"Be yourself" gets handed out as advice so often that nobody stops to ask what it's supposed to fix. It sounds like permission. It's actually a shrug. It assumes there's a finished, honest version of you sitting underneath your life, waiting to be expressed more sincerely — and that the only thing standing between you and it is nerve. Jean-Paul Sartre had a name for the specific way people avoid that confrontation with their own freedom, and it's more useful than "authenticity" precisely because it isn't vague. It's a mechanism you can catch yourself using.
Sartre introduced mauvaise foi — bad faith — in Being and Nothingness (1943). It isn't lying to someone else. It's a lie you tell yourself about how free you are, and it runs in two directions. One is pretending you're more fixed than you are: treating a job, a role, or a habit as if it were your nature rather than something you keep choosing — his famous example is a café waiter whose movements are a fraction too precise, too eager, too waiter-ish, a man performing "waiter" as though it were a solid object rather than a role he re-enters every shift. The other direction is the mirror image: pretending you're more undetermined than you are, staying so open and undecided that you never have to commit to anything a critic could hold against you. Two years later, in the 1946 lecture Existentialism Is a Humanism, Sartre put the underlying claim plainly: we're "condemned to be free" — free not as a treat but as a standing obligation. Bad faith is the general name for the ways people flinch from that obligation without admitting they're flinching.
Here's where "authenticity" as usually deployed actually makes this worse. It tells people the goal is to locate their real self and act from it, which quietly reintroduces the fixed essence Sartre was arguing against — and it can be gamed from either pole of bad faith. You can perform "authenticity" by pointing at a habit and calling it identity: I'm just not a disciplined person, that's not who I am. You can also perform it by pointing at your own indecision and calling it openness: I don't want to commit to a label yet, I'm still finding myself. Both get praised as honest self-knowledge. Both are the same evasion wearing different clothes. Neither one asks the only question that actually distinguishes self-knowledge from self-protection: what, right now, could you choose differently, and are you choosing not to?
This is where Sartre's frame and this book's argument land on the same spot from different directions. The book puts it plainly: being told to "be yourself" assumes "there is a fixed version underneath everything that only needs to be expressed more honestly," and that assumption "removes responsibility" while being "vague enough to hide the real mechanism." It makes the same point about the second pole of bad faith, too — the vagueness move: if your values are treated as some "deep authentic essence," you get to "keep claiming you are still figuring yourself out" indefinitely, because an essence you haven't found yet can't be checked against your actual behaviour. Vagueness like that isn't neutral. It just quietly hands the decision to whatever is easiest that day.
You can watch bad faith operate without any philosophy at all, just by comparing what someone claims against what their week actually contains. Someone can sincerely believe they value health and still arrange their evenings, fridge, and calendar around exhaustion and convenience — not because the value is fake, but because the fixed-self excuse ("I've just never been a morning person") and the vagueness excuse ("I'm working on getting more disciplined, eventually") are both doing the same job: protecting the gap between the claim and the pattern from ever being examined. The value survives untouched precisely because it's never tested against the calendar.
That's the useful version of the test, and it's sharper than asking whether you're "being authentic." Don't ask what feels true to who you are. Ask two narrower questions instead. First: what have you filed under "that's just how I am" that you've actually never seriously tried to change — is that a limit, or an excuse wearing a limit's clothes? Second: what have you kept deliberately vague — a value, a direction, a commitment — specifically so it can't be checked against what you actually do? The first question catches the fixed-self version of bad faith. The second catches the open-self version. Most people are running at least one of them constantly, and the two feel completely different from the inside — one feels like resignation, the other feels like freedom — even though Sartre's point is that they're the same manoeuvre.
None of this requires a dramatic confrontation with the void. It requires noticing, this week, the one place you've been treating a choice as a fact.
Nothing Matters. Now What? picks up from there — what to do once the excuse is gone.