The Ladder of Inference

The ladder of inference is a metaphor for how mental models are formed. The ladder is a mental picture that describes the thinking process that occurs whenever we process new information. When we observe situations, we selectively notice some of the available sensory data, add our own meanings to the situation, make inferences or assumptions based on that meaning, and draw conclusions from the assumptions.

These assessments are usually made so quickly that we’re often unaware we’ve jumped up the ladder.

Now that we have reached conclusions we’re poised at the top of the ladder to take action. It’s the results of those actions influence what we notice in the future.

We have many deeply held, sometimes unexamined beliefs and assumptions about different aspects of our reality, and how well we fit in. These are our mental models. The creation of mental models is a necessary brain function. Our brain engages in a constant process of pattern making. This happens without our noticing that it happens. It’s how we instantaneously know a dog is a dog when we see one. It’s also why we gravitate toward what’s familiar, whether in the world of ideas, emotions, or the physical world.

Mental models are both helpful and limiting. They can help if we don’t have to analyze the appearance and behavior of a dog each time we see a new one in order to understand that it’s a dog. They can limit our thinking, our actions, our organizations, if the beliefs and assumptions upon which they are based are not examined and updated from time to time. Errors in judgment as we run up the ladder, and the ensuing action based on those errors, can run the gamut from trivial to catastrophic.

Here’s an example of how unexamined assumptions led to a tragic outcome.

You may recall the case of Amadou Diallo, an immigrant who was shot and killed in the South Bronx by four undercover police after doing nothing more than catching a breath of fresh air late one night outside his apartment building. As Diallo stood on his front stoop, four police officers approached to ask him some questions. This act, and Diallo’s responses, led to a rapid series of inferences based on false assumptions. The assumptions led officers to open fire. Over 40 shots later, they were stunned to discover that the gun they “saw” Diallo’s hand was nothing more than black wallet. How could that happen?

The observable data in this case is information that is “objective.” This is the kind of information that would be recorded on a video camera. What would a video camera have seen that night? A camera would have seen Diallo standing outside of a building at night, nothing more, nothing less. The camera could also have recorded the plainclothes officers’ car stopping in front of the building, and four men getting out – or it could have seen any number of other scenes and events.

However, people do not observe situations the way a video camera does. A video camera does not attach meaning to what it records. People do. Both Diallo and the officers ran up their own ladders of inference.

The first rung of the ladder involves selective data, the data that individuals observe. Think of the reports of witnesses to accidents, and how much they can vary according to what each individual may have noticed. Different individuals select or pay attention to different information. No one can possibly observe everything at once.

As Diallo stood on his stoop, he may have been daydreaming, taking in the night. He may not have noticed the car slowly turning onto his street, and may not have immediately noticed that the car had stopped, or that there were four men inside. The officers did not stop to notice whether Diallo had heard them speak, or if he understood them. They surely did not notice that his weapon was a wallet.

On the second rung, individuals add their own meaning to what they’ve observed. The meaning they add is consistent with their own beliefs about the world; these beliefs, in turn, are drawn from their own past personal and cultural experiences.

The officers attached the meaning of “suspicious” or “threatening” to their observation of Diallo. Diallo may have believed that the officers looked “aggressive” and “threatening.” Here is where the observable data undergoes extensive analysis and transformation. The officers have much experience patrolling dangerous areas, and began to make meaning of Diallo’s movements on the stoop based on that experience. Diallo, who may have had less experience in the Bronx at night, may not have immediately attached meaning to the car slowly moving down the street, but apparently did attach the meaning of “threatening” to the four men exiting the car.

We attach meanings to events automatically and without thinking. However, the meanings we attach to events may be very accurate – or may be completely inaccurate. Notice that the meaning that the officers and Diallo attached to their observations very much correlates with what the officers and Diallo EXPECT to see based on past experience.

Similarly, witnesses to accidents notice only certain elements of the accidents and even “make up” details that are consistent with what they expected to see, or fill in the details with plausible explanations.

The third rung involves making judgments, assumptions, and inferences based on the earlier experiences and the meaning that’s been added to the data.

One event or piece of data might lead to many different conclusions – as many conclusions as there are people observing or analyzing it.

In retrospect, it is clear that Diallo and the officers made some very different assumptions about the “observable data” – and that the assumptions both the officers and Diallo made were erroneous.

The officers made the assumption that Diallo was up to no good. As the officers proceeded to approach Diallo, they also assumed that Diallo was, at the very least, armed and dangerous, based on his retreat through the first door of the vestibule, and the fact that he was trying to pull something out of his pocket (and the meaning they attached to these actions).

Diallo, on the other hand, ultimately assumes that the officers’ intentions are not good.

When one of the officers asks Diallo to show his hands and other similar commands, he assumes Diallo understands English.

