This article on the epistemology of computational models stems from an analysis of the Gaia hypothesis (GH). It begins with James Kirchner’s criticisms of the central computational model of GH: Daisyworld. Among other things, the model has been criticized for being too abstract, describing fictional entities (fictive daisies on an imaginary planet) and trying to answer counterfactual (what-if) questions (how would a planet look like if life had no influence on it?). For these reasons the model has been considered not (...) testable and therefore not legitimate in science, and in any case not very interesting since it explores non actual issues. This criticism implicitly assumes that science should only be involved in the making of models that are ‘‘actual’’ (by opposition to what-if) and ‘‘specific’’ (by opposition to abstract). I challenge both of these criticisms in this article. First by showing that although the testability—understood as the comparison of model output with empirical data—is an important procedure for explanatory models, there are plenty of models that are not testable. The fact that these are not testable (in this restricted sense) has nothing to do with their being ‘‘abstract’’ or ‘‘what-if’’ but with their being predictive models. Secondly, I argue that ‘‘abstract’’ and ‘‘what-if’’ models aim at (respectable) epistemic purposes distinct from those pursued by ‘‘actual and specific models’’. Abstract models are used to propose how-possibly explanation or to pursue theorizing. What-if models are used to attribute causal or explanatory power to a variable of interest. The fact that they aim at different epistemic goals entails that it may not be accurate to consider the choice between different kinds of model as a ‘‘strategy‘‘. (shrink)

The new discipline of exobiology formed from the intertwining of origin of life research with the search for life or its building blocks on other planets, from 1957-1973. The field was inherently highly interdisciplinary, yet it coalesced very quickly and was responsible in its first twenty years for numerous important contributions to twentieth century life science and planetary sciences such as climatology, the study of mass extinctions, etc. NASA played a very important role in catalyzing the rapid consolidation of exobiology, (...) both through research grants and through sponsored meetings that overcame disciplinary boundaries, bringing together scientists from diverse backgrounds. The presence of a handful of prominent senior scientists such as Joshua Lederberg, Melvin Calvin and Norman Horowitz helped gain credibility for exobiology, in the face of criticism and competition from existing life sciences disciplines. Tensions within the exobiology research community and between NASA-funded science and the academic research community are explored, as are such milestones of discipline formation as journals and professional societies. (shrink)

“Astrobiology as science” refers to how astrobiology is characterized and discussed in the philosophy of science.

In this review, we describe some of the central philosophical issues facing origins-of-life research and provide a targeted history of the developments that have led to the multidisciplinary field of origins-of-life studies. We outline these issues and developments to guide researchers and students from all fields. With respect to philosophy, we provide brief summaries of debates with respect to (1) definitions (or theories) of life, what life is and how research should be conducted in the absence of an accepted theory (...) of life, (2) the distinctions between synthetic, historical, and universal projects in origins-of-life studies, issues with strategies for inferring the origins of life, such as (3) the nature of the first living entities (the “bottom up” approach) and (4) how to infer the nature of the last universal common ancestor (the “top down” approach), and (5) the status of origins of life as a science. Each of these debates influences the others. Although there are clusters of researchers that agree on some answers to these issues, each of these debates is still open. With respect to history, we outline several independent paths that have led to some of the approaches now prevalent in origins-of-life studies. These include one path from early views of life through the scientific revolutions brought about by Linnaeus (von Linn.), Wöhler, Miller, and others. In this approach, new theories, tools, and evidence guide new thoughts about the nature of life and its origin.We also describe another family of paths motivated by a” circularity” approach to life, which is guided by such thinkers as Maturana & Varela, Gánti, Rosen, and others. These views echo ideas developed by Kant and Aristotle, though they do so using modern science in ways that produce exciting avenues of investigation. By exploring the history of these ideas, we can see how many of the issues that currently interest us have been guided by the contexts in which the ideas were developed. The disciplinary backgrounds of each of these scholars has influenced the questions they sought to answer, the experiments they envisioned, and the kinds of data they collected. We conclude by encouraging scientists and scholars in the humanities and social sciences to explore ways in which they can interact to provide a deeper understanding of the conceptual assumptions, structure, and history of origins-of-life research. This may be useful to help frame future research agendas and bring awareness to the multifaceted issues facing this challenging scientific question. (shrink)

Here I pursue a deconstructive reading of astrobiology, the emerging science dedicated to a double quest: solving the mystery of life's origin and discovering life beyond Earth. Astrobiology, I argue, is organized as a response to the aporetic formulation assumed by the origin of life in modern molecular biology, where (as Derrida's argues in Life Death) it becomes the origin of textuality. Because all Earth life shares a single genetic code, astrobiologists are seeking a second; hoping that a sort of (...) multi-planetary comparative genomics may reveal the secret to life's origin. But the aporia repeats in the figure of the biosignature, the trace of life. (shrink)

