A.J. Ayer, Knowing as Having the Right to be Sure

The answers which we have found for the questions we have so far been discussing have not yet put us in a position to give a complete account of what it is to know that something is the case. The first requirement is that what is known should be true, but this is not sufficient; not even if we add to it the further condition that one must be completely sure of what one knows. For it is possible to be completely sure of something which is in fact true, but yet not to know it. The circumstances may be such that one is not entitled to be sure. For instance, a superstitious person who had inadvertently walked under a ladder might be convinced as a result that he was about to suffer some misfortune; and he might in fact be right. But it would not be correct to say that he knew that this was going to be so. He arrived at his belief by a process of reasoning which would not be generally reliable; so, although his prediction came true, it was not a case of knowledge. Again, if someone were fully persuaded of a mathematical proposition by a proof which could be shown to be invalid, he would not, without further evidence, be said to know the proposition, even though it was true. But while it is not hard to find examples of true and fully confident beliefs which in some ways fail to meet the standards required for knowledge, it is not at all easy to determine exactly what these standards are.

One way of trying to discover them would be to consider what would count as satisfactory answers to the question How do you know? Thus people may be credited with knowing truths of mathematics or logic if they are able to give a valid proof of them, or even if, without themselves being able to set out such a proof, they have obtained this information from someone who can. Claims to know empirical statements may be upheld by a reference to perception, or to memory, or to testimony, or to historical records, or to scientific laws. But such backing is not always strong enough for knowledge. Whether it is so or not depends upon the circumstances of the particular case. If I were asked how I knew that a physical object of a certain sort was in such and such a place, it would, in general, be a sufficient answer for me to say that I could see it; but if my eyesight were bad and the light were dim, this answer might not be sufficient. Even though I was right, it might still be said that I did not really know that the object was there. If I have a poor memory and the event which I claim to

A.J. Ayer, Knowing as Having the Right to be Sure, The Froblem o f Knowledge (London: Macmillan, 1956).

440

GuidoResaltado

GuidoNota adhesiva 1. Primer y segundo requerimiento: (i) P (lo que se conoce) es verdadero) y (ii) S est seguro que P es verdadero.Ms adelante, Ayer sostendr que (i) y (ii) son necesarias, pero no suficientes

KNOWING AS HAVING THE RIGHT TO BE SURE

remember is remote, my memory of it may still not amount to knowledge, even though in this instance it does not fail me. If a witness is unreliable, his unsupported evidence may not enable us to know that what he says is true, even in a case where we completely trust him and he is not in fact deceiving us. In a given instance it is possible to decide whether the backing is strong enough to justify a claim to knowledge. But to say in general how strong it has to be would require our drawing up a list of the conditions under which perception, or memory, or testimony, or other forms of evidence are reliable. And this would be a very complicated matter, if indeed it could be done at all.

Moreover, we cannot assume that, even in particular instances, an answer to the question How do you know? will always be forthcoming. There may very well be cases in which one knows that something is so without its being possible to say how one knows it. I am not so much thinking now of claims to know facts of immediate experience, statements like I know that I feel pain, which raise problems of their own. In cases of this sort it may be argued that the question how one knows does not arise. But even when it clearly does arise, it may not find an answer. Suppose that someone were consistently successful in predicting events of a certain kind, events, let us say, which are not ordinarily thought to be predictable, like the results of a lottery. If his run of successes were sufficiently impressive, we might very well come to say that he knew which number would win, even though he did not reach this conclusion by any rational method, or indeed by any method at all. We might say that he knew it by intuition, but this would be to assert no more than that he did know it but that we could not say how. In the same way, if someone were consistently successful in reading the minds of others without having any of the usual sort of evidence, we might say that he knew these things telepathically. But in default of any further explanation this would come down to saying merely that he did know them, but not by any ordinary means. Words like intuition and telepathy are brought in just to disguise the fact that no explanation has been found.

But if we allow this sort of knowledge to be even theoretically possible, what becomes of the distinction between knowledge and true belief? How does our man who knows what the results of the lottery will be differ from one who only makes a series of lucky guesses? The answer is that, so far as the man himself is concerned, there need not be any difference. His procedure and his state of mind, when he is said to know what will happen, may be exactly the same as when it is said that he is only guessing. The difference is that to say that he knows is to concede to him the right to be sure, while to say that he is only guessing is to withhold it. Whether we make this concession will depend upon the view which we take of his performance. Normally we do not say that people know things unless they have followed one of the accredited routes to knowledge. If someone reaches a true conclusion without appearing to have any adequate basis for it, we are likely to say that he does not really know it. But if he were repeatedly successful in a given domain, we might very well come to say that he knew the facts in question, even though we could not explain how he knew them. We should grant him the right to be sure, simply on the basis of his success. This is, indeed, a point on which peoples views might be expected to differ. N ot everyone would regard a successful run of predictions, however long sustained, as being by itself a sufficient backing for a claim to knowledge. And here there can be no question of

441

GuidoResaltado2. Condicin (iii) S tiene el derecho a pensar que P es verdadera.

