The article first addresses the importance of cognitive modeling, in terms of its value to cognitive science (as well as other social and behavioral sciences). In particular, it emphasizes the use of cognitive architectures in this undertaking. Based on this approach, the article addresses, in detail, the idea of a multi-level approach that ranges from social to neural levels. In physical sciences, a rigorous set of theories is a hierarchy of descriptions/explanations, in which causal relationships among entities at a high (...) level can be reduced to causal relationships among simpler entities at a more detailed level. We argue that a similar hierarchy makes possible an equally productive approach toward cognitive modeling. The levels of models that we conceive in relation to cognition include, at the highest level, sociological/anthropological models of collective human behavior, behavioral models of individual performance, cognitive models involving detailed mechanisms, representations, and processes, as well as biological/physiological models of neural circuits, brain regions, and other detailed biological processes. (shrink)

This book is about an important issue which has arisen within two of the branches of physical science - namely thermodynamics and statistical mechanics - where the notion of entropy plays an essential role. A number of scientists and information theorists have maintained that entropy is a subjective concept and is a measure of human ignorance. Such a view, if it is valid, would create some profound philosophical problems and would tend to undermine the objectivity of the scientific enterprise. Whilst (...) the present volume is not a treatise on thermodynamics or statistical mechanics, all relevant steps in the building up of these disciplines are carefully scrutinised and it is concluded that the charge of subjectivity cannot be upheld. The widely adopted view that entropy is a measure of disorder, or of lack of information, is shown to be ambiguous, although it may be of use in certain contexts. (shrink)

Some of the most imaginative analyses in contemporary science have been fostered by the paradox of irreversibility. Rendered as a question the paradox reads: How can the anisotropic macrophysical behavior of a system of molecules be reconciled with the underlying reversible molecular model? Attempts to resolve and dissolve the paradox have appealed to large numbers of particles, jammed correlations, unseen perturbations, hidden variables or constraints, uncertainty principles, averaging procedures (e.g., coarse graining and time smoothing), stochastic flaws, cosmological origins, etc. While (...) acknowledging these efforts as important articulations of basic ideas of statistical mechanics, we question their relevance to irreversibility as it occurs in nature. It seems to us that once the emergence of the phenomenon of equilibrium is understood in terms of molecular dynamics, the macroscopic appearance of irreversibility can also be understood in terms of the frequency of forced withdrawals from young equilibria. We believe that the paradox of irreversibility can be resolved in a simple, logically clear, and aesthetically pleasing manner. (shrink)