There are many statements that make no sense in their entirety but contain enough conjuncts to appear intelligible to a reader. For example, consider this statement:
“Tony Blair’s first movie appearance was in Full Metal Jacket.”
The statement is false in a number of ways – namely
that Tony Blair never appeared in movies, so wasn’t in Full Metal Jacket. But
it is a coherent statement in that one could assess its veracity based on the
information contained.
Now consider another statement:
“The dog on Westminster
Bridge is fed up with all
these terrorist attacks.”
This statement is less coherent because we don’t
really know what it means for dogs to be fed up, let alone fed up with human
things like terrorism. As Bertrand Russell said, a statement can be true only
if none of its propositions are false. It could be true that there is a dog on Westminster Bridge ; and it could be true that people
are fed up with terrorist attacks; and it is true that there is someone called
Tony Blair; and it is true that there is a movie called Full Metal Jacket - but when
expressed as a conjunction of claims, neither statement is true.
My perception of language
paradoxes is that they belong in the same family as the conjunction problems above: they are rather like
linguistic versions of Escher drawings. Paradoxes are about a limitation in
defining a perception or definition of a statement. Either the language
employed is not precise enough to encapsulate that which is being described, or
we are attempting to define something and getting our first and second order
terms mixed up.
The liar paradox is a
famous statement that seems to present a problem. The statement 'This sentence
is false' has the paradox: if it's true then it's false, and if it's false then
it's true. Mathematician Alfred Tarski sought to resolve the dilemma by talking about levels of
language and how they predicate truth or falsehood. When one sentence refers to
the truth or falsehood of another sentence, then according to Tarski it is
'semantically higher'. If I said "It rained on Westminster Bridge
at mid-day on March 23rd 2014" and called that statement Statement 1, then
there is a higher level proposition attached to it "Statement 1 is
False". Here the truth or falsity of the proposition clearly is predicated
on whether there was rainfall on Westminster
Bridge at mid-day on
March 23rd 2014.
But when it comes to
statements like 'This sentence is false', while the language employed makes
sense on a word-by-word basis, the level at which it is employed doesn't,
because it is stated as a higher level statement, when in fact it isn't about
anything related to a lower level proposition. Because of this we can construct
sentences that accord with our ordinary semantic rules, but they cannot
consistently be assigned a truth value because they are in isolation from a
concomitant statement.
Statement A: “Every even
number is the sum of two prime numbers"
Statement B: “The
statement that every even number is the sum of two prime numbers cannot be
proven.”
Either
Statements A and B are both true or they are both false. If they are both true
then there is a statement in arithmetic that cannot be proven. And if they are
both false then we have proof that we can prove a false statement. If upon
reading the statement 'This sentence is false" you decide to say that it
is neither true nor false, you come smack up against the Godelian problem that
there is no complete system of rules of inference in mechanised logic, and that
any formally mechanised system in which a categorical set of axioms exists
cannot be captured in one grand slam rationale without leaving a brute residue
of incompleteness. But if on the other hand upon reading the statement "Every
even number is the sum of two prime numbers” you decide to say that it's
neither true nor false you find this cannot be allowed because it must be
either true or false.
Another
one: here’s one of Zeno’s famous paradoxes; If I fire an arrow directly at you,
the arrow will never reach you. Suppose the distance the arrow travels is 10
metres – Zeno shows how it will never reach its target, because it first has to
travel half that distance (1/2), then half again (1/4), and then half again (1/8),
an so on, ad infinitum. Zeno’s ‘logic’ told him that the arrow would carry on
travelling indefinitely, but his senses told him that it would reach its
target. Then it was later shown
(principally by Leibniz) that this sequence of common ratios (1/2,1/4,1/8,1/16,
etc) converges into 1 as a geometric series. Despite Zeno’s logic of infinite
travelling, the mathematics supports what Zeno’s senses showed, even if
physical reality does not, as King Harold would attest.
Logical
paradoxes can give the impression of an illogical world – but as Wittgenstein
said in his Tractatus, we could not
say what an illogical world would look like. It is because language is a human
construction that we get into these semantic situations. The statement ‘I am lying’ which as we've said, is
false if it’s true and true if it’s false - but why this paradox occurs should
be easily seen when we treat language as a mere invention with first-order,
second-order (and so on) statements.
Clearly to avoid self-contradiction, ‘I am lying’ has to be a statement that
refers to a statement other than the one being made. If John is lying about
where he was last night, then the statement John makes which says “I was round
Terry’s last night” needs to be related to the second order statement about the
first-order perspective, which is “It is true that I, John, was round Terry’s
last night”, which is a statement about a statement. The second order statement
is a statement about the first order statement, and here John can be lying by
relating his whereabouts to the truth or falsity of his whereabouts – but with
‘I am lying’ he would be mistakenly conflating first and second order
statements without the other level with which to correlate the ‘lie’ in
question.
Locke, in his Essay Concerning
Human Understanding, talked about the vitalness of language in that it maps
words to ideas, concepts or representations in each person's mind. This is one
of the principal reasons why humans are the most advanced of all the animals;
the ability for one man to share the concepts in his head with the concepts in someone
else's head by some form of mutual consent is a key foundation in our being
able to construct moral systems, as well as build skyscrapers and jumbo jets. To
conjoin private concepts to a word, sentence or paragraph in our common
language is to take us one huge step forward in realising the potential of our
minds in a shared human reality. To that end, language paradoxes represent us
at our most brilliant and at our most frivolous simultaneously.