It is a commonplace in the history of science that reputations of scientists play important roles in the stories of scientific knowledge. I argue that to fully understand these roles we should see reputations as produced by communicative acts, consider how reputations become known about, and study the factors influencing such processes. I reapply James Secord's ‘knowledge-in-transit’ approach; in addition to scientific knowledge, I also examine how ‘biographical knowledge’ of individuals is constructed through communications and shaped by communicative contexts. My (...) case study is Carl Sagan, widely discussed – amongst scientists, media professionals and publics – for his skill as a charismatic popularizer, his perceived arrogance, his political activism, and his debated merit as a researcher. By examining how aspects of Sagan's reputation circulated alongside his scientific work – rather than existing as a static context for his scientific work – I show how different forms of knowledge (biographical and scientific) influence each other as they circulate. (shrink)

All life on Earth shares the same ancestor, the most primitive form of life that arose, in still unknown circumstances, more than 3.5 billion years ago. At least this is what is commonly assumed. Astrobiologists have revisited this assumption and advanced the hypothesis of the existence of a “shadow biosphere” on Earth: a parallel tree of life whose instances, being different at the molecular level to the kind of life we are used to, would remain hidden from view. In this (...) paper, I take the emergence of the so-called shadow biosphere hypothesis and the controversial discovery of GFAJ-1, a microbe thriving in the arsenic-rich waters of Mono Lake, as an entry point to look into the strategic role of non-knowledge claims. I juxtapose the Latourian black-box, that is, those undiscussed technoscientific artifacts that are taken for granted in scientific practice, with the shadowy nature of non-knowledge claims in order to pay closer attention to the contingent, active, performative, and always social nature of the making of what is unknown. I conclude this paper by claiming that in the negotiation of what is unknown, emerging disciplines position themselves within the larger scientific community. (shrink)

This paper examines the roles played by instruments and their associated practices in the development of the field of planetary geology. Specifically, remote sensing instruments and the images produced by instrument users are discussed. It is argued that through these instruments and images the first two generations of planetary geologists were able to 'domesticate' the planets and make them suitable for geological study. But this was not a straightforward process. The instruments themselves had to be 'domesticated' as geological tools, and (...) the definition of 'geologist' had to be broadened to include such tools and extraterrestrial terrains. This paper looks first at the first generation of planetary geologists associated with the mapping and study of the Moon in the 1960s and 70s, then focuses on the second generation that emerged during the exploration and mapping of Mars. Within this second section, the paper focuses on the introduction of one new type of instrument -- the orbiting infrared spectrometer, and examines three such instruments and the visual claims made with its images. (shrink)

If everything is in permanent change, can the Universe itself be fundamentally passive? Answering this question requires a clear concept of ‘activity.’ The nature of ‘action’ is a central and unsolved philosophical problem. Actions play a crucial role in the way we conceive of ourselves, life and the Universe, and the value we put on these. In four decades of research on solar activity, we found that activity is not a mere occurrence but a genuine activity of the Sun, initiated (...) globally by the Sun using quantum processes as tools that generates suitable primary mass flows locally in the solar core that are capable of producing a working dynamo. We argue that solar activity is initiated by biological causes given by the fundamental principle of biology. This universal activity is the basis of our life instinct and of logic too. (shrink)

This article on the epistemology of computational models stems from an analysis of the Gaïa hypothesis. It begins with James Kirchner’s criticisms of the central computational model of GH: Daisyworld. Among other things, the model has been criticized for being too abstract, describing fictional entities and trying to answer counterfactual questions. For these reasons the model has been considered not testable and therefore not legitimate in science, and in any case not very interesting since it explores non actual issues. This (...) criticism implicitly assumes that science should only be involved in the making of models that are “actual” and “specific”. I challenge both of these criticisms in this article. First by showing that although the testability—understood as the comparison of model output with empirical data—is an important procedure for explanatory models, there are plenty of models that are not testable. The fact that these are not testable has nothing to do with their being “abstract” or “what-if” but with their being predictive models. Secondly, I argue that “abstract” and “what-if” models aim at epistemic purposes distinct from those pursued by “actual and specific models”. Abstract models are used to propose how-possibly explanation or to pursue theorizing. What-if models are used to attribute causal or explanatory power to a variable of interest. The fact that they aim at different epistemic goals entails that it may not be accurate to consider the choice between different kinds of model as a “strategy“. (shrink)