Notes on Bertrand Russell s The Problems of Philosophy (Hackett 1990 reprint of the 1912 Oxford edition, Chapters XII, XIII, XIV, )

Transcription

1 Notes on Bertrand Russell s The Problems of Philosophy (Hackett 1990 reprint of the 1912 Oxford edition, Chapters XII, XIII, XIV, ) Chapter XII Truth and Falsehood [pp ] Russell begins here [on p. 119] by pointing out that We may believe what is false as well as what is true. We know that on very many subjects different people hold different and incompatible opinions: hence some beliefs must be erroneous. Two Questions: Russell distinguishes between two questions concerning truth and falsity: 1. How are false beliefs to be distinguished from true beliefs? 2. What do we mean by truth and falsity? In this section on Truth and Falsehood, Russell concentrates on the second question. He argues that a satisfactory theory of the nature of truth must meet three requirements: 1. A satisfactory theory of truth must include an explanation of the opposite of truth, i.e., falsity. 2. A satisfactory theory of truth must recognize that truth and falsity are properties of beliefs and statements. Only beliefs and statements, which are mental constructions, can be either true or false. Material things and other such facts are neither true nor false. 3. A satisfactory theory of truth must acknowledge that the truth or falsity of a belief is completely dependent on the relation of the belief to something (some fact or set of facts) outside of the belief itself. This requirement leads Russell to adopt the so-called correspondence theory of truth, i.e., the theory which holds that a belief or statement is true when it corresponds to the facts and false when it does not. Critique of the Coherence Theory of Truth Russell then focuses on and criticizes the so-called coherence theory of truth, a theory which some philosophers have developed as an alternative to the correspondence theory. The coherence theory of truth is the view that a true belief or statement is one that is part of a completely developed and logically consistent system of truths, whereas a belief or statement is false when it fails to be coherent with that system. 1

2 Russell presents two objections to the coherence theory of truth: 1. More than just one coherent body of beliefs about reality is possible. He gives examples from literature, science, and philosophy that show that there is no good reason to believe that there can be only one coherent system of beliefs. In fact, it seems obvious that there are more than one such set of beliefs. 2. The coherence theory of truth presupposes and depends on the correctness of the laws of logic, e.g., the law of non-contradiction, which says that two contradictory statements cannot be true or false together (one must be true, and the other must be false). If this tree is a beech is true, then this tree is not a beech must be false, and vice-versa. Russell s main point here is that such laws of logic cannot themselves be established by the coherence test. For example, if the law of [non-]contradiction itself were subjected to the test of coherence, we should find that, if we choose to suppose it false, nothing will any longer be incoherent with anything else. The laws of logic are the presupposed basis of what is meant by coherence. They define coherence; coherence does not define them. Relations and Facts So Russell holds to the theory that truth is correspondence of belief (or statement, or judgment) with fact. Since the truth or falsity of a belief or statement (or judgment) depends upon its relation to facts outside of itself, Russell must go into the nature of relations and the nature of facts. 1. He begins [in a very obscure section on p. 124] by arguing that we cannot regard belief as a relation of the mind to a single object, which could be said to be what is believed. If Othello believes that Desdemona loves Cassio when she doesn t, Othello s belief cannot be related to the single object, Desdemona s love for Cassio. If such an object existed, then Othello s belief would have to be true. But if Desdemona, in fact, does NOT love Cassio, then there is no such object as Desdemona s love for Cassio and Othello s belief that Desdemona loves Cassio cannot have any relation to such an object. Thus, Russell states that we must look for a theory which does not define belief as a relation of the mind to a single object. 2. In the next paragraph on p. 124, Russell points out that there are relations which require more than two terms before they can occur. He goes on [in the following paragraphs] to show that the relation involved in judging or believing must, if falsehood is to be duly allowed for, be taken to be a relation between several terms, not between two. He argues that Othello s belief that Desdemona loves Cassio contains four terms: (1) Othello s mind, (2) Desdemona, (3) loving, and (4) Cassio. When Othello believes or judges that Desdemona loves Cassio, the act of believing or judging knits the four terms together into one complex whole, which is structured as follows:! There is a mind (subject) which judges, and there are terms which are the objects of the mind s judgment. When Othello judges that Desdemona loves Cassio, Othello is the subject, and the objects are Desdemona and loving and Cassio. 2

