Ehrenfeucht’s lemma asserts that whenever one element of a model of Peano arithmetic is definable from another, they satisfy different types. We consider here the analogue of Ehrenfeucht’s lemma for models of set theory. The original argument applies directly to the ordinal-definable elements of any model of set theory, and, in particular, Ehrenfeucht’s lemma holds fully for models of set theory satisfying V=HOD. We show that the lemma fails in the forcing extension of the universe by adding a Cohen real. (...) We go on to formulate a scheme of natural parametric generalizations of Ehrenfeucht’s lemma, namely, the principles of the form EL, which asserts that P-definability from A implies Q-discernibility. We also consider various analogues of Ehrenfeucht’s lemma obtained by using algebraicity in place of definability, where a set b is algebraic in a if it is a member of a finite set definable from a. Ehrenfeucht’s lemma holds for the ordinal-algebraic sets, we prove, if and only if the ordinal-algebraic and ordinal-definable sets coincide. Using a similar analysis, we answer two open questions posed earlier by the third author and C. Leahy, showing that algebraicity and definability need not coincide in models of set theory and the internal and external notions of being ordinal algebraic need not coincide. (shrink)

The path to consensus about physicians’ exercise of conscience was not linear. It looped back on itself as new insights illuminated earlier deliberations and in turn led to further insights. In particular, coming to agreement about physicians’ responsibility in regard to referral charted a route through many course corrections.

The precautionary principle holds that we should not allow scientific uncertainty to prevent us from taking precautionary measures in response to potential threats that are irreversible and potentially disastrous. Critics of the principle claim that it deters progress and development, is excessively risk-aversive and is unscientific. This paper argues that the principle can be scientific provided that (1) the threats addressed by the principle are plausible threats, and (2) the precautionary measures adopted are reasonable. The paper also argues that one (...) may use epistemic criteria, such as consistency, coherence and explanatory power, to determine whether a threat is plausible, and that one may use practical considerations, such as effectiveness, proportionality, cost-effectiveness, realism and consistency, to determine whether a response to a threat is reasonable. (shrink)

How good is psychotherapy as a tool of research into human nature? There is an orthodox defence of it as a research tool, which relies on showing that interpretations are true of the patient when they satisfy certain criteria. This defence is examined and rejected. The reply is considered that an interpretation which 'keeps things moving' is true, or an approximation to the truth. This reply is rejected by comparing and contrasting an interpretation in psychotherapy with one from brainwashing sessions. (...) Two suppositions about psychotherapy (which weaken its discovery powers) are deliberately adopted — the suppositions that the material produced is 'perspective' and 'method' dependent. An unorthodox defence of psychotherapy is then offered — by means of a watery sense of 'discover'. This enables us to outline a weak sense in which psychotherapy is a valid enterprise, but one which is still strong enough for research purposes. (shrink)

Lectures delivered under the auspices of the University of Poona.

If one were to find a date for the games put on by Pompey to celebrate the opening of his theatre in 55 B.C., it would be possible to assign a more precise date to the delivery of Cicero's speech in Pisonem than seems to have been done so far. Asconius states quite firmly that the in Pisonem was delivered in the second consulship of Pompey and Crassus, a few days before the lavish games celebrating the opening of Pompey's theatre. (...) Asconius rejects a counter-view that the speech was delivered late in the following year. (shrink)

The present account, based on introspective comments, deals with motivation and hedonic tone as subjective factors which affect continuous work at high speeds. Actual introspective reports are given. The earlier papers in the series described the experimental procedure and presented objective data.

volume 1. Developing institutional theory -- volume 2. New research agendas -- volume 3. Applying institutional theory.