There is no broadly accepted definition of ‘life.’ Suggested definitions face problems, often in the form of robust counter-examples. Here we use insights from philosophical investigations into language to argue that defining ‘life’ currently poses a dilemma analogous to that faced by those hoping to define ‘water’ before the existence of molecular theory. In the absence of an analogous theory of the nature of living systems, interminable controversy over the definition of life is inescapable.

In earlier work ( Cleland [2001] , [2002]), I sketched an account of the structure and justification of ‘prototypical’ historical natural science that distinguishes it from ‘classical’ experimental science. This article expands upon this work, focusing upon the close connection between explanation and justification in the historical natural sciences. I argue that confirmation and disconfirmation in these fields depends primarily upon the explanatory (versus predictive or retrodictive) success or failure of hypotheses vis-à-vis empirical evidence. The account of historical explanation that (...) I develop is a version of common cause explanation. Common cause explanation has long been vindicated by appealing to the principle of the common cause. Many philosophers of science (e.g., Sober and Tucker) find this principle problematic, however, because they believe that it is either purely methodological or strictly metaphysical. I defend a third possibility: the principle of the common cause derives its justification from a physically pervasive time asymmetry of causation (a.k.a. the asymmetry of overdetermination). I argue that explicating the principle of the common cause in terms of the asymmetry of overdetermination illuminates some otherwise puzzling features of the practices of historical natural scientists. (shrink)

The Church-Turing thesis makes a bold claim about the theoretical limits to computation. It is based upon independent analyses of the general notion of an effective procedure proposed by Alan Turing and Alonzo Church in the 1930''s. As originally construed, the thesis applied only to the number theoretic functions; it amounted to the claim that there were no number theoretic functions which couldn''t be computed by a Turing machine but could be computed by means of some other kind of effective (...) procedure. Since that time, however, other interpretations of the thesis have appeared in the literature. In this paper I identify three domains of application which have been claimed for the thesis: (1) the number theoretic functions; (2) all functions; (3) mental and/or physical phenomena. Subsequently, I provide an analysis of our intuitive concept of a procedure which, unlike Turing''s, is based upon ordinary, everyday procedures such as recipes, directions and methods; I call them mundane procedures. I argue that mundane procedures can be said to be effective in the same sense in which Turing machine procedures can be said to be effective. I also argue that mundane procedures differ from Turing machine procedures in a fundamental way, viz., the former, but not the latter, generate causal processes. I apply my analysis to all three of the above mentioned interpretations of the Church-Turing thesis, arguing that the thesis is (i) clearly false under interpretation (3), (ii) false in at least some possible worlds (perhaps even in the actual world) under interpretation (2), and (iii) very much open to question under interpretation (1). (shrink)

: Despite its amazing morphological diversity, life as we know it on Earth today is remarkably similar in its basic molecular architecture and biochemistry. The assumption that all life on Earth today shares these molecular and biochemical features is part of the paradigm of modern biology. This paper examines the possibility that this assumption is false, more specifically, that the contemporary Earth contains as yet unrecognized alternative forms of microbial life. The possibility that more than one form of life arose (...) on Earth is consistent with our current understanding of conditions on the early Earth and the biochemical and molecular possibilities for life. Arguments that microbial descendents of an alternative origin of life could not co-exist with familiar life are belied by what we know of the complexity and diversity of microbial communities. Furthermore, the tools that are currently used to explore the microbial world – microscopy (with the aid of techniques such as DAPI staining and fluorescence in situ hybridization), cultivation and PCR amplification of rRNA genes – could not detect such organisms if they existed. Thus, the fact that we have not discovered any alternative life forms cannot be taken as evidence that they do not exist. (shrink)

