Formalizations of commonsense knowledge rely on highly simplified representations of the world. After a conclusion is justified on the basis of one such representation in a non? monotonic logic, it may not remain valid when additional rel? evant facts are taken into account to bring the formalization to a closer approximation of reality. However, if the conclu? sion continues to hold in the enriched theory, we can consider it to be reinforced. An argument in support of a claim can be represented by a sequence of nonmonotonic theories, each containing and enhancing the previous theory in the sequence and each entailing the claim. This idea is illustrated here by a sequence of formalizations of ``Sam's Calculus''---an exam? ple of commonsense reasoning due to Ernie Davis---in the language of the Causal Calculator.

PS

unpublished. In {em Working Notes of the AAAI Spring Symposium on Logical Formalizations of Commonsense Reasoning}.

@UNPUBLISHED{cam03, title={Reinforcing a Claim in Commonsense Reasoning}, author={Jonathan Campbell and Vladimir Lifschitz}, pages={51-56}, note={In {em Working Notes of the AAAI Spring Symposium on Logical Formalizations of Commonsense Reasoning}}, url="http://www.cs.utexas.edu/users/ai-lab?cam03", year={2003} }