System I & System II

Here’s a puzzle: Linda is 31 years old, single, outspoken, and bright. She majored in philosophy at an American university. As a student, she was deeply concerned with discrimination and social justice issues. Which is most probable?

1. Linda is a bank teller.

2. Linda is a bank teller and active in the feminist movement.

3. Linda is a Supreme Court Justice.

4. Linda is an eye doctor aiding underserved communities in Ghana.

Daniel Kahneman, a Nobel Prize-winning economist, presented a question like this in Thinking, Fast & Slow. Before I reveal the answer to the above question, let’s explore Kahneman’s seminal idea of System I and System II thinking.

System I is fast thinking. Because this is Turtle’s Pace, let’s imagine a rabbit. System I is automatic, unconscious, and uses heuristics to make quick decisions. We use System I for solving basic problems like 4-1, brushing our teeth, driving a car on an empty road, reading text on a billboard, or understanding simple sentences. System I conserves mental energy, so you can bounce along like a rabbit.

System II is slow thinking. Picture a turtle—arduously crawling through the dirt. System II requires effort, conscious thought, and rationality. We use System II for complex scenarios: parking in a tight space, solving 38x24, determining appropriate behavior in a social setting, or solving a peculiar logic puzzle. System II helps us arrive at more nuanced, accurate decisions, but it consumes a lot of energy.

So, who is Linda?

If you used System I, you likely selected 2. Linda is a bank teller and active in the feminist movement. That’s because your brain made cognitive shortcuts about Linda’s story—if she was outspoken and passionate about social justice in college, she must be active in feminism today. Humans love stories, so it’s natural for narratives to guide our thinking. But they aren’t always accurate.

If we use System II, we can better understand the scenario. First, the question asks, “which is most probable?” Thinking in terms of probability can narrow our options.

• Most people know there are only nine Supreme Court Justices, so it’s highly improbable for answer 3 to be correct.

• Most people could rationalize that there are far more bank tellers than eye doctors in the U.S. (364K tellers and 39K optometrists in 2021, according to the Bureau of Labor Statistics). Coupled with the specifics (eye doctors working in Ghana), it’s clear that answer 4 is also improbable.

• Where System II shines is differentiating between answers 1 and 2. Let’s consider a Venn Diagram:

We can see that answer 1 (bank teller) contains answer 2 (feminist bank teller) and is always more probable. “Linda is a bank teller” does not prohibit Linda from being a bank teller and a feminist. Therefore, the most probable answer is:

1. Linda is a bank teller.

We spend much of our time in System I to conserve energy, and that’s good. But for the handful of scenarios each day that require deep, careful thought—slow down and deploy the turtle (System II).

One-Way & Two-Way Doors

Amazon popularized the idea of one-way and two-way doors to encourage employee decision-making and appropriate risk-taking.

One-Way Doors aren’t easily reversible decisions—like choosing hardware for tech projects, settling on a building location, and getting married. One-Way Doors require careful thought and planning, and they’re the perfect use case for System II, turtle-like thinking. But the cost of One-Way Doors is high—as the decision is large, slow, and risky.

Two-Way Doors are reversible decisions, such as software changes, attending an event, or picking a movie to watch. You can walk through the door, see if you like it, and walk back through it if you don’t. Most decisions are two-way doors. You can move fast, unburdened by the need for approval or analysis paralysis.

When faced with a One-Way Door, see if you can transform it into a Two-Way Door. For instance, say you want to move across the country. Before buying a new home or starting a new lease, vacation there for a week. Stay in a hotel, rent a car, and imagine what it’s like to be a local—go to the grocery store, walk around the park, visit the library, etc.

Don’t view decisions as “one-size fits all.” Ask yourself: What’s the worst that could happen? If the risk is low and the choice is reversible, step through that Two-Way Door.

Red Pill or Blue Pill

Near the beginning of The Matrix, the protagonist receives two pills. Either he can take the Blue Pill to expunge dangerous thoughts and retain his everyday life or take the Red Pill and learn an unsettling but life-changing truth. Many controversial ideas have stolen this Red Pill/Blue Pill concept, and I will shamelessly do the same!

Consider Plato’s Allegory of the Cave—in which prisoners are chained inside a cave and see shadows on the wall. They don’t know where the shadows originate or that these shadows are a blurred image of a richer reality. These poor souls don’t know they exist in a cave because the cave is all they know—they have no concept of life outside. Plato intended for this cave to represent most of humanity. The job of philosophers, ergo, is to escape the cave and see the world for what it is.

Seeking truth (escaping the cave) is the Red Pill. Accepting ignorance (finding comfort in one’s shackles) is the Blue Pill. There are many of these decision points in our lives; for instance, you may have the opportunity to push yourself physically or mentally to complete a project. If you don’t try, you can’t fail, and you won’t have to deal with the possibility of failure, so you can continue finding solace in fantasies about your potential. The same is true for moving to a new place, changing careers, starting a relationship, going to therapy, or having a difficult conversation. The Blue Pill maintains the status quo, despite the potential regret for the chance not taken—which slightly lowers your quality of life moving forward. The Red Pill could have great or terrible outcomes, but which one you get is unknown.

The Red Pill is scary, tastes nasty, burns your throat, and gives you piercing headaches. The Blue Pill is like your favorite potato chip—tasty, familiar, and comforting. We unconsciously gravitate toward the Blue Pull: Rather than challenge our beliefs, we imbibe information that comforts us. Because once you see something new, you can’t unsee it—it’s a one-ticket to an unknown world.

Junk Drawer

1. A simple tool to clean up pictures

2. This atlas of uncontacted peoples

3. This use of variable font-weight to skim-read more effectively: bionic reading