Pavlos Silvestros

Despite the undeniable epistemic progress of developmental biology from the second half of the twentieth century to the present day, there still is widespread disagreement on defining the biological term of ‘development’. This scientific field epistemologically is neither unsuccessful nor immature, thus the persistent lack of agreement on its most central concept raises some important questions: is there any need for an explicit definition of biological development, and if so, what content should the definition have? My central thesis is twofold. First, that current definitions of biological development are conceptually or empirically inadequate. Second, that an explicit definition of biological development is very much needed (a) for the practical purposes of science textbooks, but more importantly is needed (b) epistemically for exposing or overcoming problematic assumptions and for partially guiding scientific research by coding the appropriate assumptions. To support this thesis, initially I will show the deficiencies of the dominant definitions of biological development; and subsequently I will provide two arguments: an Argument from Practical Purposes and an Argument from Epistemic Purposes. Finally, for accommodating practical and epistemic purposes and as a response to the inadequacy of the available definitions of development, I will propose and defend an operational definition of biological development which is aimed to be broader than the received ones, while being more precise and fruitful to conduct empirical research.