Individual semiotic systems interpreting their environment are not well understood from the externalist approach typical of the scientific method. Science constructs probabilities describing large populations of systems, not individuals. The Umwelt, as the individually experienced/created aspects of the habitat aspect of its population’s ecological niche, is given an internalist understanding within the framework of the compositional hierarchy. Vagueness is an important aspect of the internalist condition. It is selectively reduced momentarily by creative choices that can have a Peircean semiotic formulation, (...) and which are often unpredictable externally, thereby appearing to be chance events. (shrink)

To controlforceaccurately under a wide range of behavioral conditions, the central nervous system would either require a detailed, continuously updated representation of the state of each muscle (and the load against which each is acting) or else force feedback with sufficient gain to cope with variations in the properties of the muscles and loads. The evidence for force feedback with adequate gain or for an appropriate central representation is not sufficient to conclude that force is the major controlled variable in (...) normal limb movements.Morton's hypothesis, thatlengthis controlled by a follow-up servo, has a number of difficulties related to the delays, gains, variability, and specificity in feedback pathways comprising potential servo loops. However, experimental evidence is consistent with these pathways providing servo assistance for some movements produced by coactivation of α- and static γ-motoneurons. Dynamic γ-motoneurons may provide an additional input for adaptive control of different types of movements.The idea that feedback is used to compensate for changes in musclestiffnesshas received experimental support under static postural conditions. However, reflexes tend to increase rather than decrease the range of variation in muscle stiffness during some cyclic movements. Theoretical problems associated with the regulation of stiffness are also discussed. The possibilities of separate control systems forvelocityorviscosityare considered, but the evidence is either negative or lacking. I conclude that different physical variables can be controlled depending on the type of limb movement required. The concept of stiffness regulation is also useful under some conditions, but should probably be extended to the regulation of the visco-elastic properties (i.e., the mechanical impedance) of a muscle or joint. (shrink)

The subject of (ir)reducibility in biochemistry has resurfaced recently in the literature. Along with it comes a renewed emphasis on the organizational complexity of the living state and, more broadly, concern over the unity of the sciences.