Neurosurgery is a topic that evokes many hopes and fears at the same time. One of these fears is concerned with the worry about losing one's identity. Taking this concern seriously, the article deals with the question: Can the concept of ‘personal identity’ be used successfully in normative considerations concerning neurosurgery? This question will be answered in three steps. First, a short introduction to the philosophical debate about personal identity is given. Second, a new theory of personal identity is presented. (...) This theory has two components. On the one hand, it explains the phenomenon of human existence through time. On the other hand, it demonstrates the normative concept of personal identity. The final step proves the explanatory power of the theory on the basis of a practical example, namely deep brain stimulation. It will be shown that personal identity alters quite easily, whereas human persistence is rather stable. The distinction between both concepts finally serves to develop a terminology that is able to structure normative debates very effectively. (shrink)

Traditionally, this puzzle has been solved in various ways. Aristotle, for example, distinguished between “accidental” and “essential” changes. Accidental changes are ones that don't result in a change in an objects' identity after the change, such as when a house is painted, or one's hair turns gray, etc. Aristotle thought of these as changes in the accidental properties of a thing. Essential changes, by contrast, are those which don't preserve the identity of the object when it changes, such as when (...) a house burns to the ground and becomes ashes, or when someone dies. Armed with these distinctions, Aristotle would then say that, in the case of accidental changes, (1) and (2) are both false—a changing thing can really change one of its “accidental properties” and yet literally remain one and the same thing before and after the change. (shrink)