Valentin's Blog

In a recent IEEE Intelligent Systems John F. Sowa wrote an interesting article that should be read be people interested in the logical side of the Semantic Web. Two of the quotes I particularly liked:

[...] computational complexity is important. But complexity is a property of algorithms, and only indirectly a property of problems, since most problems can be solved by different algorithms with different complexity. The language in which a problem is stated has no effect on complexity. Reducing the expressive power of a logic does not solve any problems faster; its only effect is to make some problems impossible to state.

and on Language and Logic:

What makes formal logic hard to use is its rigidity and its limited set of operators. Natural languages are richer, more expressive, and much more flexible. That flexibility permits vagueness, which some logicians consider a serious flaw, but a precise statement on any topic is impossible until all the details are determined. As a result, formal logic can only express the final result of a lengthy process of analysis and design. Natural language, however, can express every step from the earliest hunch or tentative suggestion to the finished specification.

In short, there are two equal and opposite fallacies about language and logic:  at one extreme, logic is unnatural and irrelevant; at the opposite extreme, language is incurably vague. A more balanced view must recognize the virtues of both:  logic is the basis for precise reasoning in every natural language; but without vagueness in the early stages of a project, it would be impossible to explore all the design options.

The entire article is available for free as a "preprint" here.

Labels: AI, SemanticWeb