3 ! The subject and the objects are the constituents of the judgment.! The relation of judging has a sense or direction, i.e., a certain order, which follows the order of the words in the sentence. The following judgments all have the same constituents, but they do not have the same order (sense): " Othello judges that Cassio loves Desdemona. " Othello judges that Desdemona loves Cassio. " Cassio judges that Desdemona loves Othello. " Etc.! The act of judging or believing knits its constituents (the subject and the objects) together into one complex whole [and this complex whole exists].! Whenever a relation holds between two or more terms, it unites the terms into a complex whole. If Othello loves Desdemona, there is such a complex whole as Othello s love for Desdemona. Wherever there is a relation which relates certain terms, there is a complex object formed of the union of those terms; conversely, wherever there is a complex object, there is a relation which relates its constituents.! In an act of believing or judging, there is a complex, in which believing or judging is the uniting relation, and subject and objects are arranged in a certain order by the sense of the relation of believing.! Among the objects of judgment or belief, one must be a relation e.g., loving. But this relation, as it occurs in the act of believing, is not the relation which creates the unity of the complex whole consisting of the subject and the objects. The relation loving, as it occurs in the act of believing, is one of the objects it is a brick in the structure, not the cement. The cement is the relation believing. Russell s Version of the Correspondence Theory of Truth Now Russell is ready to define the differences between true and false beliefs (judgments). He states his view in several alternative ways:! When a belief is true, there exists a complex unity external to the belief, in which the relation which is one of the objects of the belief relates the other objects. For example, if Othello s belief that Desdemona loves Cassio is true, then there exists a complex unity, Desdemona s love for Cassio, which is composed exclusively of the objects of the belief, in the same order they have in the belief, with the relation which is one of the objects [loving] functioning now as the cement that binds together the other objects of the belief. When a belief is false, there is no such complex unity 3

4 composed only of the objects of the belief. If Othello s belief that Desdemona loves Cassio is false, then there is no such complex unity as Desdemona s love for Cassio.! A belief is true when it corresponds to a certain associated objective (actually existing) complex, and false when it does not. In a case where the objects of the belief are two terms (Desdemona and Cassio) and a relation (loving), and where the terms are placed in a certain order by the sense of the believing, then if the two terms in that order are united by the relation into a complex, the belief is true; if not, it is false. That is, if Desdemona s love for Cassio actually exists, then the belief that Desdemona loves Cassio is true; whereas if Desdemona s love for Cassio does not exist, then the belief that Desdemona loves Cassio is false.! Judging or believing is a certain complex unity of which a mind is a constituent; if the remaining constituents, taken in the order which they have in the belief, form a complex unity [i.e., if the object of the belief actually exists], then the belief is true; if not, it is false.! In the belief, Othello believes that Desdemona loves Cassio, Desdemona and Cassio are the object-terms, and loving is the object-relation. If there is a complex unity, Desdemona s love for Cassio, consisting of the object-terms related by the object-relation in the same order as they have in the belief, then this complex unity is the fact corresponding to the belief. A belief is true when there is such a corresponding fact, and is false when there is no such corresponding fact. The Objective Basis of Truth and Falsity As part of his theory of truth and falsity, Russell emphasizes that beliefs are true or false depending on what the objective facts are. Here are two quotations from pp :! Thus although truth and falsity are properties of beliefs, yet they are in a sense extrinsic properties, for the condition of the truth of a belief is something not involving beliefs, or (in general) any mind at all, but only the objects of the belief. A mind that believes, believes truly when there exists a corresponding complex not involving the mind, but only its objects. This correspondence ensures truth, and its absence entails falsehood. Hence we account simultaneously for the two facts that beliefs (a) depend on minds for their existence, (b) do not depend on minds for their truth. (129)! It will be seen that minds do not create truth or falsity. They create beliefs, but when once the beliefs are created, the mind cannot make them true or false, except in the special case where they concern future things which are within the power of the person believing, such as catching trains. What makes a belief true is a fact, and this fact does not (except in exceptional cases) in any way involve the mind of the person who has the belief. ( ) 4

