Prof. Norman Swartz, Copyright © 1997.
http://www.sfu.ca/~swartz/knowledge2.htm
October 10, 1997
Department of Philosophy
Simon Fraser University

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Lecture Notes on Knowledge
Part Two

 

Contents




 

Is knowledge of the future possible?

Skeptic: It is impossible to know the future. We may believe we know, but something 'could go wrong' between now and the predicted event. Thus knowledge of the future is impossible.

Reply 1:

Knowing P does not require that there be no possibility of our making a error. Yes, we could make a mistake, yes, something might happen that will make our prediction turn out false, but that is no reason to claim that we cannot know the future. What is required is that we have good grounds to make our prediction and that they be true, not that there be no possibility of error.

Consider this case.
Imagine a piano competition in which ten outstanding young Canadian pianists have worked their way up to the finals. In turn, they each perform some exceedingly difficult pieces before a panel of seven judges. After all competitors have performed, the judges move into a closed room to reach their decision.

There is a unanimous decision that one particular pianist, Helene de Beauvoir, performed head and shoulders above the other nine. Indeed there is a unanimous opinion that her performance was perfect. She never made an error.

But then something strange happened. When the vote was taken to award her first prize, one judge voted against awarding her first prize. When the other (flabbergasted) judges asked him why, he replied: "Yes, her performance was perfect, but she could have made a mistake." When the other judges protested: "Of course she could have made a mistake (anybody could); but she didn't and it is the fact that she didn't, that counts; not the fact that she could have." But the dissenting judge is adamant. "Nope: that she performed perfectly isn't good enough; I require not only that she perform perfectly, but that she couldn't have made a mistake." The other judges shook their heads. Helene, who received six votes (out of a possible seven) was awarded first prize.


Reply 2:

One must be careful not to set the requirements, for knowing the future, unrealistically high. For such standards can rebound and make it impossible to know the past as well.

Suppose one has good evidence that something will happen tomorrow (e.g. that there will be a high tide at Spanish Banks sometime during that 24-hour period) or even further in the future (e.g. that there will be a US Presidential election in 2000 AD). The evidence for these future events is better than the evidence of a great many past events that we are convinced we know. Memory, we have learned, is not as reliable as we had believed. (See the discussion in the textbook pp. 62-64).

Understand that I am not being especially skeptical about the past. All I am trying to do is to draw a parallel between knowledge of the past and knowledge of the future. The parallels are these: in both sorts of cases it is possible to have very strong evidence; in both sorts of cases it is possible to be mistaken. Possibly being mistaken is not a condition unique to claims about knowing the future; it applies equally to claims about knowing the past.


 

Strong sense of "knows" and weak sense of "knows"

On pp. 48-50, Hospers introduces and discusses a distinction between what he calls "the strong sense of 'knows'" and "the weak sense of 'knows'". He says that the weak sense is the 'ordinary' sense, and that the strong sense is a 'philosophically stringent sense' (bottom of page 49).

As Hospers explicates the concept, the strong sense of "knows" requires conclusive evidence that P. (Understand that Hospers is merely reporting the ideas of some other philosophers. I do not believe that Hospers, himself, adopts this strong sense.)

Let's back up a bit. It is useful to remind ourselves of the standard analysis, namely:

    x knows that P only if

      1.  x believes (on the basis of e) that P
      2.  P (is true)
      3.  x has good evidence e (or reason) to believe that P.
Now, suppose one were to adopt the so-called strong sense of "knows". What would the analysis become? Presumably this:

    x knows that P only if

      1.  x believes (on the basis of e) that P
      2.  P (is true)
      3'. x has conclusive evidence e (or reason) to believe that P.
Note that the only difference in the statements of these two analyses lies in substituting "conclusive" (in 3') for "good" (in 3).

But there is something peculiar about the latter analysis. It contains a redundant (or superfluous) condition.

If the evidence, e, is conclusive, i.e. if it guarantees the truth of P, then there is no reason to have condition #2 (i.e. P [is true]) as a separate condition. That second condition (viz. that P is true) will be guaranteed on the strength of condition 3'.

So, the person who argues for, and adopts, the strong sense of "knows" is, in effect, arguing for a different analysis:

    x knows that P only if

      1.  x believes (on the basis of e) that P
      2.  [deleted – since superfluous]
      3'. x has conclusive evidence e (or reason) to believe that P.
My own view is that a person who argues for the 'strong' sense of "knows" has overlooked the role of the truth-condition. He/she wants to cater for the case where a person might be mistaken in claiming to know something. But it is not necessary to require conclusive evidence to cater for the possibility of error. The possibility of error is already 'looked after' by the truth-condition in the standard account: if a person has good evidence for believing that P, but if the evidence is incomplete and P is actually false, then – by condition #2 on the standard account – that person does not know P.


 

"Knows" and "knows for certain"

CASE 1: "Some" does not mean (i.e. is not a synonym for) "some but not all".
An illustration –

A new family moves to a home on my street and my neighbor, who has not met any of them, asks me, "Do they have any daughters?" I reply, "I don't know. I have seen some children playing there, and they were boys."

My answer "some" does not imply that I have not seen all. It is left as an open question whether I have seen only some (i.e. some but not all) or whether, in having seen some, I have in fact seen all.
CASE 2: "Belief" does not mean (i.e. is not a synonym for) "religious belief".

CASE 3: "Priest" does not mean (i.e. is not a synonym for) "Catholic priest".

CASE 4: "Transgression" does not mean (i.e. is not a synonym for) "moral transgression".

Finally, and this is the point of invoking the four previous examples,

CASE 5: "Knows" does not mean (i.e. is not a synonym for) "knows for certain".

A number of philosophers have argued that unless one 'knows for certain' one does not know at all. This claim would be true only if "knows" and "knows for certain" were synonyms, or if "for certain" were redundant when applied to "knows" (as would be "four-sided" when applied to "square").

To adopt the claim that one knows (that P) only when one knows for certain (that P), leads immediately to a variety of skepticisms. I can see no good reason to adopt such a view. My own attitude is that philosophy should sharpen concepts, make them more useful, and should not distort them beyond all recognition and use.


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