Alex LeBrun

Hilary Putnam (1975, 2012) believed that mathematical claims are objectively true but that there are no mathematical objects. There are some worries with Putnam’s position. First, it seems inconsistent with the conclusion of the so-called Quine-Putnam indispensability argument: that there are mathematical objects. Second, it seems inconsistent to affirm that 2+2=4 is objectively true but deny that there are numbers. Here, I resolve both of these seeming inconsistencies. I present a novel interpretation of Putnam’s indispensability argument that departs radically from the received version. And then I extract a theory of ontological commitment from close examination of Putnam’s comments.

The literature on theoretical equivalence in philosophy of physics is replete with physical theories that look quite different but are purportedly equivalent. Plausibly, there might exist a pair of equivalent theories that look different insofar as they existentially quantify over different entities. However, given the preeminence of the quantificational theory of ontological commitment, which tells us to look to quantified entities to inform ontology, such a pair of theories seems to be a problem. In this paper, I argue that there is no good way out of the problem, and I reject the quantificational theory of ontological commitment. .

Generative AI is set to transform digital advertising, which remains a revenue juggernaut for much of the internet. In the current model, advertisers use personal data to target users with pre-made content. But with generative AI systems, they will soon be able to create novel advertisements, tailored in real time using individual behavioral and demographic profiles. Early studies suggest that these AI-generated, hyper-personalized ads are significantly more persuasive than traditional ones---even with today’s relatively limited models. As the technology advances, such ads are likely to become the dominant form of digital persuasion. I argue that this development threatens to undermine longstanding constraints that help keep advertising roughly honest. In particular, generative systems can learn to exploit users’ epistemic blind spots---areas where they are especially prone to believe false or misleading claims. While this poses familiar risks in commercial contexts, the stakes are even higher in political advertising, where personalized generative content may produce fragmented "political underworlds" and new forms of targeted propagandizing. I conclude by assessing both technological and regulatory options for mitigating these risks.

Philosophers sometimes give arguments that presuppose the following principle: two theories can fail to be empirically equivalent on the sole basis that they present different “thick” metaphysical pictures of the world. Recently, a version of this principle has been invoked to respond to the argument that composite objects are dispensable to our best scientific theories. This response claims that our empirical evidence distinguishes between ordinary and composite-free theories, and it empirically favors the ordinary ones. In this paper, I ask whether this response to the dispensability argument is tenable. I claim that it is not. This is because it presupposes an indefensible thesis about when two empirical consequences are distinct or the same. My argument provides some insight into what our empirical consequences are, and I conclude that empirical evidence is radically metaphysically neutral. This gives us some insight into the significant content of our scientific theories—the content that a scientific realist is committed to—and I show how this insight relates to questions about theoretical equivalence more broadly.