The Popperian epistemology underlying Levelt's commentary and other aspects of contemporary psychology has limited application and, in particular, does not apply to the creation or development of theory, the main goal of MacKay . This is relevant to Levelt's questions, “What has changed?” and “What is the harvest?”: From a non-Popperian perspective, both changes and harvest are greater than Levelt's commentary would suggest and carry implications for the field at large.