[Brief Therapies : Fundamental concepts]

The so-called Palo Alto school has produced a fundamental work in the comprehension of human communication. Palo Alto school defined the theoretical concepts of brief therapies and the foundations of systemic therapies. First, this article proposes to specify the sociological context in which systemic theories have emerged by differentiating the paradigms of modern and post-modern societies. Second, it defines some keystone concepts in the field of brief therapies : the homeostasis, the positive and negative feedbacks, the changes of level 1 and 2, the identified patient, the paradoxical injunction and the reframing. Finally, it underlines the risks of a misuse of brief therapies. Indeed, on a superficial level, brief therapies could seem very easy to use. In reality, they are based on great amount of theories and require an important professional experience and an in-depth training.