A New Prescription for Protogalactic Feedback and Outflows: Where Have All the Baryons Gone?

Up to half of the baryons inferred to once have been in our galaxy have not yet been detected. Ejection would seem to provide the most attractive explanation. Previous numerical studies may have underestimated the role of winds. I propose a solution involving a multiphase model of the protogalactic interstellar medium and the possibility of driving a superwind. Simulations do not yet incorporate the small-scale physics that, I argue, drives mass-loading of the cold phase gas and enhances the porosity, thereby ensuring that winds are driven at a rate that depends primarily on the star formation rate. The occurrence of hypernovae, as claimed for metal-poor and possibly also for starburst environments, and the possibility of a top-heavy primordial stellar initial mass function are likely to have played important roles in allowing winds to prevail in massive gas-rich starbursting protogalaxies as well as in dwarfs. I discuss why such outflows are generically of order the rate of star formation and may have been a common occurrence in the past.Comment: MNRAS, in press (2003): minor revisions include

Dark Matter and Galaxy Formation: Challenges for the Next Decade

The origin of the galaxies represents an important focus of current cosmological research, both observational and theoretical. Its resolution involves a comprehensive understanding of star formation, galaxy dynamics, the cosmology of the very early universe, and the nature of the dark matter. In this review, I will focus on those aspects of dark matter that are relevant for understanding galaxy formation, and describe the outlook for detecting the most elusive component, non-baryonic dark matter.Comment: To be published in joint proceedings for Mitchell Symposium on Observational Cosmology and Strings and Cosmology Conference, College Station, April 2004, eds. R. Allen and C. Pope, AIP, New York, and in proceedings for PASCOS04/NathFest, Boston, August 2004, eds. G. Alverson and M. Vaughan, World Scientific, Singapor

Expectation Biases and Context Management with Negative Polar Questions

This paper examines distinctive discourse properties of preposed negative 'yes/no' questions (NPQs), such as 'Isn’t Jane coming too?'. Unlike with other 'yes/no' questions, using an NPQ '∼p?' invariably conveys a bias toward a particular answer, where the polarity of the bias is opposite of the polarity of the question: using the negative question '∼p?' invariably expresses that the speaker previously expected the positive answer p to be correct. A prominent approach—what I call the context-management approach, developed most extensively by Romero and Han (2004)—attempts to capture speaker expectation biases by treating NPQs fundamentally as epistemic questions about the proper discourse status of a proposition. I raise challenges for existing context-managing accounts to provide more adequate formalizations of the posited context-managing content, its implementation in the compositional semantics and discourse dynamics, and its role in generating the observed biases. New data regarding discourse differences between NPQs and associated epistemic modal questions are introduced. I argue that we can capture the roles of NPQs in expressing speakers’ states of mind and managing the discourse common ground without positing special context-managing operators or treating NPQs as questions directly about the context. I suggest that we treat the operator introduced with preposed negation as having an ordinary semantics of epistemic necessity, though lexically associated with a general kind of endorsing use observed with modal expressions. The expressive and context-managing roles of NPQs are explained in terms of a general kind of discourse-oriented use of context-sensitive language. The distinctive expectation biases and discourse properties observed with NPQs are derived from the proposed semantics and a general principle of Discourse Relevance

Nietzsche and contemporary metaethics

Recent decades have witnessed a flurry of interest in Nietzsche's metaethics — his views, if any, on metaphysical, epistemological, semantic, and psychological issues about normativity and normative language and judgment. Various authors have highlighted a tension between Nietzsche's metaethical views about value and his ardent endorsement of a particular evaluative perspective: Although Nietzsche makes apparently "antirealist" claims to the effect that there are no evaluative facts, he vehemently engages in evaluative discourse and enjoins the "free spirits" to create values. Nearly every major type of metaethical "-ism" has been ascribed to Nietzsche in response. This chapter provides a critical introduction to Nietzsche's metaethics, focusing on matters concerning the nature and grounds of normativity. I begin by examining and raising challenges for Nadeem Hussain's prominent interpretation of Nietzsche as a revolutionary fictionalist. I argue that a constructivist interpretation (developed elsewhere) provides an improved account of the connections, for Nietzsche, between evaluative attitudes and the nature of value, and among practical nihilism, art, and value creation. Values, on this view, are treated as grounded purely in facts about creatures’ evaluative attitudes. The chapter concludes by considering several alternative subjectivist, constitutivist, and non-cognitivist interpretations. A nuanced understanding of the space of metaethical theories brings into relief a plausible normative and metanormative view that we can attribute to Nietzsche

What normative terms mean and why it matters for ethical theory

This paper investigates how inquiry into normative language can improve substantive normative theorizing. First I examine two dimensions along which normative language differs: “strength” and “subjectivity.” Next I show how greater sensitivity to these features of the meaning and use of normative language can illuminate debates about three issues in ethics: the coherence of moral dilemmas, the possibility of supererogatory acts, and the connection between making a normative judgment and being motivated to act accordingly. The paper concludes with several brief reflections on the theoretical utility of the distinction—at least so-called—between “normative” and “non-normative” language and judgment. Clarifying the language we use in normative conversation and theorizing can help us diagnose problems with bad arguments and formulate better motivated questions. This can lead to clearer answers and bring into relief new theoretical possibilities and avenues to explore

Theories of vagueness and theories of law

It is common to think that what theory of linguistic vagueness is correct has implications for debates in philosophy of law. I disagree. I argue that the implications of particular theories of vagueness on substantive issues of legal theory and practice are less far-reaching than often thought. I focus on four putative implications discussed in the literature concerning (i) the value of vagueness in the law, (ii) the possibility and value of legal indeterminacy, (iii) the possibility of the rule of law, and (iv) strong discretion. I conclude with some methodological remarks. Delineating questions about conventional meaning, the metaphysics/metasemantics of (legal) content determination, and norms of legal interpretation and judicial practice can motivate clearer answers and a more refined understanding of the space of overall theories of vagueness, interpretation, and law