A .J. A YER

proving that this attitude is mistaken. Where there are recognized criteria for deciding when one has the right to be sure, anyone who insists that their being satisfied is still not enough for knowledge may be accused, for what the charge is worth, of misusing the verb to know. But it is possible to find, or at any rate to devise, examples which are not covered in this respect by any established rule of usage. Whether they are to count as instances of knowledge is then a question which we are left free to decide.

It does not, however, matter very greatly which decision we take. The main problem is to state and assess the grounds on which these claims to knowledge are made, to settle, as it were, the candidates marks. It is a relatively unimportant question what titles we then bestow upon them. So long as we agree about the marking, it is of no great consequence where we draw the line between pass and failure, or between the different levels of distinction. If we choose to set a very high standard, we may find ourselves committed to saying that some of what ordinarily passes for knowledge ought rather to be described as probable opinion. And some critics will then take us to task for flouting ordinary usage. But the question is purely one of terminology. It is to be decided, if at all, on grounds of practical convenience.

One must not confuse this case, where the markings are agreed upon, and what is in dispute is only the bestowal of honours, with the case where it is the markings themselves that are put in question. For this second case is philosophically important, in a way in which the other is not. The sceptic who asserts that we do not know all that we think we know, or even perhaps that we do not strictly know anything at all, is not suggesting that we are mistaken when we conclude that the recognized criteria for knowing have been satisfied. Nor is he primarily concerned with getting us to revise our usage of the verb to know, any more than one who challenges our standards of value is trying to make us revise our usage of the word good. The disagreement is about the application of the word, rather than its meaning. W hat the sceptic contends is that our markings are too high; that the grounds on which we are normally ready to concede the right to be sure are worth less than we think; he may even go so far as to say that they are not worth anything at all. The attack is directed, not against the way in which we apply our standards of proof, but against these standards themselves. It has, as we shall see, to be taken seriously because of the arguments by which it is supported.

I conclude then that the necessary and sufficient conditions for knowing that something is the case are first that what one is said to know be true, secondly that one be sure of it, and thirdly that one should have the right to be sure. This right may be earned in various ways; but even if one could give a complete description of them it would be a mistake to try to build it into the definition of knowledge, just as it would be a mistake to try to incorporate our actual standards of goodness into a definition of good. And this being so, it turns out that the questions which philosophers raise about the possibility of knowledge are not all to be settled by discovering what knowledge is. For many of them reappear as questions about the legitimacy of the title to be sure. They need to be severally examined; and this is the main concern of what is called the theory of knowledge.

442

GuidoResaltado5. Sntesis.

GuidoResaltado3. No obstante, La condicin (iii) parece ser problemtica ya que hay muchas maneras en que S puede argir que tiene el derecho a saber que P.

GuidoResaltado4. A pesar de que puede haber disputas en torna al modo de 'tener el derecho a saber que P es verdadera' (marking), lo que no es objeto de disputa es que la condicin (iii) debe ser satisfecha.

KNOWING AS HAVING THE RIGHT TO BE SURE

Q UESTIONS

1 According to Ayer, what three conditions are required in order for a person, S, to know a proposition, p?

2 According to Ayer, what do philosophical skeptics believe? Do they seek to change our use of the word know?

443

Edmund Gettier, Is Justified True Belief Knowledge?

Various attempts have been made in recent years to state necessary and sufficient conditions for someones knowing a given proposition. The attempts have often been such that they can be stated in a form similar to the following.1

(a) S knows that P IFF (i) P is true,(ii) S believes that P, and

(iii) S is justified in believing that P.For example, Chisholm has held that the following gives the necessary and sufficient conditions for knowledge:2

(b) S knows that P IFF (i) S accepts P,(ii) S has adequate evidence for P,

and(iii) P is true.

Ayer has stated the necessary and sufficient conditions for knowledge as follows:3

(c) S knows that P IFF (i) P is true,(ii) S is sure that P is true, and

(iii) S has the right to be sure that Pis true.

