More specifically, the
Sartrean concept of bad faith refers to a person acting in a way that is untrue to their basic nature.
Sartre divided the
human into two
aspects:
facticity and
transcendence. Facticity is the historical element of one's life. It is the things you've done, which can never be changed and which indelibly affect others' perceptions of you. Transcendence is your ability to change, to imagine things as different and make them so through an act of
will. In
Being and Nothingness, facticity is the "being" and transcendence is the "nothingness" (because, as the free and mutable part of a person, it can never be pinned down or given a definite nature of its own).
At any time, who you are is defined by both parts of you. No matter how much
facticity you have behind you, it's never right to
abdicate responsibility -- for example, to say
I can't help beating her. I'm just a violent person.. You can always change things, even if only gradually and with great effort. As long as you live, you have
freedom and choice. On the other hand, you can never change in a moment. If you suddenly choose to give up violence, you are still a violent person because of the things you've done in the past, facts you can't change. The decision, made by
ineffable transcendence, must be put into
practice before it can be considered part of you. This is partially because the decision of a moment can easily be strangled by ingrained habit. More significantly, it's because Sartre saw personality as being
constructed by our interactions with others. Therefore, in order for something to become part of you it must be shown to and recognized by other human beings (this isn't a
communalist philosophy that demeans the
individual; it's based on the idea that we can only properly see ourselves when we are reflected by an Other).
When either part of your nature is ignored, you are living in bad faith. Bad faith can be reached either by pretending that you have no ability to change, and are trapped by your
habits, or by pretending that a decision to change is the same as having neutralized your past.
Cognitive behavioral therapy can be seen as a set of skills for turning
transcendence into
facticity.