John R. Welch

Saint Louis University - Madrid Campus
  •  11
    Human decisions are conditioned by formidable uncertainty. The standard resource for dealing rationally with uncertainty is the mathematical concept of probability. The probability calculus is well-known, but since the numerical demands for applying it cannot usually be met, it is not widely applicable. By contrast, the concept of plausibility is widely applicable, but it is little known. This book relies on a generalized concept of plausibility whose strength is its adaptability. The adaptabili…Read more
  •  26
    Rebooting the new evidence scholarship
    International Journal of Evidence and Proof 24 (4): 351-373. 2020.
    The new evidence scholarship addresses three distinct approaches: legal probabilism, Bayesian decision theory and relative plausibility theory. Each has major insights to offer, but none seems satisfactory as it stands. This paper proposes that relative plausibility theory be modified in two substantial ways. The first is by defining its key concept of plausibility, hitherto treated as primitive, by generalising the standard axioms of probability. The second is by complementing the descript…Read more
  •  13
    Commentary on “The strategic formulation of abductive arguments in everyday reasoning”
    Argumentation, Objectivity, and Bias: Proceedings of the 11th International Conference of the Ontario Society for the Study of Argumentation (OSSA). 2016.
    Henrike Jansen’s “The strategic formulation of abductive arguments in everyday reasoning” insightfully explores the terrain of abductive argumentation. The purpose of this note is to continue the exploration along lines marked out by her paper. This further exploration proceeds in two stages. Section 2 of the paper addresses the nature of abductive inference by distinguishing two types of abduction, identifying some of abduction’s formal and nonformal properties, and relating abduction to enthym…Read more
  •  41
    Credence for conclusions: a brief for Jeffrey’s rule
    Synthese 197 (5): 2051-2072. 2020.
    Some arguments are good; others are not. How can we tell the difference? This article advances three proposals as a partial answer to this question. The proposals are keyed to arguments conditioned by different degrees of uncertainty: mild, where the argument’s premises are hedged with point-valued probabilities; moderate, where the premises are hedged with interval probabilities; and severe, where the premises are hedged with non-numeric plausibilities such as ‘very likely’ or ‘unconfirmed’. Fo…Read more
  •  50
    Apuntes sobre el pensamiento matemático de Ramón Llull
    Theoria: Revista de Teoría, Historia y Fundamentos de la Ciencia 4 (2): 451-459. 1989.
    This paper attempts to clarify some of the mathematical details of Ramón Llull's combinatorial logic.
  • Reduction: Suiting the Concept to Multiple Tasks
    Dissertation, Boston University Graduate School. 1983.
    Nothing-but claims hold that one sort of entity is ultimately another sort of entity. That the mental is nothing but the physical, that the macroscopic is nothing but the microscopic, and that the prescriptive is nothing but the descriptive are controversial examples. To settle whether one of these claims is true or false, what sort of evidence would one have to have? The dissertation formulates a criterion for culling false nothing-but claims from true by clarifying the concept of ontological r…Read more
  •  60
    Coping with Ethical Uncertainty
    Diametros 53 150-166. 2017.
    Most ethical decisions are conditioned by formidable uncertainty. Decision makers may lack reliable information about relevant facts, the consequences of actions, and the reactions of other people. Resources for dealing with uncertainty are available from standard forms of decision theory, but successful application to decisions under risk requires a great deal of quantitative information: point-valued probabilities of states and point-valued utilities of outcomes. When this information is not a…Read more
  •  34
  •  45
    Other Voices: Readings in Spanish Philosophy (edited book)
    University of Notre Dame Press. 2010.
    Other Voices: Readings in Spanish Philosophy represents high points of nearly two millennia of Spanish philosophy, from first-century thinkers in Roman Hispania to those of the twentieth century. John R. Welch has selected, and in several cases translated, excerpts from the works of thirteen philosophers: Seneca, Quintilian, Isidore of Seville, Ibn Rushd (Averroës), Moses Maimonides, Ramón Llull, Juan Luis Vives, Francisco de Vitoria, Bartolomé de Las Casas, Francisco Suárez, Benito Jerónimo Fei…Read more
  •  166
    Reconstructing Aristotle: The practical syllogism
    Philosophia 21 (1-2): 69-88. 1991.
    This article tackles a number of puzzles related to Aristotle’s practical syllogism, notably the relationship between deliberation and the practical syllogism, the distinction between deliberative and reconstructive practical syllogisms, and the nature of the conclusion of the practical syllogism.
  •  98
    Real-Life Decisions and Decision Theory
    In Sabine Roeser, Rafaela Hillerbrand, Per Sandin & Martin Peterson (eds.), Handbook of Risk Theory, Springer. 2012.
