Here you will find PDFs of my published and forthcoming research. Please cite the published versions.

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Journal Articles

Does Seneca entirely reject the utility of dialectical study for moral improvement? No, I argue here. Focusing on Letter 87, I propose that Seneca raises and disarms objections to formal Stoic arguments in order to help moral progressors avoid backsliding and advance towards ethical knowledge. I trace this method back to Chrysippus and show that reading Letter 87 in this Chrysippean framework yields a satisfying explanation of its otherwise puzzling features.

This paper examines an ancient debate over the rationality of perception. What leads the Stoics to affirm, and the Epicureans to deny, that to form a sense- impression is an activity of reason? The answer, we argue, lies in a disagreement over what is required for epistemic success. For the Stoics, epistemic success consists in believing the right propositions, and only rational states, in virtue of their predicational structure, put us in touch with propositions. Since they identify some sense-impressions as criteria of truth and thus as the basis for epistemic success, the Stoics maintain that sense-impressions must be rational. The Epicureans agree with the Stoics that sense-impressions function as criteria of truth, and also agree broadly on what it means for a state to be rational, but deny that sense-impressions are rational because (1) they think that epistemic success must be supported by a state that is necessarily error-free and (2) accept that rational states can be false. In reconstructing this debate, we refine the standard interpretation of the fundamental difference between Epicurean and Stoic epistemology and also develop parallels with epistemological debates today. One upshot is a more nuanced appreciation of the merits of Epicurean epistemology vis-à-vis the Stoics.

This paper examines some neglected Chrysippean fragments on insecure apprehension (κατάληψις). First, I present Chrysippus’ account of how non-Sages can begin to fortify their insecure apprehension and upgrade it into knowledge (ἐπιστήμη). Next, I reconstruct Chrysippus’ explanation of how sophisms and counter-arguments lead one to abandon one’s insecure apprehension. One such counter-argument originates in the sceptical Academy and targets the Stoic claim that insecure apprehension can be acquired on the basis of custom (συνήθεια). I show how Chrysippus could defend the possibility of custom-based apprehension, while also denying that there is custom-based knowledge.

The early Stoics diagnose vicious agents with various psychological diseases, e.g. love of money and love of wine. Such diseases are characterised as false evaluative opinions that lead the agent to form emotional impulses for certain objects, e.g. money and wine. Scholars have therefore analysed psychological diseases simply as dispositions for assent. This interpretation is incomplete, I argue, and should be augmented with the claim that psychological disease also affects what kind of action-guiding impressions are created prior to giving assent. This proposal respects the Stoic insistence that impression-formation, no less than assent, is an activity of reason. Insofar as the wine-lover’s reason is corrupted in a different way from the money-lover’s, the two vicious agents will form different action-guiding impressions when faced with similar stimuli. Here I juxtapose the Stoic account of expertise, on which experts form more precise action-guiding impressions compared to the amateur, in virtue of possessing a system of grasps (katalēpseis). So expertise enhances, whereas psychological disease degrades, the representational fidelity of the impressions that prefigure action. With these commitments, the Stoics can be seen to offer a nuanced and principled theory of cognitive penetration and to anticipate some recent proposals in epistemology and cognitive science.

One Stoic response to the skeptical indistinguishability argument is that it fails to account for expertise: the Stoics allow that while two similar objects create indistinguishable appearances in the amateur, this is not true of the expert, whose appearances succeed in discriminating the pair. This paper re-examines the motivations for this Stoic response, and argues that it reveals the Stoic claim that, in generating a kataleptic appearance, the perceiver’s mind is active, insofar as it applies concepts matching the perceptual stimulus. I argue that this claim is reflected in the Stoic definition of the kataleptic appearance, and that it respects their more general account of mental representation. I further suggest that, in attributing some activity to the mind in creating each kataleptic appearance, and in claiming that the expert’s mind allows her to form more kataleptic appearances than the amateur, the Stoics draw inspiration from the wax tablet model in Plato’s Theaetetus (190e–196d), where Socrates distinguishes the wise from the ignorant on the basis of how well they match sensory input with its appropriate mental ‘seal’ (σφραγίς).

We argue that the extant evidence for Stoic logic provides all the elements required for a variable-free theory of multiple generality, including a number of remarkably modern features that straddle logic and semantics, such as the understanding of one- and two-place predicates as functions, the canonical formulation of universals as quantified conditionals, a straightforward relation between elements of propositional and first-order logic, and the roles of anaphora and rigid order in the regimented sentences that express multiply general propositions. We consider and reinterpret some ancient texts that have been neglected in the context of Stoic universal and existential propositions and offer new explanations of some puzzling features in Stoic logic. Our results confirm that Stoic logic surpasses Aristotle’s with regard to multiple generality, and are a reminder that focusing on multiple generality through the lens of Frege-inspired variable-binding quantifier theory may hamper our understanding and appreciation of pre-Fregean theories of multiple generality.

Here I propose an interpretation of the ancient Stoic psychological theory on which (i) the concepts that an adult human possesses affect the content of the perceptual impressions (φαντασίαι αἰσθητικαί) she forms, and (ii) the content of such impressions is exhausted by an ‘assertible’ (ἀξίωμα) of suitable complexity. What leads the Stoics to accept (i) and (ii), I argue, is their theory of assent and belief formation, which requires that the perceptual impression communicate information suitable to serve as the content of belief. In arguing for (i), I reject a rival interpretation on which conceptualization occurs subsequently to the formation of a perceptual impression. In arguing for (ii), I deny that perceptual impressions have two kinds of content: one formulated in an assertible, the other sensory, featuring independently of this assertible. I explore the implications of (i) and (ii) for the Stoic theory of emotions, expertise, and rationality, and argue that they shed new light on the workings of impression, assent, and belief.

This paper offers a new defense of the externalist interpretation of the kataleptic impression. My strategy is to situate the kataleptic impression within the larger context of the Stoic account of expertise. I argue that, given mastery in recognizing the limitations of her own state of mind, the subject can restrict her assent to kataleptic impressions, even if they are phenomenologically indistinguishable from those which are not kataleptic.

Chapters in Edited Volumes

A comprehensive overview of Stoic physics, logic, and ethics.

This essay considers how ancient Stoic cosmopolitanism – roughly, the claim all human beings are members of the same “cosmopolis”, or universal city, and so are entitled to moral concern in virtue of possessing reason – informs Stoic thinking about how we ought to treat non-human entities in the environment. First, I will present the Stoic justification for the thesis that there are only rational members of the cosmopolis – and so that moral concern does not extend to any non-human part of the natural world – and explore the foundations of these views in Stoic physics. Next, I will show that, like other anthropocentric theories, Stoic cosmopolitanism allows for environmental preservation and protection of non-human entities, so long as these activities ultimately benefit human beings. However, because the Stoics include the appreciation of natural beauty as a component of the happy life, this justification is not as feeble as it might seem. Humans are naturally set up to contemplate the order and complexity of the universe, and so environmental degradation and species loss, in marring this harmonious system, frustrates the achievement of the human goal. After exploring these facets of Stoic philosophy, and assessing to what extent they might justify environmental conservation, I close with a critical appraisal of Stoic theory – specifically, of the claims that (i) only humans possess reason and (ii) only rational creatures are deserving of moral concern.

Book Reviews