the analogous word logos tends to create, of a proposition and a definition? And is not the confusion increased by the use of the analogous term 'elements,' or 'letters'? For there is no real resemblance between the relation of letters to a syllable, and of the terms to a proposition.

Plato, in the spirit of the Megarian philosophy, soon discovers a flaw in the explanation. For how can we know a compound of which the simple elements are unknown to us? Can two unknowns make a known? Can a whole be something different from the parts? The answer of experience is that they can; for we may know a compound, which we are unable to analyze into its elements; and all the parts, when united, may be more than all the parts separated: e.g. the number four, or any other number, is more than the units which are contained in it; any chemical compound is more than and different from the simple elements. But ancient philosophy in this, as in many other instances, proceeding by the path of mental analysis, was perplexed by doubts which warred against the plainest facts.

Three attempts to explain the new definition of knowledge still remain to be considered. They all of them turn on the explanation of logos. The first account of the meaning of the word is the reflection of thought in speech – a sort of nominalism 'La science est une langue bien faite.' But anybody who is not dumb can say what he thinks; therefore mere speech cannot be knowledge. And yet we may observe, that there is in this explanation an element of truth which is not recognized by Plato; viz. that truth and thought are inseparable from language, although mere expression in words is not truth. The second explanation of logos is the enumeration of the elementary parts of the complex whole. But this is only definition accompanied with right opinion, and does not yet attain to the certainty of knowledge. Plato does not mention the greater objection, which is, that the enumeration of particulars is endless; such a definition would be based on no principle, and would not help us at all in gaining a common idea. The third is the best explanation, – the possession of a characteristic mark, which seems to answer to the logical definition by genus and difference. But this, again, is equally necessary for right opinion; and we have already determined, although not on very satisfactory grounds, that knowledge must be distinguished from opinion. A better distinction is drawn between them in the Timaeus. They might be opposed as philosophy and rhetoric, and as conversant respectively with necessary and contingent matter. But no true idea of the nature of either of them, or of their relation to one another, could be framed until science obtained a content. The ancient philosophers in the age of Plato thought of science only as pure abstraction, and to this opinion stood in no relation.

Like Theaetetus, we have attained to no definite result. But an interesting phase of ancient philosophy has passed before us. And the negative result is not to be despised. For on certain subjects, and in certain states of knowledge, the work of negation or clearing the ground must go on, perhaps for a generation, before the new structure can begin to rise. Plato saw the necessity of combating the illogical logic of the Megarians and Eristics. For the completion of the edifice, he makes preparation in the Theaetetus, and crowns the work in the Sophist.

Many (1) fine expressions, and (2) remarks full of wisdom, (3) also germs of a metaphysic of the future, are scattered up and down in the dialogue. Such, for example, as (1) the comparison of Theaetetus' progress in learning to the 'noiseless flow of a river of oil'; the satirical touch, 'flavouring a sauce or fawning speech'; or the remarkable expression, 'full of impure dialectic'; or the lively images under which the argument is described, – 'the flood of arguments pouring in,' the fresh discussions 'bursting in like a band of revellers.' (2) As illustrations of the second head, may be cited the remark of Socrates, that 'distinctions of words, although sometimes pedantic, are also necessary'; or the fine touch in the character of the lawyer, that 'dangers came upon him when the tenderness of youth was unequal to them'; or the description of the manner in which the spirit is broken in a wicked man who listens to reproof until he becomes like a child; or the punishment of the wicked, which is not physical suffering, but the perpetual companionship of evil (compare Gorgias); or the saying, often repeated by Aristotle and others, that 'philosophy begins in wonder, for Iris is the child of Thaumas'; or the superb contempt with which the philosopher takes down the pride of wealthy landed proprietors by comparison of the whole earth. (3) Important metaphysical ideas are: a. the conception of thought, as the mind talking to herself; b. the notion of a common sense, developed further by Aristotle, and the explicit declaration, that the mind gains her conceptions of Being, sameness, number, and the like, from reflection on herself; c. the excellent distinction of Theaetetus (which Socrates, speaking with emphasis, 'leaves to grow') between seeing the forms or hearing the sounds of words in a foreign language, and understanding the meaning of them; and d. the distinction of Socrates himself between 'having' and 'possessing' knowledge, in which the answer to the whole discussion appears to be contained.

