He has done much interdisciplinary work on the interface of linguistics and philosophy—in particular on the philosophical foundations of Noam Chomsky's theory of generative linguistics and on the foundations of the theory of meaning in linguistic semantics. He has worked on the application of analytic philosophy of language to topics in epistemology, metaphysics, and logic, among other areas.
Ludlow has also established a research program outside of philosophy and linguistics. Here, his research areas include conceptual issues in cyberspace, particularly questions about cyber-rights and the emergence of laws and governance structures in and for virtual communities. MTV.com has described Ludlow as one of the 10 most influential video game players of all time, in part due to his role in showing how video game companies can be challenged as part of the gameplay. In recent years Ludlow has written nonacademic essays on hacktivist culture and related phenomena such as Wikileaks.