    Some decisions result in cognitive consequences such as information gained and information lost. The focus of this study, however, is decisions with consequences that are partly or completely noncognitive. These decisions are typically referred to as ‘real-life decisions’. According to a common complaint, the challenges of real-life decision making cannot be met by decision theory. This complaint has at least two principal motives. One is the maximizing objection that to require agents to determ…Read more
  •  766
    Llull and Leibniz: The Logic of Discovery
    Catalan Review 4 75-83. 1990.
    Llull and Leibniz both subscribed to conceptual atomism: the belief that the majority of concepts are compounds constructed from a relatively small number of primitive concepts. Llull worked out techniques for finding the logically possible combinations of his primitives, but Leibniz criticized Llull’s execution of these techniques. This article argues that Leibniz was right about things being more complicated than Llull thought but that he was wrong about the details. The paper attempts to corr…Read more
  •  62
    The art and logic of Ramon Llull: A user's guide (review)
    Journal of the History of Philosophy 47 (2). 2009.
    Ramon Llull was acutely aware of Islamic and Jewish divergences from Christian belief. He undertook a quest for "necessary reasons" to show that, where these belief systems diverged, Christian belief is true. Though largely self-taught, Llull managed three stays at the University of Paris. Encounters between the incandescent Mallorcan and academic orthodoxy contributed hugely to Llull's changing conception of necessary reasons. These changes are abundantly documented in Anthony Bonner's The Art …Read more
  •  42
    Conclusions as Hedged Hypotheses
    In Welch John R. (ed.), Argumentation, Objectivity, and Bias, Windsor University Press. 2016.
    How can the objectivity of an argument’s conclusion be determined? To propose an answer, this paper builds on Betz’s view of premises as hedged hypotheses. If an argument’s premises are hedged, its conclusion must be hedged as well. But how? The paper first introduces a two-dimensional critical grid. The grid’s vertical dimension is inductive, reflecting the argument’s downward flow from premises to conclusion. It specifies the inductive probability of the conclusion given the premises. The grid…Read more
  •  89
    New Tools for Theory Choice and Theory Diagosis
    Studies in History and Philosophy of Science Part A 44 (3): 318-329. 2013.
    Theory choice can be approached in at least four ways. One of these calls for the application of decision theory, and this article endorses this approach. But applying standard forms of decision theory imposes an overly demanding standard of numeric information, supposedly satisfied by point-valued utility and probability functions. To ameliorate this difficulty, a version of decision theory that requires merely comparative utilities and plausibilities is proposed. After a brief summary of this …Read more
  •  756
    Cleansing the Doors of Perception: Aristotle on Induction
    In Konstantine Boudouris (ed.), Greek Philosophy and Epistemology, International Association For Greek Philosophy. 2001.
    This chapter has two objectives. The first is to clarify Aristotle’s view of the first principles of the sciences. The second is to stake out a critical position with respect to this view. The paper sketches an alternative to Aristotle’s intuitionism based in part on the use of quantitative inductive logics.
  •  52
    Referential inscrutability: Coming to terms without it
    Southern Journal of Philosophy 22 (2): 263-273. 1984.
    According to Quine, terms of divided reference like 'rabbit' have two sorts of problems: problems of direct and deferred ostension. Hence the reference of these terms is inscrutable. This article holds that the problems of deferred ostension can be handled by Goodman's theory of projection, and that the problems of direct ostension turn out to be pedestrian problems of signs.
  •  19
    La antiteoría y la filosofía del Renacimiento
    Cuadernos Salmantinos de Filosofía 20 173-178. 1993.
    This article defends the philosophy of the Renaissance against a critique by Ortega y Gasset. Renaissance philosophy, it is argued, was a rebirth of the Hellenistic and Roman conviction that theory should not be pursued for its own sake; rather, it should be kept on a short leash controlled by practical ends. This Renaissance view is a precursor to the contemporary anti-theory of thinkers like Aranguren, Toulmin, and Williams.
  •  133
    Two Types of Moral Dilemma
    In Matti Häyry & Tuija Takala (eds.), The Future of Value Inquiry, Rodopi. 2001.
    This chapter identifies two types of moral dilemma. The first type is described as ethical clash: whether affirmative action is just or unjust, for example, or whether withholding information from an inquisitive relative is honest or dishonest. In these cases the dilemma takes the form of conflict between an ethical predicate and its complement. The second type of moral dilemma is ethical overlap. Instead of a clash between a single predicate and its complement, here two or more predicates apply…Read more
  •  105
    Decision theory and cognitive choice
    European Journal for Philosophy of Science 1 (2): 147-172. 2011.
