In this paper we provide an analysis of various argumentation approaches (mainly due to Pollock) which explicitely deal with the notion of strength. While the attribution of a strength value to arguments seems to be necessary in actual practice, the basic meaning of the notion of strength is not clear, nor its role in resolving conflicts among arguments and determining their justification. The main contribution of the paper is to show that justification is not a purely epistemic notion, and a more articulated model of reasoning activity is a possible way to settle many problems emerging in existing approaches.
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