5 Beliefs depend for their truth or falsity on objects existing outside of the mind. Truth and falsity are not subjectively created. Chapter XIII Knowledge, Error, and Probable Opinion [pp ] Russell now turns to the following questions: What ways are there of knowing whether this or that belief is true or false? How can we know what is true and what is false? What certainty can we ever have that such and such a belief is not erroneous? Can we ever know anything at all, or do we merely sometimes by good luck believe what is true? In order to answer those questions, we must first decide what knowledge is. Knowledge Is Not True Belief! Knowledge cannot be defined as true belief. It is possible to validly deduce a true belief from false beliefs. For example: All dogs are cats (false), and all tigers are dogs (false); therefore, all tigers are cats (true). (Note Russell s examples here.) If the basis of my true belief that all tigers are cats are those false premises, then my true belief does not constitute knowledge.! Also, it is possible to arrive at a true belief through a process of fallacious reasoning from true premises: e.g., all Greeks are human (true), and Socrates was human (true); therefore, Socrates was a Greek (true). The true conclusion does not follow logically from the true premises. If I believe that Socrates was a Greek on this basis, then I do not know that Socrates was a Greek. The Distinction Between Derivative and Intuitive Knowledge Russell also argues that we cannot say that knowledge is belief that is validly deduced from true premises. That definition of knowledge is too wide (takes in too much) because it includes valid inferences from premises that are true but not known to be true. [Example: If extraterrestrials exist, then we are not alone in the universe. Extraterrestrials exist. Therefore, we are not alone in the universe. This is a valid argument, and the first premise is true, but does anyone know whether the second premise is true or false? If we don t know that extraterrestrials exist, even though it is possible that they do, then we do not know that we are not alone in the universe.] Thus, Russell concludes that [one kind of] knowledge is belief that is validly deduced from known premises. 5

6 However, the latter definition is too narrow (excludes too much) because it does not include intuitive knowledge, i.e., immediate knowledge not derived from a process of inference. According to Russell, there are two kinds of knowledge: 1. Derivative knowledge = knowledge that is deduced [inferred] validly from premises that are known intuitively to be true. 2. Intuitive knowledge = direct or immediate knowledge not derived from a process of inference; knowledge of self-evident truths. Before explaining more fully what he means by intuitive knowledge, Russell adds the following points to his definition of derivative knowledge.... Derivative Knowledge Includes Knowledge Derived from Psychological Inference When we define derivative knowledge as knowledge that is deduced [inferred] validly from premises that are known intuitively to be true, we must recognize that, very often, people hold a true belief on the basis of some piece of intuitive knowledge from which it is capable of being validly inferred, but from which it has not, as a matter of fact, been inferred by any logical process (133). Russell presents the following example, which describes the process by which beliefs are derived from reading newspapers: Take, for example, the beliefs produced by reading. If the newspapers announce the death of the King, we are fairly well justified in believing that the King is dead, since this is the sort of announcement which would not be made if it were false. And we are quite amply justified in believing that the newspaper asserts that the King is dead. But here the intuitive knowledge upon which our belief is based is knowledge of the existence of sense-data derived from looking at the print which gives the news. This knowledge scarcely rises into consciousness, except in a person who cannot read easily. A child may be aware of the shapes of the letters, and pass gradually and painfully to a realization of their meaning. But anybody accustomed to reading passes at once to what the letters mean, and is not aware, except on reflection, that he has derived this knowledge from the sense-data called seeing the printed letters. Thus although a valid inference from the letters to their meaning is possible, and could be performed by the reader, it is not in fact performed, since he does not in fact perform any operation which can be called logical inference. Yet it would be absurd to say that the reader does not know that the newspaper announces the King s death. ( ) [emphasis added] On this basis, Russell concludes that we must admit as derivative knowledge whatever is the result of intuitive knowledge even if by mere association, provided there is a valid logical connection, and the person in question could become aware of this connection by reflection (274). He calls this not-strictly-logical process psychological inference. It counts as a way of acquiring derivative knowledge so long as there is a discoverable logical inference which runs parallel to the psychological inference (134). 6

