ABSTRACT
This chapter reveals the notion of top-down causation required to understand the operation of control hierarchies that figure prominently in biology and neuroscience. It considers organisms and discusses why control is more fundamental in understanding biological mechanisms than in the case of human-made machines. In the context of biology and neuroscience, controlled systems are commonly referred to as mechanisms. The chapter focuses on neural control, and emphasizes its importance in providing hierarchies of control in multicellular organisms whose component cells and mechanisms are endogenously active. It also emphasizes the top-down causation, as exhibited in the hierarchical control of biological mechanisms, is a fundamental feature of biological and neural systems. The ability of organisms to maintain themselves has, at times, led biologists to reject the quest for mechanistic explanations. In the early twentieth century, negative feedback was employed in numerous designs of machines and became the foundation of the notion of circular causality celebrated by the cyberneticists.