I shall argue that (a) is false in that the conditions stated therein do not constitute a su fficient condition for the truth of the proposition that S knows that P. The same argument will show that (b) and (c) fail if has adequate evidence for or has the right to be sure that is substituted for is justified in believing that throughout.

I shall begin by noting two points. First, in that sense of justified in which Ss being justified in believing P is a necessary condition of Ss knowing that P, it is possible for a person to be justified in believing a proposition that is in fact false. Secondly, for any proposition P, if S is justified in believing P, and P entails Q, and S deduces Q from P and accepts Q as a result of this deduction, then S is justified in believing Q. Keeping these two points in mind, I shall now present two cases in which the conditions stated in (a) are true for some proposition,

Edmund Gettier, Is Justified True Belief Knowledge? Analysis 23 (1963): 121-3.

444

GuidoResaltado1. Objetivo del artculo.

GuidoResaltado2. Importante. Este es la primer Supesto adicional que debe asumirse para que el anlisis de Gettier logre el objetivo sealado en la nota anterior: El sentido en que se toma 'justificado' en 'S est justificado en creer P' como condicin necesaria de 'S conoce o sabe que P', deja abierta la posibilidad de que una persona est justificada en creer una proposicin que es de hecho falsa. (Esta traduccin no es literal, sino que est pedaggicamente modificada.) En las notas que siguen me referir a este supuesto como SA1

GuidoResaltado3. Segundo Supuesto adicional: Para cualquier proposicin P, (i) si S est justificado en creer que P, y (ii) P entraa Q, y (iii) S deduce Q a partir de P y(iv) S acepta Q como resultado de esta deduccin

Entonces, S est justificado en creer que P.

Esta premisa es crucial para entender el argumento de Gettier. Se sealar en las notas como 'SA2'

IS JU S T IF IE D T R U E B E L IE F K N O W L E D G E ?

though it is at the same time false that the person in question knows that proposition.

Case I

Suppose that Smith and Jones have applied for a certain job. And suppose that Smith has strong evidence for the following conjunctive proposition:

(d) Jones is the man who will get the job, and Jones has ten coins in his pocket.

Smiths evidence for (d) might be that the president of the company assured him that Jones would in the end be selected, and that he, Smith, had counted the coins in Joness pocket ten minutes ago. Proposition (d) entails:

(e) The man who will get the job has ten coins in his pocket.

Let us suppose that Smith sees the entailment from (d) to (e), and accepts (e) on the grounds of (d), for which he has strong evidence. In this case, Smith is clearly justified in believing that (e) is true.

But imagine, further, that unknown to Smith, he himself, not Jones, will get the job. And, also, unknown to Smith, he himself has ten coins in his pocket. Proposition (e) is then true, though proposition (d), from which Smith inferred (e), is false. In our example, then, all of the following are true: (i) (e) is true, (ii) Smith believes that (e) is true, and (iii) Smith is justified in believing that (e) is true. But it is equally clear that Smith does not k n o w that (e) is true; for (e) is true in virtue of the number of coins in Smiths pocket, while Smith does not know how many coins are in Smiths pocket, and bases his belief in (e) on a count of the coins in Joness pocket, whom he falsely believes to be the man who will get the job.

Case II

Let us suppose that Smith has strong evidence for the following proposition:

(f) Jones owns a Ford.

Smiths evidence might be that Jones has at all times in the past within Smiths memory owned a car, and always a Ford, and that Jones has just offered Smith a ride while driving a Ford. Let us imagine, now, that Smith has another friend, Brown, of whose whereabouts he is totally ignorant. Smith selects three place- names quite at random, and constructs the following three propositions:

(g) Either Jones owns a Ford, or Brown is in Boston;(h) Either Jones owns a Ford, or Brown is in Barcelona;(i) Either Jones owns a Ford, or Brown is in Brest-Litovsk.

Each of these propositions is entailed by (f). Imagine that Smith realizes the entailment of each of these propositions he has constructed by (f), and proceeds

445

GuidoResaltadoNtese que en la situacin que describe Gettier, Smith solamente tiene evidencia fuerte para (d). De esto podra inferirse que Smith est justificado en creer que Jones es el hombre que obtendr el trabajo y Jones tiene diez monedas en el bolsillo. Por lo tanto, esto podra corresponder a 'S est justificado en creer que P' (a(iii)). No obstante, puesto que, posteriormente Smith infiere vlidamente (por SA2) (e), estar justificado en creer que (e).