7 Intuitive Knowledge: Knowledge of Self-Evident Truths How can we distinguish between true and false intuitive beliefs? Russell seems to define intuitive knowledge as the direct apprehension of self-evident truths. A self-evident truth (as its name implies) is obviously true, in and of itself. No argument is necessary to establish its truth. It is known [seen?] to be true through direct comprehension (intuition). According to Russell, there are basically two ways in which any complex fact [e.g., Desdemona s love for Othello] may be known: 1. A complex fact can be known by means of a judgment, in which the several parts of the complex fact are judged to be related as they are in fact related (so that the judgment corresponds to the fact) [e.g., Cassio judges that Desdemona loves Othello]. With judgments, error is possible. As it happens, Cassio would be right in judging that Desdemona loves Othello, but his judgment could be wrong if, in fact, Desdemona did not love Othello. 2. A complex fact can be known by means of acquaintance with the complex fact itself, which may be called perception (including mental as well as sensual perception) [e.g., Desdemona knows through her direct acquaintance with her own feelings that she loves Othello; I see that my desk phone appears to be to the left of my desk lamp; etc.]. Knowing a complex fact by acquaintance (direct perception) is possible only when there really is such a fact, only when the parts of the complex do actually have that relation which makes them combine to form such a complex. Two Kinds of Self-Evidence Russell holds that there are two kinds of self-evidence: 1. The first kind of self-evidence gives us an absolute guarantee of truth. This arises when we are acquainted with the fact which corresponds to the truth.! Acquaintance with mental facts and facts concerning sense-data is completely private: I alone am acquainted with my own thoughts and sensations. Only Desdemona can know on the basis of acquaintance whether she loves Othello or not, and the truth here could be self-evident only to her and to no one else.! In addition to our own ideas and sensations, we are also acquainted with universals i.e., general concepts (rather than particular percepts) such as the color blue, the numbers two and four, the relation to the left of, and so on. Acquaintance with universals is not private. Many minds may be acquainted with the same universals; hence a relation between universals may be known by acquaintance to many different people (137). 7

8 When we know by acquaintance a complex fact consisting of certain terms in a certain relation [e.g., two plus two equal four ], the truth that these terms are so related is absolutely self-evident; the judgment that the terms are so related must be true. This kind of self-evidence gives us an absolute guarantee of truth. However, this does not guarantee that any given judgment is true. Russell presents the following example: Suppose we first perceive the sun shining, which is a complex fact, and thence proceed to make the judgment the sun is shining. In passing from the perception to the judgment, it is necessary to analyze the given complex fact: we have to separate out the sun and shining as constituents of the fact. In this process it is possible to commit an error; hence even where a fact has the first or absolute kind of selfevidence, a judgment believed to correspond to the fact is not absolutely infallible, because it may not really correspond to the fact. But if it does correspond (in the sense explained in the preceding chapter), then it must be true. ( ) 2. There is a second kind of self-evidence that gives only a partial guarantee of truth. This kind is not derived from direct acquaintance with or perception of a fact as a single complex whole, but is rather associated with judgments based on experiences of gradation. Here, there are various degrees of self-evidence. Russell gives the following examples (on p. 138):! Take, for example, the case of a horse trotting away from us along a hard road. At first our certainty that we hear the hoofs is complete; gradually, if we listen intently, there comes a moment when we think perhaps it was imagination or the blind upstairs or our own heartbeats; at last we become doubtful whether there was any noise at all; then we think we no longer hear anything, and at last we know we no longer hear anything. In this process, there is a continual gradation of self-evidence, from the highest degree to the least, not in the sense-data themselves, but in the judgments based on them.! Or again: Suppose we are comparing two shades of color, one blue and one green. We can be quite sure they are different shades of color; but if the green color is gradually altered to be more and more like the blue, becoming first a blue-green, then a greeny-blue, then blue, there will come a moment when we are doubtful whether we can see any difference, and then a moment when we know that we cannot see any difference.! The same thing happens in tuning a musical instrument, or in any other case where there is a continuous gradation. In situations like these, self-evidence is a matter of degree; and the higher degrees are more trustworthy than the lower degrees. 8