Experimental research is commonly held up as the paradigm of "good" science. Although experiment plays many roles in science, its classical role is testing hypotheses in controlled laboratory settings. Historical science is sometimes held to be inferior on the grounds that its hypothesis cannot be tested by controlled laboratory experiments. Using contemporary examples from diverse scientific disciplines, this paper explores differences in practice between historical and experimental research vis-à-vis the testing of hypotheses. It rejects the claim that historical research is (...) epistemically inferior. For as I argue, scientists engage in two very different patterns of evidential reasoning and, although there is overlap, one pattern predominates in historical research and the other pattern predominates in classical experimental research. I show that these different patterns of reasoning are grounded in an objective and remarkably pervasive time asymmetry of nature. (shrink)

Horsten and Roelants have raised a number of important questions about my analysis of effective procedures and my evaluation of the Church-Turing thesis. They suggest that, on my account, effective procedures cannot enter the mathematical world because they have a built-in component of causality, and, hence, that my arguments against the Church-Turing thesis miss the mark. Unfortunately, however, their reasoning is based upon a number of misunderstandings. Effective mundane procedures do not, on my view, provide an analysis of ourgeneral concept (...) of an effective procedure; mundane procedures and Turing machine procedures are different kinds of procedure. Moreover, the same sequence ofparticular physical action can realize both a mundane procedure and a Turing machine procedure; it is sequences of particular physical actions, not mundane procedures, which enter the world of mathematics. I conclude by discussing whether genuinely continuous physical processes can enter the world of real numbers and compute real-valued functions. I argue that the same kind of correspondence assumptions that are made between non-numerical structures and the natural numbers, in the case of Turing machines and personal computers, can be made in the case of genuinely continuous, physical processes and the real numbers. (shrink)

The question ‘what is life?’ has long been a source of philosophical debate and in recent years has taken on increasing scientific importance. The most popular approach among both philosophers and scientists for answering this question is to provide a “definition” of life. In this article I explore a variety of different definitional approaches, both traditional and non-traditional, that have been used to “define” life. I argue that all of them are deeply flawed. It is my contention that a scientifically (...) compelling understanding of the nature of life presupposes an empirically adequate scientific theory (vs. definition) of life; as I argue, scientific theories are not the sort of thing that can be encapsulated in definitions. Unfortunately, as I also discuss, scientists are currently in no position to formulate even a tentative version of such a theory. Recent discoveries in biology and biochemistry have revealed that familiar Earth life represents a single example that may not be representative of life. If this is the case, life on Earth today provides an empirically inadequate foundation for theorizing about life considered generally. I sketch a strategy for procuring the needed additional examples of life without the guidance of a definition or theory of life, and close with an application to NASA’s fledgling search for extraterrestrial life. (shrink)

Is one of the roles of theory in biology answering the question “What is life?” This is true of theory in many other fields of science. So why should not it be the case for biology? Yet efforts to identify unifying concepts and principles of life have been disappointing, leading some (pluralists) to conclude that life is not a natural kind. In this essay I argue that such judgments are premature. Life as we know it on Earth today represents a (...) single example and moreover there is positive evidence that it may be unrepresentative of life considered generally. Furthermore, as I discuss, the prototype for theorizing about life has traditionally been based on multicellular plants and animals. Yet biologists have discovered that the latter represent a rare, exotic, and fairly recent form of Earth life. By far the oldest, toughest, most extensive, and diverse form of life on our planet is unicellular, prokaryotic microbes, and there are reasons to suppose that this is almost certainly true elsewhere in the universe as well. If there are explanatorily and predictively powerful, biologically distinctive principles for life that can be gleaned from our insular example of life it is more likely that they will be found among the microbes. I discuss some provocative ways in which unicellular microbes differ from multicellular eukaryotes and argue that some of them just might provide us with key insights into the nature of life. (shrink)

This chapter contains sections titled: Introduction The Scientific Method of Yore The Structure and Research Practices of Scientific Historiography of Nature Explanation and Confirmation in Scientific Historiography Narrative Explanation Common Cause Explanation References.

