Robert Schwartz

Roger Shepard's proposals and supporting experiments concerning evolutionary internalized regularities have been very influential in the study of vision and in other areas of psychology and cognitive science. This paper examines issues concerning the need, nature, explanatory role, and justification for postulating such internalized constraints. In particular, I seek further clarification from Shepard on how best to understand his claim that principles of kinematic geometry underlie phenomena of motion perception. My primary focus is on the ecological validity of Shepard's kinematic constraint in the context of ordinary motion perception. First, I explore the analogy Shepard draws between internalized circadian rhythms and the supposed internalization of kinematic geometry. Next, questions are raised about how to interpret and justify applying results from his own and others' experimental studies of apparent motion to more everyday cases of motion perception in richer environments. Finally, some difficulties with Shepard's account of the evolutionary development of his kinematic constraint are considered. Key Words: apparent motion; circadian rhythms; constraints; ecological validity; evolution; internalizated regularities; kinematic principle.

Recently it has been argued that a model of directed perception provides an alternative to both indirect and direct accounts of the nature of vision. An examination of this proposal serves as a basis for challenging the meaningfulness and empirical import of the theoretical and ontological differences said to separate these models. Although focusing on James Cutting's work, the analysis is meant to speak more generally to the supposed significance of the distinctions among indirect, direct, and directed theories of perception

Most of us find the surgeon's surprise at this patient' request understandable, and it is hard to imagine any surgeon acceding to this patient's demand. On the other hand, the patient is right—the surgeon is denying his technical skill because his values are different from those of the patient, whose values the surgeon does not respect. The autonomy of the patient is being limited by the values of the doctor whose own interests, other than his interest in practicing medicine according to his own ethical values, would remain unaffected by his decision to provide the service

In many countries the debate over the role that physicians may play in ending life has been limited to the judiciary and other law making institutions, professional medical organizations; and academics. Because of their multidisciplinary and diverse membership, ethics committees may be a particularly appropriate venue through which these discussions can be expanded to include a much larger community. In addition, ethics committees generally act in only advisory capacities because they do not actually make decisions, so they may provide a forum for open discussions in ways that the court and the medical boards cannot

As ethics committees become involved in discussing the propriety of euthanasia and assisted suicide, and as healthcare providers begin to seriously consider whether they might ever have a role in hastening the dying process, many have looked to The Netherlands as the only real example of a nation that permits euthanasia in limited circumstances. Unfortunately, partisans in the Dutch debate have often written about the Dutch experience as advocates rather than as neutral observers. Some have argued that euthanasia, which, they claim, is rarely actually practiced, is universally accepted within The Netherlands; others have reported that the Dutch social fabric has been rended irreparably by what they claim, is a practice far more widespread than is generally understood. The debate in the United States has also been colored by a misunderstanding of the legal regulation of euthanasia in The Netherlands

Over the past year the debate over physician-assisted death has been waged in several courts and legislatures, and before at least one electorate as well. Measure 16, the Oregon Death With Dignity initiative that would permit physician-assisted suicide in some circumstances, was approved by the electorate; but it remains on hold while a permanent injunction issued against it by a Federal judge is reviewed by the United States Court of Appeals. Another Federal court judge's decision that the Washington statute criminalizing physician-assisted suicide was unconstitutional when applied to the case of a competent terminally ill patient in intractable pain, was reversed by a three judge panel of that same United States Court of Appeals