Overview
In the philosophy of existentialism, bad faith (mauvaise foi) is the psychological phenomenon whereby individuals act inauthentically, by yielding to the external pressures of society to adopt false values and disown their innate freedom as sentient human beings. Bad faith also derives from the related concepts of self-deception and ressentiment.
Freedom and choice
A critical claim in existentialist thought is that individuals are always free to make choices and guide their lives towards their own chosen goal or "project". This claim suggests that individuals cannot escape this freedom, even in overwhelming circumstances. For instance, even an empire's colonized victims possess choices: to submit to rule, to negotiate, to commit suicide, to resist nonviolently, or to counter-attack.
Although external circumstances may limit individuals (this limitation from the outside is called facticity), they cannot force a person to follow one of the remaining courses over another. In this sense the individual still has some freedom of choice. For this reason, an individual may choose in anguish, fully aware that this will have consequences. For Sartre, to claim that one amongst many conscious possibilities takes undeniable precedence (for instance, "I cannot risk my life, because I must support my family") is to assume the role of an object in the world, not a free agent, but merely at the mercy of circumstance (a being-in-itself that is only its own facticity, i.e., it "is" inside itself, and acts there as a limitation). For Sartre, this attitude is manifestly self-deceiving.
Intentional consciousness and freedom
According to this philosophy, humans are always aware that they are more than what they are aware of. In other words, they are not whatever they are aware of. In this sense, humans cannot be defined as "intentional objects" of consciousness that includes the restrictions imposed by facticity, personal history, character, bodies, or objective responsibility. Thus, as Sartre often repeated, "Human reality is what it is not, and it is not what it is." An example of what he means is being a doctor but wishing to "transcend" that to become a pig farmer. One is who one is not: a pig farmer, not who one is, a doctor.
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