The purpose of this essay is to show that the issue of "underdevelopment" not only raises one of the most basic and oldest problems of philosophy, namely the relationship between the spiritual and the material, but also helps positively to reformulate it. For, on closer examination, it will appear that the striking aspect of underdevelopment is that it constitutes a glaring symptom of a characteristic disturbance or maladjustment. By its strangeness and distortion, it displays a unique and unexpected tension between the spiritual and the material. Indeed, we cannot discard the possibility that the link between the spiritual and the material is likely to be better exposed in a situation of maladjustment than in one of fusion. Besides, this method of studying tension in order to observe the connection between the mental and the physical is not something new in philosophy. Bergson, Freud, and James, to mention but a few, had recourse to it.