For millennia, philosophers have debated what makes an entity a person. Initially, rationality was seen as the defining characteristic of what made one a human. If an entity could engage in rational thought, then it was considered a human. This notion of rationality was often limited to men of European descent though. It was not until the 1 nineteenth century when thinkers such as Friedrich Nietzsche questioned this model, thus opening the way for new theories of personhood to emerge.