The assumption that all life on Earth today shares the same basic molecular architecture and biochemistry is part of the paradigm of modern biology. This paper argues that there is little theoretical or empirical support for this widely held assumption. Scientists know that life could have been at least modestly different at the molecular level and it is clear that alternative molecular building blocks for life were available on the early Earth. If the emergence of life is, like other natural (...) phenomena, highly probable given the right chemical and physical conditions then it seems likely that the early Earth hosted multiple origins of life, some of which produced chemical variations on life as we know it. While these points are often conceded, it is nevertheless maintained that any primitive alternatives to familiar life would have been eliminated long ago, either amalgamated into a single form of life through lateral gene transfer or alternatively out-competed by our putatively more evolutionarily robust form of life. Besides, the argument continues, if such life forms still existed, we surely would have encountered telling signs of them by now. These arguments do not hold up well under close scrutiny. They reflect a host of assumptions that are grounded in our experience with large multicellular organisms and, most importantly, do not apply to microbial forms of life, which cannot be easily studied without the aid of sophisticated technologies. Significantly, the most powerful molecular biology techniques available—polymerase chain reaction amplification of rRNA genes augmented by metagenomic analysis—could not detect such microbes if they existed. Given the profound philosophical and scientific importance that such a discovery would represent, a dedicated search for ‘shadow microbes’ seems in order. The best place to start such a search is with puzzling phenomena, such as desert varnish, that resist classification as ‘biological’ or ‘nonbiological’. (shrink)

This chapter argues that doubts about the scientific status of the field sciences often rest on mistaken preconceptions about the nature of the evaluative relation between empirical evidence and hypothesis or theory, namely, that it is some sort of formal logical relation. It argues that there is a potentially more fruitful approach to understanding the nature of the support offered by empirical evidence to scientific hypotheses. The first part of the chapter briefly reviews the traditional philosophical take on the scientific (...) method in order to clarify its most serious problems. It shows that these problems are greatly exacerbated when science moves from the artificially controlled environment of the laboratory to the messy uncontrollable world of nature. The second part ferrets out some highly general, causal components in the methodological reasoning of nonhistorical field scientists. It argues that differences in patterns of evidential reasoning in the experimental sciences versus the field sciences, and in the historical versus nonhistorical field sciences, seem tailored to pervasive causal differences in their epistemic situations. (shrink)

In the technical literature of computer science, the concept of an effective procedure is closely associated with the notion of an instruction that precisely specifies an action. Turing machine instructions are held up as providing paragons of instructions that "precisely describe" or "well define" the actions they prescribe. Numerical algorithms and computer programs are judged effective just insofar as they are thought to be translatable into Turing machine programs. Nontechnical procedures (e.g., recipes, methods) are summarily dismissed as ineffective on the (...) grounds that their instructions lack the requisite precision. But despite the pivotal role played by the notion of a precisely specified instruction in classifying procedures as effective and ineffective, little attention has been paid to the manner in which instructions "precisely specify" the actions they prescribe. It is the purpose of this paper to remedy this defect. The results are startling. The reputed exemplary precision of Turing machine instructions turns out to be a myth. Indeed, the most precise specifications of action are provided not by the procedures of theoretical computer science and mathematics (algorithms) but rather by the nontechnical procedures of everyday life. I close with a discussion of some of the rumifications of these conclusions for understanding and designing concrete computers and their programming languages. (shrink)

Pluralism is popular among philosophers of biology. This essay argues that negative judgments about universal biology, while understandable, are very premature. Familiar life on Earth represents a single example of life and, most importantly, there are empirical as well as theoretical reasons for suspecting that it may be unrepresentative. Scientifically compelling generalizations about the unity of life must await the discovery of forms of life descended from an alternative origin, the most promising candidate being the discovery of extraterrestrial life. Nonetheless, (...) in the absence of additional examples of life, we are best off exploring the microbial world for promising explanatory concepts, principles, and mechanisms rather than prematurely giving up on universal biology. Unicellular microbes are by far the oldest, metabolically most diverse, and environmentally tolerant form of life on our planet. Yet somewhat ironically, much of our theorizing about life still implicitly privileges complex multicellular eukaryotes, which are now understood to be highly specialized, fragile latecomers to Earth. The problem with pursuing a pluralist approach to understanding life is that it is likely to blind us to the significance of just those entities and causal processes most likely to shed light on the underlying nature of life. (shrink)

