ABSTRACT

Table 6.1 contains four subgroups of schemas. Schemas 1 through 7 are the core set of inference forms; they are used without restriction whenever they are applicable. Schemas 8 and 9 make inferences that are especially obvious, and Schema 8 could lead to an infinite loop if it were allowed to reapply continuously. They, along with Schema 1 in the rightto-left direction, and Schema 14 are called feeder schemas because the DRR constrains their application-they are used only when their output feeds another schema or the evaluation of a conclusion (apart from a permitted one-time use in reading out inferences).1 Schemas 10 and 11 define contradictions; the DRR uses them only in the Evaluation Procedure in bringing about the response of False. Schemas 12 and 13 have to do with suppositional reasoning, and they have very restricted roles in the DRR: Schema 12 is involved only in the Preliminary Procedure, and Schema 13 only in the falsification step of

the Evaluation Procedure. However, they have a prominent role in indirect (suppositional) reasoning (see later and chaps. 7 and 8 for examples and discussion of indirect reasoning). Schema 14 (a feeder schema) is placed at the end of the list because it is questionable whether it really belongs to the primary skills: It was taken as part of the primary skills in the work reported in chapter 7 (Braine et al., 1984) and in the design of the work reported in chapter 8; however, some of the data reported in chapter 8 made us question this assignment. The schema is included in Table 6.1 because it plays a role in the experiments and for ease of reference by the reader.