A process, based on argumentation theory, is described for classifying very noisy data. More specifically a process founded on a concept called “arguing from experience” is described where by several software agents “argue” about the classification of a new example given individual “case bases” containing previously classified examples. Two “arguing from experience” protocols are described: PADUA which has been applied to binary classification problems and PISA which has been applied to multi-class problems. Evaluation of both PADUA and PISA indicates that they operate with equal effectiveness to other classification systems in the absence of noise. However, the systems out-perform comparable systems given very noisy data. Keywords: Classification, Argumentation, Noisy data.