Charles L. Hamblin

Charles Hamblin (1922-1985) was an Australian philosopher and pioneer computer scientist. In philosophy, his main contribution was a novel study of the classical logical fallacies, using the formal dialogue games first studied by Aristotle. His book, Fallacies (1970), is still in print.

In computer science, Hamblin was the originator of the recursive stack (or last-in, first-out store), an idea which first saw implementation in 1957 at the then New South Wales University of Technology (now the University of New South Wales) in Sydney in the programming language GEORGE (General Order Generator). GEORGE was a programming system written for a DEUCE computer at NSWUT and appears to have been the first programming language to use Reverse Polish Notation, which Hamblin invented. Hamblin's work inspired the design of the KDF9 computer of the English Electric Company, announced in 1960 and delivered in 1963.

Hamblin's proposal for Reverse Polish Notation is contained in the following papers. The first paper also proposed stacks.

C. L. Hamblin [1957]: "Computer Languages." The Australian Journal of Science, 20: 135-139. Reprinted in The Australian Computer Journal, 17(4): 195-198 (November 1985).

C. L. Hamblin [1962]: "Translation to and from Polish notation." Computer Journal, 5: 210-213.

Hamblin studied Mathematics, Physics and Philosophy at Melbourne University, with his studies interrupted by work as a radar officer in the Royal Australian Air Force during World War II. He did a PhD at London University entitled "Language and the Theory of Information". Between 1955 and his death in 1985 he was a Lecturer and Professor in the School of Philosophy at the University of New South Wales. Hamblin apparently died from an illness acquired while attempting to set words of Wittgenstein to music, which perhaps shows the perils of that philosopher's ideas.

His importance to computer science is shown by the fact that he was given an obituary in The Australian Computer Journal (Allen 1985), the same issue of which also reprinted his 1957 article on computer languages cited above.

M. W. Allen [1985]: "Charles Hamblin (1922-1985)" The Australian Computer Journal, 17(4): 194-195.

The obituary noted presciently: "It could be that his work on logic which takes into account the human factor will yet have considerable relevance in this area [of intelligent systems]." Hamblin's approach to formal dialogue games has been influential in the design of interaction protocols for multi-agent systems, in the design of human-machine interfaces, and in natural language processing. Moreover, his use of dialogue games to study fallacious arguments may also be seen as an instance of a game-theoretic semantics, a concept of great influence in the theory of programming languages.

Hamblin also appears to have been the first person to define a formal measure of plausibility, distinct from that of probability, in a paper published in 1959. Alternative formalisms for uncertainty have come to play a very important role in Artificial Intelligence, particularly in the design of knowledge-based systems, due to the failure of the standard Kolmogorov axioms of probability to adequately account for all forms of uncertainty and its manipulation. Hamblin's contribution appears to have been overlooked in this area, however.

C. L. Hamblin [1959]: "The Modal "Probably" ", Mind, New Series, 68: 234-240.

Hamblin's contribution has also been recognized in this timeline of events in the history of computing, published by the Australian Computer Museum Society.

I have also written a longer biography of Charles Hamblin for the Australian Computer Museum Society.

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