…

There is a difference between ancient and modern psychology, and we have a difficulty in explaining one in the terms of the other. To us the inward and outward sense and the inward and outward worlds of which they are the organs are parted by a wall, and appear as if they could never be confounded. The mind is endued with faculties, habits, instincts, and a personality or consciousness in which they are bound together. Over against these are placed forms, colours, external bodies coming into contact with our own body. We speak of a subject which is ourselves, of an object which is all the rest. These are separable in thought, but united in any act of sensation, reflection, or volition. As there are various degrees in which the mind may enter into or be abstracted from the operations of sense, so there are various points at which this separation or union may be supposed to occur. And within the sphere of mind the analogy of sense reappears; and we distinguish not only external objects, but objects of will and of knowledge which we contrast with them. These again are comprehended in a higher object, which reunites with the subject. A multitude of abstractions are created by the efforts of successive thinkers which become logical determinations; and they have to be arranged in order, before the scheme of thought is complete. The framework of the human intellect is not the peculium of an individual, but the joint work of many who are of all ages and countries. What we are in mind is due, not merely to our physical, but to our mental antecedents which we trace in history, and more especially in the history of philosophy. Nor can mental phenomena be truly explained either by physiology or by the observation of consciousness apart from their history. They have a growth of their own, like the growth of a flower, a tree, a human being. They may be conceived as of themselves constituting a common mind, and having a sort of personal identity in which they coexist.

So comprehensive is modern psychology, seeming to aim at constructing anew the entire world of thought. And prior to or simultaneously with this construction a negative process has to be carried on, a clearing away of useless abstractions which we have inherited from the past. Many erroneous conceptions of the mind derived from former philosophies have found their way into language, and we with difficulty disengage ourselves from them. Mere figures of speech have unconsciously influenced the minds of great thinkers. Also there are some distinctions, as, for example, that of the will and of the reason, and of the moral and intellectual faculties, which are carried further than is justified by experience. Any separation of things which we cannot see or exactly define, though it may be necessary, is a fertile source of error. The division of the mind into faculties or powers or virtues is too deeply rooted in language to be got rid of, but it gives a false impression. For if we reflect on ourselves we see that all our faculties easily pass into one another, and are bound together in a single mind or consciousness; but this mental unity is apt to be concealed from us by the distinctions of language.

A profusion of words and ideas has obscured rather than enlightened mental science. It is hard to say how many fallacies have arisen from the representation of the mind as a box, as a 'tabula rasa,' a book, a mirror, and the like. It is remarkable how Plato in the Theaetetus, after having indulged in the figure of the waxen tablet and the decoy, afterwards discards them. The mind is also represented by another class of images, as the spring of a watch, a motive power, a breath, a stream, a succession of points or moments. As Plato remarks in the Cratylus, words expressive of motion as well as of rest are employed to describe the faculties and operations of the mind; and in these there is contained another store of fallacies. Some shadow or reflection of the body seems always to adhere to our thoughts about ourselves, and mental processes are hardly distinguished in language from bodily ones. To see or perceive are used indifferently of both; the words intuition, moral sense, common sense, the mind's eye, are figures of speech transferred from one to the other. And many other words used in early poetry or in sacred writings to express the works of mind have a materialistic sound; for old mythology was allied to sense, and the distinction of matter and mind had not as yet arisen. Thus materialism receives an illusive aid from language; and both in philosophy and religion the imaginary figure or association easily takes the place of real knowledge.