    The focus of this study is cognitive choice: the selection of one cognitive option (a hypothesis, a theory, or an axiom, for instance) rather than another. The study proposes that cognitive choice should be based on the plausibilities of states posited by rival cognitive options and the utilities of these options' information outcomes. The proposal introduces a form of decision theory that is novel because comparative; it permits many choices among cognitive options to be based on merely compara…Read more
  •  58
    Plausibilistic coherence
    Synthese 191 (10): 2239-2253. 2014.
    Why should coherence be an epistemic desideratum? One response is that coherence is truth-conducive: mutually coherent propositions are more likely to be true, ceteris paribus, than mutually incoherent ones. But some sets of propositions are more coherent, while others are less so. How could coherence be measured? Probabilistic measures of coherence exist; some are identical to probabilistic measures of confirmation, while others are extensions of such measures. Probabilistic measures of coheren…Read more
  •  18
    Javier Muguerza’s Ethics and Perplexity makes a highly original contribution to the debate over dialogical reason. The work opens with a letter that establishes a parallel between Ethics and Perplexity and Maimonides’s classic Guide of the Perplexed. It concludes with an interview that repeatedly strikes sparks on Spanish philosophy’s emergence from its “long quarantine,” as Muguerza puts it. These informal pieces—witty, informative, conversational—orbit the nucleus of the work: a formidable cri…Read more
  •  583
    Singular Analogy and Quantitative Inductive Logics
    Theoria: Revista de Teoría, Historia y Fundamentos de la Ciencia 14 (2): 207-247. 1999.
    The paper explores the handling of singular analogy in quantitative inductive logics. It concentrates on two analogical patterns coextensive with the traditional argument from analogy: perfect and imperfect analogy. Each is examined within Carnap’s λ-continuum, Carnap’s and Stegmüller’s λ-η continuum, Carnap’s Basic System, Hintikka’s α-λ continuum, and Hintikka’s and Niiniluoto’s K-dimensional system. Itis argued that these logics handle perfect analogies with ease, and that imperfect analogies…Read more
  •  37
    Analogy in Ethics: Pragmatics and Semantics
    In Paul Weingartner, Gerhard Schurz & Georg Dorn (eds.), The Role of Pragmatics in Contemporary Philosophy, Die Österreichische Ludwig Wittgenstein Gesellschaft. 1997.
    This chapter explores arguments from analogy containing ethical predicates like 'just', 'courageous', and 'honest'. The approach is Wittgensteinian in a double sense. The role of paradigm cases in ethical discourse is emphasized, first of all, and the inductive logics to be employed spring from Wittgenstein's remarks on probability (1922). Although these logics rely on a semantic concept of range, they yield results for the ethical problems treated here only if grounded in certain kinds of pragm…Read more
  •  19
    Reyes Mate's Memory of the West looks back in order to look forward. It is a sustained reflection on the great disillusion Europe experienced after World War I. Europeans understood that bombs had buried the Enlightenment. They knew that, to avoid catastrophe, they had to think anew. The catastrophe came, but Cohen, Benjamin, Kafka, and Rosenzweig had sounded the warning.
  •  112
    Vagueness and Inductive Molding
    Synthese 154 (1): 147-172. 2007.
    Vagueness is epistemic, according to some. Vagueness is ontological, according to others. This article deploys what I take to be a compromise position. Predicates are coined in specific contexts for specific purposes, but these limited practices do not automatically fix the extensions of predicates over the domain of all objects. The linguistic community using the predicate has rarely considered, much less decided, all questions that might arise about the predicate’s extension. To this extent, t…Read more
  •  43
    Gruesome predicates
    In Roberto Festa, Atocha Aliseda & Jeanne Peijnenburg (eds.), Confirmation, Empirical Progress, and Truth Approximation, Rodopi. pp. 129-137. 2005.
    This chapter examines gruesome predicates, the most notorious of which is 'grue'. It proceeds by extending the analysis of Theo A. F. Kuipers' From Instrumentalism to Constructive Realism in three directions. It proposes an amplified typology of grue problems, first of all, and argues that one such problem is the root of the rest. Second, it suggests a solution to this root problem influenced by Kuipers' Bayesian solution to a related problem. Finally, it expands the class of gruesome predicates…Read more
  •  5
    Responsabilidad colectiva y reduccionismo
    Pensamiento 48 (189/192). 1992.
    This is the Spanish translation of "Corporate Agency and Reduction," The Philosophical Quarterly 39 (1989), 409–424.
  •  7
    Hacia una lógica de analogía
    Revista Latinoamericana de Filosofia 20 (1): 161-167. 1994.
    How do we distinguish good and bad analogies? Luis A. Camacho proposed that false analogies be construed as false material conditionals. This article offers a counter-proposal: analogies of all sorts can be understood as singular inductive inferences. For the sake of simplicity, this proposal is illustrated with reference to Carnap's favorite inductive method c*.