ABSTRACT
One disadvantage of writing about argumentation is that its subject matter itself is a nagging reminder of the need to be alert to weaknesses in the arguments being offered in support of one view rather than another. If too many fault lines begin to appear, an incipient earthquake might shake any growing edifice into ruins. The fault lines that emerged while reflecting on how to establish solid foundations for evaluating the truth of beliefs and the validity and strength of arguments did finally lead me to a reconceptualization of the ideas of 'invalidity' and of 'fallacy' or 'error.' I decided that the use of such categorical terms is best confined to:
1. Beliefs that are actually inconsistent with currently available evidence (with implausible being appropriate for beliefs where the weight of evidence is against them);
2. Arguments whose formal linkages are inconsistent with valid patterns of inference.