Later, after an officer fired the first shot, a second officer jumped off the stairs backwards in reaction, and a third officer assumed the second officer was shot – by Diallo.

Based on these assumptions, the officers concluded that Diallo was either engaged in the act of burglary, or was a criminal suspect in other crimes.

Further, the officers concluded that Diallo was trying to get out a gun to shoot them.

Diallo, for his part, concluded that the four plainclothes officers were thugs who were trying to rob him.

The officers developed a belief, based on their assumptions and conclusions, that Diallo was armed, dangerous, and in the act of drawing a gun. The first officer concluded that they were in imminent danger.

Diallo, in the meantime, panicked. He believed that if he could offer up his wallet, while retreating to relative safety inside his building, he could escape harm.

Therefore, Diallo continued to try to escape while also trying to extract his wallet.

Instead of clearing up the misunderstandings, this action precipitated a rapid series of actions based on a set of faulty assumptions and beliefs. Here’s what happened next. The first officer, hearing no response from Diallo to his verbal commands and seeing something black coming from Diallo’s pocket, opened fire.

The second officer, believing Diallo to be armed and dangerous, jumped backward in self-defense because he was convinced that Diallo, not the first officer, fired the shot.

The first and third officers, seeing the second officer jump backward, believed Diallo has shot him. The first officer retreated, still firing. The third officer reported later that he saw Diallo crouched against the wall where the second vestibule door was located, with a hand extended and something black in it. The third officer later reported that he was convinced he saw an entire gun in Diallo’s hand.

All four officers were stunned and distraught to ultimately discover that Diallo was unarmed and innocent.

In the case of Amadou Diallo’s murder, the results of the actions taken were so traumatic that the officers would be led to re-examine and question their previous beliefs and actions. The unavoidable question for them was how could they have been so wrong?

This is an example of actions based on unexamined assumptions that had extremely serious consequences.

But “going up the ladder” frequently happens in mundane, everyday circumstances as well.

Under more everyday circumstances, our assumptions and beliefs about groups of people, roles, or organizations that we interact with daily can easily remain unexamined. It can become easy to jump to conclusions when we’ve “been there, done that,” just as in the Diallo case.

Often, however, the results of the actions are not as unexpected or as extreme as they were in the Diallo example. Therefore, they do not cause us to examine our assumptions, beliefs, or our actions.

Let’s go up the ladder again. I’m a principal, and have had problems with parents. My mental model includes beliefs that the parents in my school’s attendance area are difficult, that they’d like to discredit me, that they think they know how to run a school, and that they would like more control. As a corollary to these beliefs, I feel a lack of respect and appreciation. These beliefs have been reinforced through past events and actions. Here is another example in this cycle of distrust.

At a large school event, I notice a parent deep in discussion with a group of other parents.

I selectively notice that the discussion is heated, with some parents raising their voices or moving closer to the others. However, I do not notice other parents happily engaged in various other activities at the event, or the many friendly greetings I receive.

Instead, I dwell on the series of conferences I’ve had lately with demanding parents who have high expectations. I add my own meaning to what I observe. When I see the small group of parents I find it threatening.

Now I quickly make an assumption – one which I may or may not be aware I’m making – that the issue being discussed is related to a decision I made last week concerning the parent’s child. I assume the group of parents is antagonistic toward me. Surely the parents are discussing a problem with the school.

Of course, they may actually be talking about their kids’ last ball game, or possibly working out a new idea to bring to the me and others at the school about a parent volunteer program --- or any number of other scenarios.

I conclude that the particular parent that I notice is at the center of the discussion is building support among other parents and will go to the school board to complain about me.

My conclusion leads to a belief that parents have little confidence in my leadership and, further, that even after all I’ve done, the community will never accept me anyway. I conclude I may need to defend myself at a board meeting. Why should I continue to go out of my way to involve them?

The experience has reinforced my belief that the parents are not “on my side.” The belief is about to influence my actions and will continue to flavor my interactions with parents.

As a consequence of my belief, I take the following action: I avoid the group and leave by another exit. I also make fewer efforts to reach out to parents over the next weeks and months. I may even complain to the board at some point about interfering parents.

As a result of my actions, the parents will notice that I’m keeping my distance and will, in turn, assume I discount their concerns and ideas. They will be less likely to approach me to discuss any ideas or concerns, and more likely to develop their own factions. They may, indeed, take their concerns to the board.

I’m stuck in a downward cycle, due to my unexamined assumptions. I will notice each time a parent seems to avoid me, generally neglect to notice any positive support from parents, and continue to erode my own support among parents. I will thus be confirmed in my original beliefs that parents are dissatisfied with me.

The reflexive loop leads downhill!

In the fifth discipline fieldbook, Schools That Learn, the authors say that “the ladder can be used in staff development, in the classroom, and in a variety of school and community meetings.” How can the ladder of inference metaphor be a useful in examining your own thinking?