9 Derivative Knowledge and Self-Evidence At this point (p. 139), Russell returns to the concept of derivative [inferential] knowledge. For knowledge to be derived from a process of reasoning or inference, the premises of an argument must have some degree of self-evidence and so must their connection with the conclusions inferred from them. Russell comments: Take for example a piece of reasoning in geometry. It is not enough that the axioms from which we start should be self-evident: it is necessary also that, at each step in the reasoning, the connection of premise and conclusion should be self-evident. He then adds: In difficult reasoning, this connection [between premises and conclusion] has often only a very small degree of self-evidence; hence errors of reasoning are not improbable where the difficulty is great. Knowledge, Error, and Probable Opinion Russell makes the distinction between knowledge, error, and probable opinion as follows: 1. What we firmly believe, if it is true, is called knowledge, provided it is either intuitive or inferred (logically or psychologically) from intuitive knowledge from which it follows logically. 2. What we firmly believe, if it is not true, is called error. 3. What we firmly believe, if it is neither knowledge nor error, and also what we believe hesitatingly, because it is, or is derived from, something which has not the highest degree of self-evidence, may be called probable opinion. Russell holds that most of what we take to be knowledge is actually more or less probable opinion. Probable Opinion and the Coherence Criterion In his earlier discussion of Truth and Falsehood [the first section of our reading], Russell rejected coherence as the definition of truth, but in this context he accepts coherence as a criterion of truth. His general point is the following: A body of individually probable opinions, if they are mutually coherent, become more probable than any one of them would be individually (140).! Many scientific hypotheses acquire their probability by fitting into a coherent system of probable opinions. Thus, they become more probable than they would be in isolation.! This also the case with general philosophical hypotheses. Often in a single case such hypotheses may seem highly doubtful, while yet, when we consider the order and coherence which they introduce into a mass of probable opinion, they become pretty nearly certain. This applies, in particular, to such matters as the distinction between dreams and waking life. If our dreams, night after night, were as coherent one with 9

10 another as our days, we should hardly know whether to believe the dreams or the waking life. As it is, the test of coherence condemns the dreams and confirms the waking life. However, while the coherence test can make various beliefs seem more probable, it never leads us to absolute certainty ( unless [Russell writes] there is certainty already at some point in the coherent system ). Probability, no matter how high the degree, can never bring us to indubitable knowledge. Chapter XIV The Limits of Philosophical Knowledge [pp ] In this section, Russell tries to show that there can be no knowledge of the nature of the universe as a whole and that traditional philosophical attempts to prove such things as the fundamental dogmas of religion, the essential rationality of the universe, the illusoriness of matter, the unreality of all evil, and so on cannot succeed. Criticism of Hegel s Philosophy Russell uses G.W.F. Hegel ( ) as an example of a philosopher who sought to figure out the whole of reality via a priori metaphysical reasoning. Hegel s overall metaphysical view: Hegel s main thesis is that everything less than the totality of being is fragmentary and incapable of existing on it own. To grasp the nature of reality as a whole, the metaphysician must begin with a fragment of reality and trace it to the next fragment, which must then be traced to the next fragment, and so on, until the whole universe is reconstructed. For Hegel, both things and thoughts are incomplete and fragmentary in this way. Russell focuses on the way in which Hegel sees the process by which thought can move to higher and higher levels:... [I]f we take any idea which is abstract or incomplete, we find, on examination, that if we forget its incompleteness, we become involved in contradictions; these contradictions turn the idea in question into its opposite, or antithesis; and in order to escape, we have to find a new, less incomplete idea, which is the synthesis of our original idea and its antithesis. This new idea, though less incomplete than the idea we started with, will be found, nevertheless, to be still not wholly complete, but to pass into its antithesis, with which it must be combined in a new synthesis. In this way Hegel advances until he reaches the Absolute Idea, which, according to him, has no incompleteness, no opposite, and no need of further 10

