Before psychology became a science it had a difficulty to overcome: to demonstrate that it could even be a science. That has been the basis of its abiding neurosis—anxiety over not being considered scientific, which prompted the diagnosis of “physics envy.” In the late 18th century Kant determined that psychology, defined as the analysis of mind through introspection, could not be an experimental science (Hergenhahn and Henley, 2014). Since it was not a physical thing, mind could not be investigated objectively. Introspection was no aid since the mind would not hold still for analysis. Additionally, the introspective process itself would influence the mind interfering with its independent observation. Furthermore, and perhaps most sig­nificant to psychology’s struggle to prove itself, a scientific subject matter required precise mathematical applications and mind was immeasurable. What it means to be a science, and whether psychology can lay claim to such status, is the topic of this chapter. We will consider the following:

• What does it mean to be scientific and when did humans become scientific?
• Scientific thinking versus common sense.
• Physics envy and psychology as a science.
• Natural kinds versus human kinds.
• A question of ethics.