@ughaibu,
ughaibu wrote:
TuringEquivalent wrote:A repeated application of a rule don` t seem to imply that rule. Given that sequence " 2, 4, 6, 8...." it is easily to suppose the rule is 2*x, but it could also be something else.
I dont see a real problem. In the application of a rule, the rule is decided by the applier, that one cant be inductively certain of what, if any, rule has been applied, unless it was applied by oneself, is a separate issue.
TuringEquivalent wrote:My point is that rules don ` t seem to capture semantics.
I'm not sure how this follows. Aren't semantics a matter of agreement?
Well, the technical usage of meaning is really semantics.
Of course, we all agree that meaning of the symbol '0' is zero. The concept 'zero' is not in question. What is in question is how we obtain that concept. The attachment of the concept ( eg: 'zero') to the symbol ( eg: 'o') is easy, and not worth much thought. It is a technical matter for logicians, or scientists.
There are many views on how we obtain concepts like zero. Some say we learn a concept by seeing how it works. I think this is wrong, and a rather old view. You can see how things work (ie: what follows what), but there seems to be a conceptual understanding of a concept that cannot be capture by by just seeing how it works.
A technical example would be Godel theorem. One of the version of Godel theorem is that axiomatic system expressive enough to contain number theory would necessary be incomplete. By this, he means that there is a proposition in number theory that is true, but not proviable in the system.
eg: The meaning of say " every even number is the sum of two primes" could be true ( truth values are semantics), but not derived from the formal system.
If we interpret what it means to derive something as "showing it". There seems to be infinite many statements( in number theory) that are true, but not show able. The question then is "why do we know it is true?". The latter question is semantics.