The concept of cognitive engineering is not fixed and unequivocal, but in its various expressions are found certain common features. The fluidity of the idea is not surprising since its arrival is relatively recent, and its formation into something more determinate awaits the outcome of its practices as all disciplines do. There is probably a consensus on what constitutes cognition or cognitive behavior — reasoning, remembering, planning, etc. However, agreeing on what we mean by engineering — particularly of cognition or cognitive behavior — is not so straightforward. One of the reasons that this is so is that engineering is not adequately understood in its relationship with science, and this has perhaps implications for how both science and engineering are understood. The question as it affects technology and engineering is addressed, for example, by the aeronautical engineer Vincenti (1990).