It is often assumed that engaging in a one‐on‐one dialogue with a tutor is more effective than listening to a lecture or reading a text. Although earlier experiments have not always supported this hypothesis, this may be due in part to allowing the tutors to cover different content than the noninteractive instruction. In 7 experiments, we tested the interaction hypothesis under the constraint that (a) all students covered the same content during instruction, (b) the task domain was qualitative physics, (c) (...) the instruction was in natural language as opposed to mathematical or other formal languages, and (d) the instruction conformed with a widely observed pattern in human tutoring: Graesser, Person, and Magliano's 5‐step frame. In the experiments, we compared 2 kinds of human tutoring (spoken and computer mediated) with 2 kinds of natural‐language‐based computer tutoring (Why2‐Atlas and Why2‐AutoTutor) and 3 control conditions that involved studying texts. The results depended on whether the students' preparation matched the content of the instruction. When novices (students who had not taken college physics) studied content that was written for intermediates (students who had taken college physics), then tutorial dialogue was reliably more beneficial than less interactive instruction, with large effect sizes. When novices studied material written for novices or intermediates studied material written for intermediates, then tutorial dialogue was not reliably more effective than the text‐based control conditions. (shrink)

The environment has often been thought to consist of resources that are unowned, and hence subject to the well-known tragedy of the commons. But in recent years, property ideas have been increasingly recruited for environmental protection, in a manner that appears to vindicate the view that property rights evolve along with the needs for resource management. Nevertheless, property regimes have some pitfalls for environmental resources: the relevant parties may not be able to come to agreement; property regimes may be weak (...) or ineffective; they may be aimed at purposes inconsistent with environmental protection; property rights definitions may not work well for environmental resources; modern property regimes may promote monoculture rather than diverse environments. This essay describes these problems and asks to what degree they apply to a new effort to use property rights approaches, namely cap-and-trade programs to control greenhouse gases. It concludes that property rights, while imperfect and something of a retreat from a regime of complete liberty, may offer gains for environmental protection. But success will depend on close attention to the accountability and effectiveness of the governmental institutions necessary to support environmental property regimes. (shrink)

:A norm of equal treatment is cited regularly in the American jurisprudence of property “takings” under the Fifth and Fourteenth Amendments to the Constitution, as a benchmark of fair treatment of owners. According to an increasingly prevalent version of this equality norm, courts should look to parity of treatment among property owners in investigating whether particular regulations “take” property. This essay argues, however, that such an equality norm is misplaced, and that courts should judge fairness by the criterion of expectation—including (...) reasonable expectations of regulation.A norm of equality becomes problematic in the face of the economic theory of the evolution of property. This theory posits that as resources become more congested, their uses carry increasing common pool costs or “externalities”—a scenario that should predictably result in more stringent resource management—up to and including the establishment of regulatory regimes as well as property rights themselves. This evolutionary pattern, however, places earlier and later resource users in different positions vis-à-vis both common pool externalities and regulatory responses, and their different temporal positions fragment the meaning of equal treatment and destabilize it as a jurisprudential norm. This essay argues that while equal treatment may be a benchmark for special or invidious cases, like those relating to civil rights, the great bulk of takings cases involve regulatory responses to congesting resources, where a norm of equal treatment breaks down. Thus, in seeking fair treatment, takings jurisprudence should downplay equality and instead look to the understanding of property as a basis of expectations—but those expectations should include the anticipation of reasonable regulatory responses to resource congestion. (shrink)

In this paper I demonstrate that theories which postulate a strict tree structure of discourse on either the intentional or attentional level are not totally adequate for handling spontaneous dialogues. I use as..