11 development. The Absolute Idea, therefore, is adequate to describe Absolute Reality; but all lower ideas only describe reality as it appears to a partial view, not as it is to one who simultaneously surveys the Whole. Thus Hegel reaches the conclusion that Absolute Reality forms one single harmonious system, not in space or time, not in any degree evil, wholly rational, and wholly spiritual. Any appearance to the contrary, in the world we know, can be proved logically so he believes to be entirely due to our fragmentary piecemeal view of the universe. If we saw the universe whole, as we may suppose God sees it, space and time and matter and evil and all striving and struggling would disappear, and we should see instead an eternal perfect unchanging spiritual unity. ( ) Hegel s fundamental tenet : According to Hegel, something that is incomplete cannot exist in and of itself. Its existence depends upon the support of other things. Explaining this, Russell writes: Russell s criticism of Hegel: [W]hatever has relations to things outside itself must contain some reference to those outside things in its own nature, and could not, therefore, be what it is if those outside things did not exist. A man s nature, for example, is constituted by his memories and the rest of his knowledge, by his loves and hatreds, and so on; thus, but for the objects which he knows or loves or hates, he could not be what he is. He is essentially and obviously a fragment: taken as the sumtotal of reality he would be self-contradictory. (143) According to Russell, Hegel s view of reality is based on the notion of the nature of a thing, which Russell interprets to mean all the truths about the thing. Russell acknowledges that a truth which connects one thing with another thing could not exist if the other thing did not exist. But he argues that a truth about a thing is not part of the thing itself. Russell thinks that there is something wrong with Hegel s conception of the nature of a thing. If the nature of a thing is all the truths about the thing, then what Hegel says would be correct: we would not be able to know a thing s nature unless we knew all of the thing s relations to all the other things in the universe. However, according to Russell, Hegel s use of the word nature leads to a contradiction: namely, that we can know a thing without knowing (or knowing completely) its nature. Hegel s concept of the 11

12 nature of a thing as all the truths about the thing confuses two different kinds of knowledge: knowledge of things and knowledge of truths. We know a thing by acquaintance even if we know very few (or perhaps no) propositions (truths) about it. Acquaintance with a thing does not include knowledge of its nature in Hegel s sense. Also, we may know one truth about something with which we are acquainted without knowing all the truths about the thing, which means that, for Hegel, we would not know the nature of the thing. Russell concludes (against Hegel) that: (1) acquaintance with a thing (a kind of knowledge) does not logically require knowledge of its relations; and (2) knowledge of some of a thing s relations does not necessarily include knowledge of all of its relations nor a knowledge of all the truths about the thing. Here, Russell gives the following example: I may be acquainted... with my toothache, and this knowledge may be as complete as knowledge by acquaintance ever can be, without knowing all that the dentist (who is not acquainted with it) can tell me about its cause, and without therefore knowing its nature in... [Hegel s] sense ( ). Russell concludes that the fact that a thing has relations to other things does not prove that these relations are logically necessary. That is, we cannot validly deduce a thing s relations to other things from the thing s nature. For something we are acquainted with, we can be misled into thinking that its relations to other things are necessary they seem necessary because we know the thing already. Russell s conclusion: It follows that Hegel cannot prove that the universe as a whole forms a single harmonious system, nor can he prove that space, time, matter, and evil are unreal just because they are fragmentary and relational. For Russell, we cannot figure out the nature of reality through pure reasoning. We must investigate the world on a piecemeal basis, empirically and scientifically. We cannot know those aspects of reality that are beyond our experience. Criticism of Traditional Philosophical Attempts to Deny Apparent Features of the World In this section, Russell defends an empirical and scientific approach to reality against the attempts of traditional metaphysicians to show through abstract reasoning that certain apparent features of the actual world cannot, in fact, be real. 12

13 Example: the infinite extent and infinite divisibility of space and time. Russell points out that space and time appear to be infinite in extent and infinitely divisible (see p. 146). He then states that philosophers [he does not name names here] have denied the infinite extent and infinite divisibility of space and time on the ground that there can be no infinite collections of things which led them further to the conclusion that space and time are finite, that they are neither infinite in extent nor infinitely divisible. Such philosophers claimed that there is a contradiction between, on the one hand, the way space and time appear, which requires the reality of infinite collections, and, on the other hand, the impossibility of infinite collections, which these philosophers believed they had proved. According to Russell, it was Immanuel Kant ( ) who first emphasized this contradiction, deduced the impossibility of space and time, which he declared to be merely subjective.... Following Kant, many philosophers (according to Russell) have viewed space and time as mere appearances, not features of the world as it really is. [There were also philosophers before Kant who pointed out logical problems with the ideas of space and time, e.g., Zeno of Elea (5th century BC), David Hume ( ).] Russell claims that modern mathematicians, such as Georg Cantor ( ), have proved that the existence of infinite collections is possible (not impossible) and that therefore it is possible (not impossible) that space and time are, on the one hand, both infinite in extent and infinitely divisible and, on the other hand, real. [Russell does not explain just how the mathematicians have shown this.] In addition to this, the development (in the 19th century) of non-euclidean geometries shows that forms of space other than Euclidean [common sense] space are possible (see pp ). Russell then comments as follows: Thus the position is completely reversed. Formerly it appeared that experience left only one kind of space to logic, and logic showed this one kind to be impossible. Now logic presents many kinds of space as possible apart from experience, and experience only partially decides between them. Thus, while our knowledge of what is has become less than it was formerly supposed to be, our knowledge of what may be is enormously increased. Instead of being shut in within narrow walls, of which every nook and cranny could be explored, we find ourselves in an open world of free possibilities, where much remains unknown because there is so much to know. ( ) [emphasis added] 13

