This paper takes Udo Thiel’s The Early Modern Subject: Self-Consciousness and Personal Identity from Descartes to Hume as an example of a study that aims to provide an account of a particular philosophical development, and discusses both the methodological requirements and the philosophical commitments connected with this ambition. In a first step, I distinguish between two fundamentally different ways of thinking about philosophical development, viz. externalism and internalism with regard to historical developments in philosophy, and I consider two ways of (...) defining the two respective positions. Next, I specify certain methodological decisions that are relevant when writing a study on a particular philosophical development, and I characterize Udo Thiel’s book with respect to them. While no definitive position is taken with regard to the issues raised, the paper does advocate a reflective approach to them. (shrink)