For a single person, knowledge is usually binary: either you know something, or you don’t. If you know it, you can easily remember it, and then use it to make decisions. For example, if I know that Alice is a thief, I won’t invite her over to dinner. People can forget something, but they probably won’t if it’s really important, and what qualifies as “important” is pretty straightforward: your family, your house, your job, your health, your puppy. If I tell Bob that his house burned down, now that he knows that, I can easily predict his actions: call his family, drive there, take some time off work, file an insurance claim.

Knowledge in groups – companies, institutions, societies – is much more complex, because the ways people can share information (writing, speaking, body language) are really, really slow, compared to either thoughts or computers. For a group to “know” something the way a person does, there are five separate steps:

  1. First, someone within the group has to discover the knowledge; say, that Alice is a thief.
  2. Usually, this person won’t be the group’s leader; they can’t act by themselves. Therefore, they have to figure out who else in the group they should share it with.
  3. If the group is large enough, this might have to be repeated several times (up a chain of command, say).
  4. Once the information reaches, eg., event security, they have to decide what to do based on what they learned.
  5. Finally, they have to implement the plan, and not let Alice into the building.

To add extra complexity, it’s a lot harder to know which facts are important, and which aren’t. If a Wal-Mart greeter finds that Wal-Mart’s TV supplier has gone bankrupt, they might not care very much; they have the same job either way. Conversely, if the CEO of Wal-Mart desperately wants to know something, the greeter probably never hears about that. Maybe the CEO would even give the greeter a big bonus if they found out, but it doesn’t matter, because there’s no straightforward way to tell them.

Hence, “ghost knowledge” is one possible term for something a group “knows” – in the sense that someone in it knows – but where it might as well not, because the group can’t meaningfully act on that knowledge. One famous example is the Nigerian “underwear bomber”, who smuggled explosives onto a US-bound flight on Christmas 2009, but then failed to detonate them. ( His own father had, a month before, traveled to the US embassy and told the CIA about his son’s extremism, but this information never made it to airport security. For a contemporary intelligence agency, simple math demands that almost all knowledge is “ghost knowledge” – a computer can tap undersea cables and read off terabytes every second, but the ability to orient, decide, and act is still limited to the speed of a small number of human managers.