| Knows: A person a
knows that q iff (a believes q) and (q).
Note that this is meant in the sense: a
has a belief to the effect that q, and as a matter of fact q is true,
regardless of a's reasons for believing in q, and also regardless of
whether or not it is in fact widely known that q is true.
1. As defined, knows is
propositional attitude defined in terms of
believes, and things are intentionally left simple.
One common widely accepted definition of
is "justified true belief", but there are several problems with the
"justified" part, that is left out above.
One reason is that one may
be justified in quite a good sense yet be mistaken, as happens in
science, and as may happen to oneself if one believes one's car
keys are in the trash-can because one's little daughter has put them
there, whereas they are there but for another reason, and a third is
that the whole notion of justifying a belief is none too clear.
2. A complication of the above,
that is in fact quite welcome for many ends, is that (q) itself may be
a proposition that attributes some sort of
probability, as in "a knows that this fair coin has a probability
of falling heads of 1/2".
This is a complication because it makes
the analysis of what is involved in knowing more complicated, but it is
welcome because the analysis is more subtle and anyway all thinking
human beings believe in many probabilistic propositions.
3. It is quite consistent with
the given definition that a sincerely believes that a knows q, and that
a is completely mistaken - that is, a is right in maintaining (a
believes q) but as a matter of fact (~q). In brief, one may believe one
knows and be mistaken.
Indeed, since it seems quite true of
everyone that one knows about some of one's earlier beliefs that they
turned out to be mistaken, it follows that everyone knows
something, if only about one's own beliefs, one's own lack of
knowledge, or one's knowing the natural language with which one can
state claims to the effect that one knows almost nothing and
knows one knows this.
Now the proposed minimalistic definition
of knows is interesting also in that it is a conjunction of a
propositional attitude of a person (a
belief) and a statement of fact - while it would seem as if
the latter, even if true, cannot be known by the person except in the
form of a propositional attitude.
For the reasons just given it seems
quite sensible to assume that every living person knows something, if
only that one is often mistaken about what one believes one knows. That
is formally: (a)(Eq)(aKq), where "K" is short for "knows".
And this again is quite compatible in
principle with knowing one knows some things without knowing which,
except for this, or - far more realistically - with knowing that one
probably knows some things and certainly is mistaken about others,
without presently knowing which.
Incidentally, in these formulations a
non-constructive use is made of the
existential quantifier: If one knows one is mistaken about some
things and doesn't know which, one cannot instantiate them other than
by artiticial formulas like "Let t* be something I believe I know but
am mistaken about while I don't know more about it". (The tip of the
tongue phenomenon - "There is a name for this thing, I know, but I just
now can't recall it" - is another example of such an existential
4. There is a tradition that
adds to the given definition a clause
to an effect like this "(a has justifiable reasons
for believing q)". This
has been defended by
Ayer, after Ramsey have his version "(a found q by a reliable process",
and attacked by Gettier, who showed
that for many
examples may be thought of that made
the reasons both plausible
and mistaken - making the knower believe something that was true and that
he justifiably believed
himself to have good reasons to believe, except the knower was mistaken about his reasons.
t seems: Many have drawn
such as that the analysis
as "justified true belief" has
been overthrown or shown to be mistaken. All that has
been shown, it seems to me, is that one's
reasons for believing one knows may not be as good as one believes, and one may believe one knows, and indeed does know, but not for the reasons one believes it.
This is in line
with what is a more serious difficulty
with the concept of knowledge:
5. Much of what a person, or indeed what human
beings, once believed he knew, or they knew, perhaps also for what they
all thought were very good reasons, and indeed may have been
so, has been shown to be false.
One example is Newton's theory of
space, time and gravity, that was overthrown or at least
corrected by Einstein's theory of general relativity.
And this in turn may be found
to have been mistaken,
even though presently it counts as very
There are various ways
to deal with the problem that what seems firm and
justified knowledge may - perhaps long after
one has died - turn out to have been mistaken.
Since there are many kinds of knowledge
kinds of justifications of knowledge, probably the best
answer to this problem is to admit it for the case of scientific
knowledge, and therefore also
for any other kind of knowledge, on the ground
that scientific knowledge has the best justifications compared to other justifications, and to hold on to five
- First, any
knowledge that has been used for
manufacturing artefacts - cars, lamps, dynamos, bridges, airplanes,
computers - that did not exist without
it, must have gotten most things right even if some things may, after all, be found to be mistaken or not quite
correct. See adequacy.
makes sense to keep two general qualifications
(1) Even the best laid foundatiions of some specific claim to knowledge
may be mistaken
(2) Generally, mistakes in scientific knowledge that
technologically worked were
partial and local.
- Third, in
many ways, human knowledge has been accumulative: Newer knowledge generally
built on and arose from older knowledge, which it
often did not so much overthrow, though this happened too, as corrected in
some detail, and extended in a
hitherto unknownn direction.
one may be
mistaken in many details and convictions about facts, and while
one is always ignorant of much that will be known
eventually, if mankind keeps existing, thinking
and doing real science, it is unlikely
that a person with a scientific outlook,
and good knowledge of mathematics, logic, physics, biology, and history, is mistaken in
all major ways: This
has never happened to such persons (with a scientific outlook, and good
knowledge of with
scientific outlook, and good knowledge of
mathematics and science).
to get overthrown radically, in
nominally scientific traditions, which
are the only ones to take rationally serious in this
context of "justified true belief",
are for the most part specific
theories, that specify specific things, such as Priestly's phlogiston
(that was a mistaken theory about what is now called oxygen), and sometimes branches of some science, either because
they did involve assumptions of things shown to fail to
exist in fact, or else because their got to be better ways
to do that branch of science.
Finally, those who desire logical reasons
should consider that there is much any adult person
knows, in terms of mere natural language
and some basic mathematics and logic: One cannot even say cogently that "one
knows one does not know anything", for the least one needs to know to claim that, are the rules and terms of the natural language that one
states this incoherent