GuidoResaltado6. Esto corresponde a la posibilidad expresada en SA1. Pese a que Smith est justificado en creer (d), dicha proposicin es falsa. No obstante la verdad de (e) se preserva, ya que de hecho es verdadera, aunque Smith no sepa (o conozca) que lo es.

GuidoResaltado7.Nuevamente, Smith tiene fuerte evidencia para esta proposicin y, por lo tanto, estara justificado en creer (f).

GuidoResaltado5. La seleccin al azar de las tres proposiciones que involucran a Jones y a Brown (del cual Smith poco sabe en ese momento), se justifica porque (g), (h) e (i) contiene dos proposiciones ligadas por una disyuncin. Dado que Smith tiene fuerte evidencia o est justificado para creer que Jones posee un Ford, que es una de las proposiciones que compone las disyunciones (g), (h) e (i) y dado que para ser verdadera una disyuncin solamente requiere que una de las proposiciones que la componen sea verdadera, la inferencia (por AS2) desde (f) a (g), (h) e (i) es vlida, aun cuando Smith haya seleccionado esas proposiciones al azar.

GuidoNote4. Ntese que en la situacin que describe Gettier, Smith solamente tiene evidencia fuerte para (d). De esto podra inferirse que Smith est justificado en creer que Jones es el hombre que obtendr el trabajo y Jones tiene diez monedas en el bolsillo. Por lo tanto, esto podra corresponder a 'S est justificado en creer que P' (iii)). No obstante, puesto que, posteriormente Smith infiere vlidamente (por SA2) (e), estar justificado en creer que (e).

GuidoNote5. Esto se infiere por SA2. Vase la aclaracin en el prrafo que sigue en el texto de Gettier. Como (e) satisface SA2, (e) es la proposicin que Smith sabe.

GuidoNote8. La seleccin al azar de las tres proposiciones que involucran a Jones y a Brown (del cual Smith poco sabe en ese momento), se justifica porque (g), (h) e (i) contiene dos proposiciones ligadas por una disyuncin. Dado que Smith tiene fuerte evidencia o est justificado para creer que Jones posee un Ford, que es una de las proposiciones que compone las disyunciones (g), (h) e (i) y dado que para ser verdadera una disyuncin solamente requiere que una de las proposiciones que la componen sea verdadera, la inferencia (por AS2) desde (f) a (g), (h) e (i) es vlida, aun cuando Smith haya seleccionada esas proposiciones al azar.

ED M U N D G E T T IE R

to accept (g), (h), and (i) on the basis of (f). Smith has correctly inferred (g), (h), and (i) from a proposition for which he has strong evidence. Smith is therefore completely justified in believing each of these three propositions. Smith, of course, has no idea where Brown is.

But imagine now that two further conditions hold. First, Jones does n ot own a Ford, but is at present driving a rented car. And secondly, by the sheerest coincidence, and entirely unknown to Smith, the place mentioned in proposition (h) happens really to be the place where Brown is. If these two conditions hold then Smith does n ot know that (h) is true, even though (i) (h) is true, (ii) Smith does believe that (h) is true, and (iii) Smith is justified in believing that (h) is true.

These two examples show that definition (a) does not state a sufficient condition for someones knowing a given proposition. The same cases, with appropriate changes, will suffice to show that neither definition (b) nor definition (c) do so either.

Notes

1 Plato seem s to be considering some such definition at Theaetetus 201 , and perhaps accepting one at Meno 98.

2 Roderick M. Chisholm, Perceiving: a Philosophical Study (Ithaca, N.Y.: Cornell University Press, 1957), p. 16.

3 A.J. Ayer, The Problem o f Knowledge (London: Macmillan, 1956), p. 34.

QUESTIONS

1 According to Gettier, is justified true belief knowledge?2 What two points about justification does Gettiers argument rely on?3 In Gettiers two examples, what true propositions did Smith not know?

446

GuidoResaltado9. Al igual que en el caso anterior, aunque Smith est justificado en creer (f), sta resulta ser falsa. Si lo es, entonces (g), (h) e (i), tambin lo seran. A pesar de que la inferencia de las disyunciones a partir de (f) contina siendo vlida, no satisface SA2. Si no satisface SA2, entonces el anlisis de Gettier no satisface una de sus condicones de adecuacin. Pero ...

GuidoResaltado10. Pero, resulta que, sin que Smith lo sepa, Brown est en Barcelona. Esto hace que la disyuncin (h) sea verdadera. De este modo,el anlisis es adecuado, ya que preserva SA1 y SA2.

Este es un caso de aquello que los epistemlogos denominan 'suerte epistmica'.