14 On the basis of his discussion of the space-and-time issue, Russell rejects traditional philosophical attempts to define what reality must be by means of a priori principles. Modern philosophy, logic, mathematics, and science now present us with many alternative realities (which transcend unreflective common sense ). Where possible, we must now decide on the basis of experience which of the many worlds presented to us we will accept as real [for various purposes?]. Knowledge of what exists is limited to what we can learn from experience.... (148) The Roles of the Empirical and the A Priori in the Acquisition of Knowledge Russell does not believe that all of our knowledge derives from actual perceptual experience. He says that we have knowledge concerning things of which we have no direct experience (280). There is a conceptual (a priori) element in our knowledge, namely, our use of universals (general concepts such as blue, three, humanity, etc.). This conceptual aspect of our mental equipment enables us to draw inferences from experience that take us beyond experience. Russell s example here is that we are able to infer the existence of physical objects from our sensations on the basis of the a priori principle that sense-data are signs of physical objects. According to Russell, it is only in virtue of this principle that experience enables us to acquire knowledge concerning physical objects. Russell continues, arguing that our intuitive (non-inferential) knowledge, which is the source of all our other knowledge of truths, is of two sorts: 1. pure empirical knowledge, which tells us of the existence and some of the properties of particular things with which we are acquainted, and 2. pure a priori knowledge, which gives us connections between universals, and enables us to draw inferences from the particular facts given in empirical knowledge. Our derivative (inferential) knowledge always depends upon some pure a priori knowledge and usually also depends upon some pure empirical knowledge. Philosophy as the Criticism of Knowledge Claims Philosophy as criticism: Philosophy is the critical examination of the principles employed in science and in daily life; it searches out any inconsistencies there may be in these principles, and it only accepts them when, as the result of a critical inquiry, no reason for rejecting them has appeared ( ). On this basis, the grand theories of traditional metaphysicians do not seem persuasive. But as regards what would be commonly accepted as knowledge, our result is in the main positive: we have seldom found reason to reject such knowledge as the result of our criticism, and we have seen no reason to suppose 14

15 man incapable of the kind of knowledge which he is generally believed to possess (150). The essence of philosophy: Descartes methodical doubt, not absolute skepticism According to Russell, philosophy as a criticism of knowledge claims should not end in complete (absolute) skepticism because complete skepticism is unreasonable. Russell praises Descartes methodical doubt and says that it is the essence of philosophy. Descartes proceeded by doubting whatever seemed doubtful and by considering each of his beliefs to determine whether he could know for certain that the belief was true. This, writes Russell, is the kind of criticism which constitutes philosophy (151). Some knowledge, such as knowledge of the existence of our sense-data [the colors, shapes, etc., that appear in our sensations], appears quite indubitable, however calmly and thoroughly we reflect upon it. In regard to such knowledge, philosophical criticism does not require that we should abstain from belief. But there are beliefs such, for example, as the belief that physical objects exactly resemble our sense-data which are entertained until we begin to reflect, but are found to melt away when subjected to a close inquiry. Such beliefs philosophy will bid us reject, unless some new line of argument is found to support them. (151) Absolute skepticism is unreasonable because it rejects beliefs that are not open to any objections, such as the belief that sense-data exist. Philosophy as criticism considers each piece of apparent knowledge on its merits, and retains whatever still appears to be knowledge when this consideration is completed (151). That some risk of error remains must be admitted, since human beings are fallible. Philosophy may claim justly that it diminishes the risk of error, and that in some cases it renders the risk so small as to be practically negligible. To do more than this is not possible in a world where mistakes must occur; and more than this no prudent advocate of philosophy would claim to have performed. ( ) 15