Again, there is the illusion of looking into our own minds as if our thoughts or feelings were written down in a book. This is another figure of speech, which might be appropriately termed 'the fallacy of the looking-glass.' We cannot look at the mind unless we have the eye which sees, and we can only look, not into, but out of the mind at the thoughts, words, actions of ourselves and others. What we dimly recognize within us is not experience, but rather the suggestion of an experience, which we may gather, if we will, from the observation of the world. The memory has but a feeble recollection of what we were saying or doing a few weeks or a few months ago, and still less of what we were thinking or feeling. This is one among many reasons why there is so little self-knowledge among mankind; they do not carry with them the thought of what they are or have been. The so-called 'facts of consciousness' are equally evanescent; they are facts which nobody ever saw, and which can neither be defined nor described. Of the three laws of thought the first (All A = A) is an identical proposition – that is to say, a mere word or symbol claiming to be a proposition: the two others (Nothing can be A and not A, and Everything is either A or not A) are untrue, because they exclude degrees and also the mixed modes and double aspects under which truth is so often presented to us. To assert that man is man is unmeaning; to say that he is free or necessary and cannot be both is a half truth only. These are a few of the entanglements which impede the natural course of human thought. Lastly, there is the fallacy which lies still deeper, of regarding the individual mind apart from the universal, or either, as a self-existent entity apart from the ideas which are contained in them.

In ancient philosophies the analysis of the mind is still rudimentary and imperfect. It naturally began with an effort to disengage the universal from sense – this was the first lifting up of the mist. It wavered between object and subject, passing imperceptibly from one or Being to mind and thought. Appearance in the outward object was for a time indistinguishable from opinion in the subject. At length mankind spoke of knowing as well as of opining or perceiving. But when the word 'knowledge' was found how was it to be explained or defined? It was not an error, it was a step in the right direction, when Protagoras said that 'Man is the measure of all things,' and that 'All knowledge is perception.' This was the subjective which corresponded to the objective 'All is flux.' But the thoughts of men deepened, and soon they began to be aware that knowledge was neither sense, nor yet opinion – with or without explanation; nor the expression of thought, nor the enumeration of parts, nor the addition of characteristic marks. Motion and rest were equally ill adapted to express its nature, although both must in some sense be attributed to it; it might be described more truly as the mind conversing with herself; the discourse of reason; the hymn of dialectic, the science of relations, of ideas, of the so-called arts and sciences, of the one, of the good, of the all: – this is the way along which Plato is leading us in his later dialogues. In its higher signification it was the knowledge, not of men, but of gods, perfect and all sufficing: – like other ideals always passing out of sight, and nevertheless present to the mind of Aristotle as well as Plato, and the reality to which they were both tending. For Aristotle as well as Plato would in modern phraseology have been termed a mystic; and like him would have defined the higher philosophy to be 'Knowledge of being or essence,' – words to which in our own day we have a difficulty in attaching a meaning.

Yet, in spite of Plato and his followers, mankind have again and again returned to a sensational philosophy. As to some of the early thinkers, amid the fleetings of sensible objects, ideas alone seemed to be fixed, so to a later generation amid the fluctuation of philosophical opinions the only fixed points appeared to be outward objects. Any pretence of knowledge which went beyond them implied logical processes, of the correctness of which they had no assurance and which at best were only probable. The mind, tired of wandering, sought to rest on firm ground; when the idols of philosophy and language were stripped off, the perception of outward objects alone remained. The ancient Epicureans never asked whether the comparison of these with one another did not involve principles of another kind which were above and beyond them. In like manner the modern inductive philosophy forgot to enquire into the meaning of experience, and did not attempt to form a conception of outward objects apart from the mind, or of the mind apart from them. Soon objects of sense were merged in sensations and feelings, but feelings and sensations were still unanalyzed. At last we return to the doctrine attributed by Plato to Protagoras, that the mind is only a succession of momentary perceptions. At this point the modern philosophy of experience forms an alliance with ancient scepticism.

The higher truths of philosophy and religion are very far removed from sense. Admitting that, like all other knowledge, they are derived from experience, and that experience is ultimately resolvable into facts which come to us through the eye and ear, still their origin is a mere accident which has nothing to do with their true nature. They are universal and unseen; they belong to all times – past, present, and future. Any worthy notion of mind or reason includes them. The proof of them is, 1st, their comprehensiveness and consistency with one another; 2ndly, their agreement with history and experience. But sensation is of the present only, is isolated, is and is not in successive moments. It takes the passing hour as it comes, following the lead of the eye or ear instead of the command of reason. It is a faculty which man has in common with the animals, and in which he is inferior to many of them. The importance of the senses in us is that they are the apertures of the mind, doors and windows through which we take in and make our own the materials of knowledge. Regarded in any other point of view sensation is of all mental acts the most trivial and superficial. Hence the term 'sensational' is rightly used to express what is shallow in thought and feeling.

