identified a problem which he believed plagued modern life.

Mauvaise Foi, literally "bad faith"

Bad faith occurs when we lie to ourselves in order to spare ourselves short term pain,

but thereby suffer from long term psychological impoverishment.

We force ourselves to believe something which we're not really convinced by, because it's easier.

In particular, Sartre believe that what we constantly lie to ourselves about is that we don't have other options.

We always do, but find it curiously more reassuring to say we don't. It lets us off the hook.

Bad faith often happens around work.

Sartre describes a waiter who tells himself he's just a waiter. It's his lot in life, his destiny.

He tells himself that he had no choice, that he has to keep on at it because he needs the money.

But it's not true, insists Sartre, we are all free.

There are scary, almost sickening moments of what Sartre calls Negative Ecstasy,

which might come late at night, when we realize that we are in fact far more free than we ever say we are.

That we could throw in the job, go and live in the woods, or reinvent ourselves.

It can be harrowing, because we have to acknowledge that we may be wasting our lives and that in the end this is our own fault,

however much at other times we are tempted to blame circumstances or other people.

But we then typically suppress this insight. The next day we force ourselves to believe in what we're doing.

The price is that we close off the opportunities for changing and improving our lives

We forget, Sartre Says, that 'Being precedes essence'

That is, who we are can't be pinned down to one particular job or relationship.

Our being is much bigger.

It embraces in Sartre's words "all the things we are at present not, but could possibly become".

In bad faith we keep those possibilities out of our minds, we tell ourselves that the way we are at the moment is the only way we can be,

so bad faith closes down on the options of freedom.

Sartre detected bad faith as a feature of many unhappy relationships.

He describes its origins in early dates when a couple secretly realise that they are not at all compatible,

but then force themselves to believe that they can be happy together.

In Sartre's example, a woman wants to be loved for her mind and can't bear to pay attention to her own dark suspicion that her partner is in fact more interested in her body.

Meanwhile the man realises that the woman isn't interested in him sexually, but keeps telling himself that "really she must be".

They both lie to themselves and that's why they end up together and unhappy.

Bad faith will lead them to throw the blame on each other saying it's the other's coldness or lack of sophistication that's the problem,

when really it's their own doing.

Sartre didn't see bad faith as a surprising or unusual problem. It's a natural outcome of how our minds work.

He didn't want us to feel bad. He just wanted to remind us to be as free as we really are.