acquisitions beyond that core. Piaget, on the other hand, continued to
maintain that all acquisitions, both competencies and procedures are con-
structions, produced out of the assimilation/accommodation equilibration
process. Braine roots the nativist component of his perspective in evolution-
ary theory, whereas Moshman discusses later acquisitions in terms of meta-
logical understanding and metalogical strategies.

Falmagne (Chap. 6), offers a unique argument for the origin and devel-
opment of logical competence in her discussion of the role played by lan-
guage. She argues that although the origins of logical competence might be,
as suggested by Piaget, sensorimotor in nature, higher forms of logical com-
petence may be derivable from linguistic structures themselves. She further
suggests processes according to which this acquisition may occur, and
presents several empirical studies in support of her position.

Scholnick (Chap. 8) returns the focus to the nature of deductive reason-
ing through an analysis of the positions held by several of the authors of the
present volume, as well as several other contemporary investigators (e.g.,
Case; Johnson-Laird). Scholnick's analysis leads her to suggest that, in ad-
dition to propositional factors and semantic factors, a complete understand-
ing of deductive reasoning requires the introduction of presuppositional
factors. Presuppositions set a pragmatic frame for deductive reasoning, and
Scholnick presents several of her own studies that illustrate this role.

Because deduction yields necessity, throughout this book the develop-
ment of the concept of necessity is explored as a reflection of the develop-
ment of a system of logical competence (see especially Chaps. 1, 3, 8, and
10). However, in Chapter 9, Murray directly examines the development of
this important concept. Murray presents a number of empirical illustrations
arising out of his own work on conservation, and goes on to argue that the
Genevan theory of equilibration provides a plausible account of the devel-
opment of the concept of necessity.

In Chapter 12, Black and I explore the relevance of deductive reasoning
to the important applied problem of thought disorders. We review the his-
torical literature that has suggested that thought disorders represent a fail-
ure of deductive reasoning, and we examine this issue in the light of our
contemporary understanding of the nature and development of deductive
reasoning.

Finally, Keating (Chap. 13) presents several criticisms of the literature on
formal operational thinking that emerge from a deconstructionist and re-
constructionist theoretical perspective. Keating's understanding of this per-
spective, tends to lean heavily in the direction of philosophical realism. As a
consequence, his comments often have the familiar ring of the empiricist
confronting the rationalist or interpretationist. However, his general caution
that there is a limit to reasoning can well be heeded by both groups. Deduc-
tive reasoning is a central and essential type of thinking, as it is a central
and essential cognitive process. As such, its nature, origin, and development

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