We propose in what follows, first of all, like Plato in the Theaetetus, to analyse sensation, and secondly to trace the connexion between theories of sensation and a sensational or Epicurean philosophy.

Paragraph I. We, as well as the ancients, speak of the five senses, and of a sense, or common sense, which is the abstraction of them. The term 'sense' is also used metaphorically, both in ancient and modern philosophy, to express the operations of the mind which are immediate or intuitive. Of the five senses, two – the sight and the hearing – are of a more subtle and complex nature, while two others – the smell and the taste – seem to be only more refined varieties of touch. All of them are passive, and by this are distinguished from the active faculty of speech: they receive impressions, but do not produce them, except in so far as they are objects of sense themselves.

Physiology speaks to us of the wonderful apparatus of nerves, muscles, tissues, by which the senses are enabled to fulfil their functions. It traces the connexion, though imperfectly, of the bodily organs with the operations of the mind. Of these latter, it seems rather to know the conditions than the causes. It can prove to us that without the brain we cannot think, and that without the eye we cannot see: and yet there is far more in thinking and seeing than is given by the brain and the eye. It observes the 'concomitant variations' of body and mind. Psychology, on the other hand, treats of the same subject regarded from another point of view. It speaks of the relation of the senses to one another; it shows how they meet the mind; it analyzes the transition from sense to thought. The one describes their nature as apparent to the outward eye; by the other they are regarded only as the instruments of the mind. It is in this latter point of view that we propose to consider them.

The simplest sensation involves an unconscious or nascent operation of the mind; it implies objects of sense, and objects of sense have differences of form, number, colour. But the conception of an object without us, or the power of discriminating numbers, forms, colours, is not given by the sense, but by the mind. A mere sensation does not attain to distinctness: it is a confused impression, sugkechumenon ti, as Plato says (Republic), until number introduces light and order into the confusion. At what point confusion becomes distinctness is a question of degree which cannot be precisely determined. The distant object, the undefined notion, come out into relief as we approach them or attend to them. Or we may assist the analysis by attempting to imagine the world first dawning upon the eye of the infant or of a person newly restored to sight. Yet even with them the mind as well as the eye opens or enlarges. For all three are inseparably bound together – the object would be nowhere and nothing, if not perceived by the sense, and the sense would have no power of distinguishing without the mind.

But prior to objects of sense there is a third nature in which they are contained – that is to say, space, which may be explained in various ways. It is the element which surrounds them; it is the vacuum or void which they leave or occupy when passing from one portion of space to another. It might be described in the language of ancient philosophy, as 'the Not-being' of objects. It is a negative idea which in the course of ages has become positive. It is originally derived from the contemplation of the world without us – the boundless earth or sea, the vacant heaven, and is therefore acquired chiefly through the sense of sight: to the blind the conception of space is feeble and inadequate, derived for the most part from touch or from the descriptions of others. At first it appears to be continuous; afterwards we perceive it to be capable of division by lines or points, real or imaginary. By the help of mathematics we form another idea of space, which is altogether independent of experience. Geometry teaches us that the innumerable lines and figures by which space is or may be intersected are absolutely true in all their combinations and consequences. New and unchangeable properties of space are thus developed, which are proved to us in a thousand ways by mathematical reasoning as well as by common experience. Through quantity and measure we are conducted to our simplest and purest notion of matter, which is to the cube or solid what space is to the square or surface. And all our applications of mathematics are applications of our ideas of space to matter. No wonder then that they seem to have a necessary existence to us. Being the simplest of our ideas, space is also the one of which we have the most difficulty in ridding ourselves. Neither can we set a limit to it, for wherever we fix a limit, space is springing up beyond. Neither can we conceive a smallest or indivisible portion of it; for within the smallest there is a smaller still; and even these inconceivable qualities of space, whether the infinite or the infinitesimal, may be made the subject of reasoning and have a certain truth to us.