Aldo Leopold’s “Land Ethic” centers on the maxim: “A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.” I contribute to the critical appraisal of this maxim by providing answers to the following questions: (1) what is referred to by the phrase “the integrity, stability, and beauty of the biotic community”? (2) What “things” tend to preserve or threaten the integrity, stability, and beauty ofthe biotic (...) community? (3) Are the integrity, stability, and beauty ofthe biotic community goods such that preserving them is right and failing to do so wrong? (shrink)

We examine the evolution of the concept of stability in community ecology, arguing that biologists have moved from an emphasis on biotic communities characterized by static balance, to one of dynamic balance (returning to equilibrium after perturbation), to the current concept of stability as persistence. Using Wimsatt's (1987) analysis of how false models can often lead to better ones, we argue that failed attempts to link complexity with stability have significant heuristic value for community ecologists. Nevertheless, we argue that, (A) (...) because there is no common characteristic that stability terms presuppose, community ecology might be better served by abandoning the concept of stability and by employing instead specific terms such as 'persistence', 'resistance', and 'variability'. (B) The current emphasis (of stability terms) on persistence of species provides little basis for explaining possible mechanisms that might account for persistence. (shrink)

SUGGESTED COURSES Introductory level A (Requires very little background in logic .): 4: -9 - - -7 -2 Introductory level B: -9,:+-+ -,2:+,2: -,3:20+-22+ -7 -2 ...

In the middle of the 1980s, logical tools were discovered that make it possible to model changes in belief and knowledge in entirely new ways. These logical tools turned out to be applicable both to human beliefs and to the contents of databases. This is the first textbook in this new area. It contains both discursive chapters with a minimum of formalism and formal chapters in which proofs and proof methods are presented. By using different selections from the formal section (...) the book can be used on all levels of University education. (shrink)

Philosophers and ecologists have proposed that ecological principles such as cooperation and ecosystern stability serve as a basis for environmental ethics. Requisite to understanding whether a cooperation based environmental ethic can be taken as an unqualified good is knowledge of the role of cooperation in the context of other interactions between species (e.g., cornpetition), and the significance of such interactions to ecosystem stability. Further, since the key ecological concept of stability has been ambiguously defined, the various definitions need to be (...) understood so that use of scientific information in philosophical discussion is accurate and consistent. (shrink)

Different similarity relations on sets are introduced, and their logical properties are investigated. Close relationships are shown to hold between similarity relations that are based on symmetrical difference and operators of belief contraction that are based on relational selection functions. Two new rationality criteria for minimal belief contraction, the maximizing property and the reducing property, are proposed.

If we speak of degrees of similarity, what kinds of judgment are we assuming to make sense? It will be argued that the necessary and sufficient condition for there to be degrees of similarity is that there should be a four-termed relation of comparative similarity — w resembles x at least as much as y resembles z—obeying certain constraints. Of course, nothing turns on how we use the words 'degree of similarity'. Rather, the point is to distinguish the different levels (...) of ideologicalcommitment which different kinds of judgment of similarity involve. (shrink)

Formal representations of values and norms are employed in several academic disciplines and specialties, such as economics, jurisprudence, decision theory and social choice theory. Sven Ove Hansson closely examines such foundational issues as the values of wholes and the values of their parts, the connections between values and norms, how values can be decision-guiding and the structure of normative codes with formal precision. Models of change in both preferences and norms are offered, as well as a method to base the (...) logic of norms on that of preferences. Hansson has developed a unified formal representation of values and norms that reflects both their static and their dynamic properties. This formalized treatment, carried out in terms of both informal value theory and precise logical detail, will contribute to the clarification of certain issues in the basic philosophical theory of values and norms. (shrink)