I discuss Aristotle's treatment of essence and definition in Metaphysics VII.4. I argue that it is coherent and perfectly in accord with its broader context. His discussion in VII.4 offers, on the one hand, minimal criteria for what counts as definition and essence for whatever kind of object, but also, on the other hand, stronger criteria for a primary sort of definition and essence—and thereby it serves the interest of book VII in pointing to the explanatory power of the essence (...) of composite substances. (shrink)

I discuss a short string of five sentences in Metaphysics V.5, 1015b6-9 relating demonstration to necessity. My proposal is that Aristotle focuses his attention on the demonstration as a demonstration. Other interpretations reduce the necessity in question to the modality of the component sentences of the demonstrations (the conclusion and the premises). My view does not deny that the modality of the component sentences is important, but takes seriously the idea that a demonstration itself should be understood as necessary—as not (...) capable of being otherwise. A demonstration cannot be different from what it is in the sense that [i] its components cannot be different from what they are, [ii] its components must be related to each other exactly in the way they are related. Demonstrations aim at the fully appropriate explanation of a given explanandum—and each demonstration is individuated by the explanandum it takes. Thus, the basic idea is that, for the target explanandum that individuates a given demonstration, the premises delivering the fully appropriate explanation cannot be replaces with different ones. I show how this proposal, which explains Aristotle’s language in 1015b6-9 accurately, does not make demonstrations ‘melt down into conditional necessity’, first, because the modality of the component sentences is still importantly involved, second, because the explanatory relation expressed in a demonstration is a necessary fact in the real world, so that the demonstration itself is also necessary (in the way I have explained) inasmuch as it captures that fact. (shrink)

When the costs of acquiring knowledge outweigh the benefits of possessing it, ignorance is rational. In this paper I clarify and explore a related but more neglected phenomenon: cases in which ignorance is motivated by the anticipated costs of possessing knowledge, not acquiring it. The paper has four aims. First, I describe the psychological and social factors underlying this phenomenon of motivated ignorance. Second, I describe those conditions in which it is instrumentally rational. Third, I draw on evidence from the (...) social sciences to argue that this phenomenon of rational motivated ignorance plays an important but often unappreciated role in one of the most socially harmful forms of ignorance today: voter ignorance of societal risks such as climate change. Finally, I consider how to address the high social costs associated with rational motivated ignorance. (shrink)

This paper argues that Aristotle’s Metaphysics Z.3 deploys a reductio against the claim that ‘substances underlie by being the subjects of predication’, in order to demonstrate the need for a new explanation of how substances underlie. Z.13 and H.1 corroborate this reading: both allude to an argument originally contained in Z.3, but now lost from our text, that form, matter and compound ‘underlie’ in different ways. This helps explain some of Z’s peculiarities—and it avoids committing Aristotle to self-contradiction about whether (...) matter is substance, a claim denied in the reductio but endorsed elsewhere. (shrink)

Las Sentencias de Porfirio, que constituyen un compendio de las Enéadas de Plotino, incluyen una revisión del locus vexatus de platonismo del siglo III, que tiene su origen en la interpretación de un controvertido pasaje del Timeo, 39e. Revisaremos los antecedentes de Porfirio, bajo la influencia de Longino, y la polémica suscitada con Plotino y Amelio a su llegada a Roma. Su posterior "retractación" le lleva a aceptar que la Inteligencia se identifica con la multiplicidad de los inteligibles que intelige. (...) La Inteligencia es sujeto inteligente y, al mismo tiempo, objeto inteligido, es decir, ejerce sobre sí misma su propia actividad intelectual. Nuestro análisis tratará de poner en conexión textos de las Sentencias, particularmente provenientes de la 43, con pasajes extraídos de los tratados plotinianos. The Sentences of Porphyry, that are a compendium of the Plotinus Enneads, include a review of the locus vexatus of the third century Platonism, which has its origin in the interpretation of a controversial passage of Timaeus, 39e. We will review the historical causes of Porphyry, under Longinus influence, and the controversy with Amelius and Plotinus on his arrival in Rome. His subsequent "retraction" takes him to accept that Intellect is identified with the multiplicity of intellections that intelligizes. Intellect is an intelligent subject and, at the same time, an intelligized object, that is, itself exerts on its own intellectual activity. Our analysis will seek to bring together texts of the Sentences, particularly from the 43, with excerpts from Plotinus treaties. (shrink)

Commentary on Aristotle's Metaphysics Lambda. It accompanies the translation of Aristotle's Metaphysics Lambda into Portuguese in the same volume of the journal.