reasoning methods which seemingly cannot be "encapsulated"-they resist
being incorporated into any formal system. Thus, at first sight, it seems that
G6del has unearthed a hitherto unknown, but deeply significant, differ-
ence between human reasoning and mechanical reasoning. This mysteri-
ous discrepancy in the power of living and nonliving systems is mirrored in
the discrepancy between the notion of truth, and that of theoremhood ...
or at least that is a "romantic" way to view the situation.The Modified pq-System and Inconsistency
In order to see the situation more realistically, it is necessary to see in more
depth why and how meaning is mediated, in formal systems, by isomor-
phisms. And I believe that this leads to a more romantic way to view the
situation. So we now will proceed to investigate some further aspects of the
relation between meaning and form. Our first step is to make a new formal
system by modifying our old friend, the pq-system, very slightly. We add
one more axiom schema (retaining the original one, as well as the single
rule of inference):AXIOM SCHEMA II: If x is a hyphen-string, then xp-qx is an axiom.
Clearly, then, --p-q--is a theorem in the new system, and so is
--p--q---. And yet, their interpretations are, respectively, "2 plus 1
equals 2", and "2 plus 2 equals 3". It can be seen that our new system will
contain a lot of false statements (if you consider strings to be statements).
Thus, our new system is inconsistent with the external world.
As if this weren't bad enough, we also have internal problems with our
new system, since it contains statements which disagree with one another,
such as -p-q--(an old axiom) and -p-q-(a new axiom). So our system
is inconsistent in a second sense: internally.
Would, therefore, the only reasonable thing to do at this point be to
drop the new system entirely? Hardly. I have deliberately presented these
"inconsistencies" in a wool-pulling manner: that is, I have tried to present
fuzzy-headed arguments as strongly as possible, with the purpose of mis-
leading. In fact, you may well have detected the fallacies in what I have
said. The crucial fallacy came when I unquestioningly adopted the very
same interpreting words for the new system as I had for the old one.
Remember that there was only one reason for adopting those words in the
last Chapter, and that reason was that the symbols acted isomorphically to the
concepts which they wen~ matched with, by the interpretation. But when you
modify the rules governing the system, you are bound to damage the
isomorphism. It just cannot be helped. Thus all the problems which were
lamented over in preceding paragraphs were bogus problems; they can be
made to vanish in no time, by suitably reinterpreting some of the symbols of the
system. Notice that I said "some"; not necessarily all symbols will have to be
mapped onto new notions. Some may very well retain their "meanings",
while others change.Consistency, Completeness, and Geometry^87