Chapter 19 — Black Swans

For roughly fifteen hundred years, "black swan" was a Roman figure of speech for something that could not exist. The poet Juvenal, in the second century, described a impossibly perfect woman as rara avis in terris nigroque simillima cygno — a bird as rare on earth as a black swan. Everyone knew swans were white. The phrase survived for over a millennium precisely because it named an impossibility, the way we might say "when pigs fly."

Then, in January 1697, a Dutch sea captain named Willem de Vlamingh sailed up a river on the western coast of a barely-charted continent and saw, gliding across the water, swans that were black. He named the place Swan River; the certainty of fifteen centuries was undone by a single afternoon's observation. The lesson the philosopher Nassim Taleb later drew from this — and built two books around — is the one that matters for negotiation: no amount of confirming evidence (every white swan you've ever seen) can prove a universal truth, but a single contrary fact can shatter it. Taleb used "black swan" for the rare, unforeseeable, enormously consequential events that blindside us and that we pretend, afterward, we should have seen coming. Christopher Voss borrowed the term for something more everyday but just as decisive: the pieces of hidden information sitting inside almost every negotiation that, once uncovered, change everything.

A note on honesty before we go further: Taleb's black swans are, by his strict definition, genuinely unpredictable. Voss's negotiation "black swans" are usually not — they're things the other side knows and you don't, which means they can often be dug up if you go looking. This chapter uses the looser, more useful negotiation sense, while tipping its hat to the stricter one.

The three kinds of knowledge

The most useful way to think about hidden information comes from an old framework about what we know and don't:

Figure 19.1. Most negotiators prepare the top row — they marshal their facts and list their open questions. Deals are won and lost in the bottom box: the information you don't know you're missing. The whole art is converting unknown unknowns into known ones.

You walk into a negotiation with your known knowns — the facts in hand — and, if you've prepared, a list of known unknowns, the questions you mean to ask. But the decisive information usually lives in the third box: the unknown unknowns, the things you don't even know to wonder about. The counterpart has a deadline you've never imagined. There's a second decision-maker you've never met. They have a non-obvious reason to want this deal specifically — a strategic fit, a personal stake, a fear — that, if you knew it, would rewrite your sense of the whole leverage map. A single such discovery can flip a negotiation from losing to winning.

How to hunt them

You cannot list what you don't know to look for, so hunting black swans is less about questions and more about posture. Three habits do most of the work.

The first is relentless, genuine curiosity, channeled through the listening skills of Part IV — because black swans don't show up in formal position statements; they leak. They surface in an offhand remark, a flash of emotion, a hesitation, the thing said while packing up to leave. This is why getting face-to-face, or at least voice-to-voice, matters so much: the unguarded moments where hidden information slips out don't happen over email. The negotiator who listens for the throwaway line catches what the negotiator running through an agenda misses.

The second is the discipline of treating apparent irrationality as a clue. When the other side does something that seems crazy — refuses an obviously good deal, fixates on a term that shouldn't matter, behaves with inexplicable urgency or inexplicable stubbornness — the lazy conclusion is "they're irrational." The professional conclusion is "there is information I'm missing that would make this behavior make sense." People are almost never as crazy as they look; they're operating on constraints and values you can't see. They're not crazy — you're missing a black swan. That reframe turns frustration into investigation.

The third is to notice what is conspicuously not said — the topic they steer around, the question they answer narrowly, the silence where you expected detail. Absence is information.

The honest frame

Not every negotiation hides a game-changer, and you should resist the romance of the secret revelation. Forcing a conspiracy theory onto a straightforward deal will make you paranoid and slow, and sometimes the other side really is just doing what they appear to be doing. Nor can you guarantee you'll find the black swan that's there; some stay hidden, and you lose for reasons you only understand later, if ever. What the black-swan posture buys you is not certainty but the right stance — curious, humble, alert to the possibility that the most important fact in the room is one you haven't learned yet. That stance is correct even when there's nothing to find, because it's the same stance that makes you a good listener and a hard person to fool.

One of the most common hidden forces, and one worth its own chapter, is something every counterpart carries into the room and few will state outright: their sense of what is fair.

Try this. Before your next negotiation, write the sentence: "If the other side does something that looks irrational, my first move is to ask what I don't know — not to conclude they're being difficult." Then, when it happens, get curious out loud: "Help me understand what's driving the urgency here." You're fishing for a black swan.

Sources & notes

The black-swan metaphor's history — Juvenal's rara avis line, the European assumption that all swans are white, and its overturning by the discovery of black swans in Western Australia (Willem de Vlamingh named the Swan River in January 1697; earlier sightings date to Antonie Caen in 1636) — is well documented (Wikipedia, "Black swan theory"; Australian Dictionary of Biography). Nassim Taleb developed the modern concept in Fooled by Randomness (2001) and The Black Swan (2007). The "known knowns / known unknowns / unknown unknowns" framing was popularized by Donald Rumsfeld (2002) and has older roots in the Johari window. "Black swans" as hidden negotiation information, and "they're not crazy — you're missing information," are Voss's adaptations (Never Split the Difference, 2016); this chapter notes the gap between Taleb's strict (unpredictable) and Voss's looser (discoverable) usage.