Since the mid-twentieth century, the concept of the Turing machine has dominated thought about effective procedures. This paper presents an alternative to Turing's analysis; it unifies, refines, and extends my earlier work on this topic. I show that Turing machines cannot live up to their billing as paragons of effective procedure; at best, they may be said to provide us with mere procedure schemas. I argue that the concept of an effective procedure crucially depends upon distinguishing procedures as definite courses (...) of action(- types) from the particular courses of action(-tokens) that actually instantiate them and the causal processes and/or interpretations that ultimately make them effective. On my analysis, effectiveness is not just a matter of logical form; `content' matters. The analysis I provide has the advantage of applying to ordinary, everyday procedures such as recipes and methods, as well as the more refined procedures of mathematics and computer science. It also has the virtue of making better sense of the physical possibilities for hypercomputation than the received view and its extensions, e.g. Turing's o-machines, accelerating machines. (shrink)

The assumption that all life on Earth today shares the same basic molecular architecture and biochemistry is part of the paradigm of modern biology. This paper argues that there is little theoretical or empirical support for this widely held assumption. Scientists know that life could have been at least modestly different at the molecular level and it is clear that alternative molecular building blocks for life were available on the early Earth. If the emergence of life is, like other natural (...) phenomena, highly probable given the right chemical and physical conditions then it seems likely that the early Earth hosted multiple origins of life, some of which produced chemical variations on life as we know it. While these points are often conceded, it is nevertheless maintained that any primitive alternatives to familiar life would have been eliminated long ago, either amalgamated into a single form of life through lateral gene transfer (LGT) or alternatively out-competed by our putatively more evolutionarily robust form of life. Besides, the argument continues, if such life forms still existed, we surely would have encountered telling signs of them by now. These arguments do not hold up well under close scrutiny. They reflect a host of assumptions that are grounded in our experience with large multicellular organisms and, most importantly, do not apply to microbial forms of life, which cannot be easily studied without the aid of sophisticated technologies. Significantly, the most powerful molecular biology techniques available—polymerase chain reaction (PCR) amplification of rRNA genes augmented by metagenomic analysis—could not detect such microbes if they existed. Given the profound philosophical and scientific importance that such a discovery would represent, a dedicated search for ‘shadow microbes’ (heretofore unrecognized ‘alien’ forms of terran microbial life) seems in order. The best place to start such a search is with puzzling (anomalous) phenomena, such as desert varnish, that resist classification as ‘biological’ or ‘nonbiological’. Ó 2007 Elsevier Ltd.. (shrink)

This essay focuses on the relationship within western humanism between attitudes toward textual interpretation and views of the human self in an attempt to unsettle the dichotomy between humanist and antihumanist approaches to the past. It has three main parts. First, it uses Umberto Eco's recent reflections on the limits of interpretation to explore current debates about the aims of interpretation. In particular, it asks what it means to frame the problem of interpretation specifically as a problem of establishing limits. (...) Given the many possible vocabularies to compare and evaluate competing hermeneutic approaches, what are the implications of adopting one that speaks in terms of limits, of an "in bounds" and an "out of bounds?" Second, the essay draws on the work of Donna Haraway and Stephanie Jed to argue that a discourse about interpretation that seeks to establish the limits of interpretation excludes as out of bounds precisely those methodological strategies that most effectively analyze the mutually sustaining relationship between assumptions about texts and assumptions about selves. Third, the essay explores the relationship between interpretation and subjectivity at one key historical moment to show how to move beyond the strict dichotomy between humanist and antihumanist assumptions. (shrink)

