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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)

In this paper a formalized logic of propositions, PA1, is presented. It is proven consistent and its relationships to traditional logic, to PM ([15]), to subjunctive (including contrary-to-fact) implication and to the “paradoxes” of material and strict implication are developed. Apart from any intrinsic merit it possesses, its chief significance lies in demonstrating the feasibility of a general logic containing theprinciple of subjunctive contrariety, i.e., the principle that ‘Ifpwere true thenqwould be true’ and ‘Ifpwere true thenqwould be false’ are incompatible.

Many social scientists and philosophers have counted themselves moral relativists in some sense or other. We cannot deal with all the various views which are properly called forms of “moral relativism”; so I propose to explain a form of moral relativism which seems to me an interesting, and somewhat plausible theory. This theory comprises the following three affirmations: The basic moral principles of different individuals or groups sometimes are, or can be, in some important sense conflicting. When there is such (...) fundamental conflict of basic principles or standards, there is either always, or at least sometimes, no way to show that one view is better justified even in the presence of ideally complete factual information; in that sense the principles are equally justified or “valid.” But there is a sense in which a particular moral belief may be mistaken or unjustified, if it is a misapplication of the basic principles of the individual or group, e.g., if the basic principles plus statements of known or knowable facts entail a moral proposition incompatible with it. As stated, moral relativism could be true even though in fact, accidentally, all individuals agree in their basic moral principles. (shrink)

One area in which the moral philosopher might say something useful for the thinking of economists is that of welfare economics – not by improving formalizations or criticizing proofs as to conditions necessary or sufficient for an optimum situation, much less by suggesting what particular state of society would be optimal. Rather, he can do this by pointing out some distinctions, by suggesting how some terms used by economists can profitably be defined, and by questioning some assumptions which seem to (...) lie behind the thinking of some economists. The following discussion is aimed along these lines. The main goal of the argument will be to produce helpful definitions of “increase the welfare of an individual” and “increase social welfare.”. (shrink)

Should we let personal responsibility for health-related behavior influence the allocation of healthcare resources? In this paper, we clarify what it means to be responsible for an action. We rely on a crucial conceptual distinction between being responsible and holding someone responsible, and show that even though we might be considered responsible and blameworthy for our health-related actions, there could still be well-justified reasons for not considering it reasonable to hold us responsible by giving us lower priority. We transform these (...) philosophical considerations into analytical use first by assessing the general features of health-related actions and the corresponding healthcare needs. Then, we identify clusters of structural features that even adversely affected people cannot reasonably deny constitute actions for which they should be held responsible. We summarize the results in an analytical framework that can be used by decision-makers when considering personal responsibility for health as a criterion for setting priorities. (shrink)

It is the aim of this paper to examine certain aspects of a point of view which has attracted much attention in physical methodology. This is the standpoint known as operationalism. We wish to discuss its significance in the construction and interpretation of physical theories.The essential meaning of operationalism in physics is that physical concepts should be defined in terms of actual physical operations. On this view there is no meaning to a concept unless it represents an operation which can (...) be performed in the laboratory. Thus the term “pressure of a gas” signifies nothing until an operation is described which constitutes the measurement of pressure. When one thinks of pressure one must think. of some actual apparatus, such as, for example, some glass and rubber tubing and some mercury and certain operations performed using these until finally one gets a pointer reading which one calls the pressure of the gas. The same stand is taken with respect to length, time, velocity, acceleration, temperature, etc. (shrink)

Virtually all philosophers now agree that human beings - and possibly the higher animals - have moral rights in some sense, both special rights against individuals to whom they stand in a special relation, and general rights, against everybody or against the government, just in virtue of their human nature. Some philosophers also think, however, that anyone who is a utilitarian ought not to share this view: there is a fundamental incompatibility between utilitarinism and human rights. Most utilitarians, of course, (...) have not thought there is such an incompatibility. John Stuart Mill, for instance, espoused utilitarianism at the same time that he defended rights to free speech and freedom of action except where it injures others. In what follows I wish to explore some reasons recently put forward to show that the utilitarian who wishes to affirm that there are moral rights faces a serious logical problem; and I shall argue that further analysis shows the alleged difficulty is unreal. (shrink)

The approach to teaching employed in the Dictionary of Medical Ethics (1) provides a model which might be adopted in other media. Most of the 150 authors were medical, but many represented other disciplines, and they wrote for similar professionals and for the general public. Medical ethics is derived from medical science and practice, moral philosophy, sociology, theology, the law and other disciplines, all of which make essential, distinctive and complementary contributions to knowledge and to teaching. Medical practitioners must play (...) the primary role, because they are responsible for clinical ethical decisions, but they need the co-operation and guidance of others. All who are concerned should work towards the development of a general moral consensus among the profession and public, which keeps abreast of scientific and technical advances and to which all are committed. (shrink)