Elymnion, according to Stephanos, was S000983880002084X_inline4 The name occurs in Aristophanes {Peace, 1126) in a context which points to the neighbourhood of Oreos. There is no evidence to connect it immediately with Chalkis. Mela mentions an Echinia near Akanthos: ' inter Strymona et Athon Turris Calarnaea et portus Capru, urbs Acanthos et Echinia.' Confusion of A and X is easy. Thus, even if the first sentence has no ol, the passage gives no safe evidence that these settlers came to Kleonai (...) from Chalkis, or from Euboea. Such a derivation would be hard to reconcile with Thucydides' account of the towns on Akte. If oί is right, cadit quaestio. (shrink)

In recent years, an increasing number of philosophers have come to doubt the viability of the empiricist program of analyzing the concepts of lawhood and causation in terms of nonnomic or noncausal concepts. The central thesis of Carroll's book is that these concepts cannot be so analyzed. Carroll is quite liberal about what he is willing to count as a reductive analysis. He does not identify an analysis with a definition, as traditional empiricists have insisted upon. He is willing to (...) go along with contemporary empiricists who are satisfied that they have an analysis if they can identify necessary conditions or even just a supervenience base. Moreover, he is willing to include concepts with nomic and causal commitments in the supervenience base. Thus Carroll intends his conclusions to encompass all empiricist attempts, no matter how weak, to analyze the concepts of lawhood and causation. (shrink)

This book consists of notes of lectures given by G. E. Moore at Cambridge during the three terms of 1934-35. They were compiled by the editor, Alice Ambrose, who was then Student of Newnham College, and the late Margaret Macdonald, who was then Fellow of Girton College. The lectures contain discussions of some material on which Moore published little or nothing, for example, types and tokens, propositional functions and their relation to common properties and relations, and the objects of false (...) judgements. They also include detailed examinations of the views of a number of Moore's contemporaries, including C. D. Broad, Bertrand Russell, F. P. Ramsey, W. E. Johnson, and John Wisdom. Moreover, the lectures do a nice job of illustrating Moore's general approach to the philosophical enterprise, highlighting his emphasis upon ordinary language and revealing the high standards of clarity and precision that he demanded of himself and others. It is clear, however, that Moore is not so much concerned with formulating philosophical positions as with exploring philosophical problems. This lends a certain lack of focus to the lectures and makes them a bit confusing at times. Nevertheless, the lectures provide valuable insight into the evolution of Moore's later thought about a number of important philosophical problems. (shrink)

Manuel des Études grecques et latines. ParL. Laurand. Fascicule VII.: Métrique, Sciences complémentaires (Critique des textes, Paléographie, Épigraphie, Numismatique, Histoire de la Philologie, Bibliographic, Le Travail philologique): 4e édition, revue et corrigée. Appendices II.-IV.: L'Art oratoire des anciens, L'Enseignement du grec et du latin, Lectures de litterature grecque et latine. Appendice V.: Petit atlas pratique d'histoire grecque et romaine. Paris: Auguste Picard, 1929. - Volume 45 Issue 2.

Ductin is the highest conserved membrane protein yet found in eukaryotes. It is multifunctional, being the subunit c or proteolipid component of the vacuolar H+‐ATPase and at the same time the protein component of a form of gap junction in metazoan animals. Analysis of its structure shows it to be a tandem repeat of two 8‐kDa domains derived from the subunit c of the F0 proton pore from the F1F0 ATPase. Each domain contains two transmembrane α‐helices, which together may form (...) a four‐helix bundle. In both the V‐ATPase and gap junction channel, ductin is probably arranged as a hexamer of subunits forming a central channel of gap junction‐like proportions. The two functions appear to be seggregated by ductin having two orientations in the bilayer. Ductin is also the major component of the mediatophore, a protein complex which may aid in the release of neurotransmitters across the pre‐synaptic membrane. It is also a target for a class of poorly understood viral polypeptides. These polypeptides are small and highly hydrophobic and some have oncogenic activity. Ductin thus appears to be at the crossroads of a number of biological processes. (shrink)