Greg Gigerenzer, the man whose work inspired Gladwell’s Blink, believes that our Unconscious minds are more rational than most of us credit it. He argues, (convincingly), that we should use our unconscious mind to make certain kinds of choices. If a situation is complex, and if the data is ambiguous, go with your gut.

Pragmatic Application

Fast and Frugal Tree

Book Notes 

Chapter 1 – Gut Feelings

This book claims to be about asking; Where does our intuition come from?

We are not perfectly rational beings. This seems obvious but many a writer and scientist give advice they can’t follow, (statistical analysis of pros and cons, etc).

Gives the example of the recognition heuristic. We trust things we recognize. Your Unconscious mind is full of these heuristics, all that seem to have been beneficial in our evolutionary development.

The opening chapter gives an example of the Gaze Heuristic, this is an example that was used in a seemingly random essay I read about before reading this book. It is about how the brain is not a computer. The essay was by Epstein and is very important to the creation of my book. I see this is a beautiful case of synchronicity,

The stories he shares in the introduction is to show that Intuition is real and we all use it.

He defines Intuition or Get Feeling as

That which appears quickly in consciousness whose underlying reasons we are not fully aware of, and is strong enough to act upon.

The real question is, When can we trust our intuition. To understand this, we need to understand how Intuition works, and guess what? lol, thats what this book is going to do.

He believes our intuition is our rationale.

He believes it works this way;
-simple rules of thumb,
-which take advantage of
-evolved capabilities of the brain

Rule of thumb and heuristic are the same thing in this book.

Nature gives humans a capability, and extended practice turns it into a capacity.

Two models we can assume about Gut Feelings
-We are machine like and our unconscious is solving complex problems with complex computations
-We are evolved organisms that rely on simple rules of thumb that take advantage of our biology.

First goal of this book is to explicate the hidden rules of thumb that underlay intuition
Second, to understand when intuition is likely to succeed and when it fails.

He believes that logic is a system of thought that has dominated us for too long, and that the mind is more of an adaptive toolbox (Pragmatic view).

Chapter 2 – Less is (sometimes) More

(These people show their points through stories) Opens with story of sick kid dying because doctors wanted to find what was wrong, rather then just give the kid a caring environment.

The human capacity to lose memory is molded by the changing nature of our environment. (pragmatic)

He asks the ecological question – what kind of environment would…
In this case, what kind of environment would perfect memory be useful? a Static world.

When babies are learning language, forgetting is essential. Start small. Speak to them in simple short sentences, and they will master that and move on to higher sentences. This strategy can be applied to learning anything. (80/20) principle lol.

“Create scarcity and develop systematically”

Less choice increases sales.

Telling novices to slow down during a skill is good, bad when they are experts.
Experts do better when they are distracted. Worse when they are asked to think about what they are doing.
He offers the the technique I use to mess people up. Ask them how they do some sport move.
You force them to think about it and they are an expert it can impair them.

Two assumptions of our time that are wrong are
-More information is always better
-More choices are always better

He states that less is truly more when
-There is a beneficial degree of ignorance
-Unconscious Motor skills
-Cognitive Limitations
-The freedom of choice paradox
-The benefits of simplicity
-Information Cost

Chapter 3 – How Intuition Works

He believes that human cognition is a “toolbox of instincts” that manifest as rules of thumbs that help humans deal with the primary challenge of human intelligence: to go beyond the information given.

With the optical blind spot as example, he is arguing that our brains do and must make guesses about reality. We do not perceive reality as it is.

He argues that intuition works the same as these perceptual “bets.”

Rules of Thumb
-Light comes from above (sun was only like source of millions of years)
-There is only one light source (sun again)
-If a person looks at one thing longer than the other, he likely desires that thing (shaky, context important)

He argues that gut feelings arise from rules of thumb, and that rules of thumb arise from both our evolutionary brain and the environment.
-We have a gut feeling
-The feeling arises from a rule of thumb
-A rule of thumb is used when our evolutionary capacity fits the environmental structure.

The two ways to understand behavior

This book argues for the adaptive model, that the mind and the environment are married, and must learn to get along with each other.

The tendency to explain behavior without taking into account the enviroment is whats known as “The Fundamental attribution error.”

Tic-for-tack is a rule of thumb most people use. “Be kind first, keep a memory of size one, and imitate your partner’s last behavior.” (This is a social strategy)

The takeaway from this chapter is
-Gut feelings arise from rules of thumb
-Rules of thumb arise from the interplay between our environment and our evolved capabilities.

Chapter 4 – Evolved Brains

“In order to understand human behavior, we need to understand that there is an evolved human brain that allows us to solve problems in our own way – different from the reptiles or computer chips.”

Culture arises from humans unique ability to accurately and effortlessly imitate.
-This could be a great example of why one should find a mentor.

In order to make a computer with human like intelligence, we’d have to understand our rules of thumbs.

This author thinks that day is far off, if ever accessible.

He likes to think of the mind as a tool box with three layers
-evolved capacities
-building blocks that make use of capacities
-rules of thumbs composed of building blocks

Rules of thumbs are like molecules
Building blocks are like elements
Capacities are like particles

Men and women are equally intuitive, culture molds how we are different.

Chapter 5 – Adapted Minds (OUR ENVIRONMENT IS CRITICAL)

To understand behavior, one has to look at both the mind and the environment.

“A man, viewed as behaving systems, is quite simple. The apparent complexity of his behavior over time is largely a reflection of the complexity of the environment in which he finds himself.”


He finds people interact 50% less if they live on different floors so he keeps all his workers on the same floor.
Hired everyone at the same time to create equal footing
Daily Social Gatherings
When someone publishes a paper, THEY buy the rest cake lol.
Has an Open Door Policy

This Environmental piece of the behavioral puzzle is the big set back in scientific studies; an unnatural environment.

Rule of Thumb
Take The Best – We base our intuition on one good reason.

Rules of Thumb are better when an optimal choice is not knowable.

Essentially, good algorithms are clever, conscious rules of thumb.

Chapter 6 – Why Good Intuitions Shouldn’t be Logical

He critiques, “Thinking Fast, and Slow.” Many people assume mathematical logic = rational.
He his voicing an opinion Jung and I share. I agree. The static, predictable world of formal logic is not how the universe works. We operate in fundamental uncertainty.

He calls the Linda test “content-blind”

Opinion – A lot of science studies seem to be about how cleverly can I trick people, capture this trickery in a measurable way, and publish my results. This is not the case in all ways, but seems to be common. There is much more that goes into the creation of experiments. Researchers exploit Rules of Thumbs in their experiments. This is where the real goodies are.

Our Rules of Thumb are more adaptive than Logic.

Finding and cataloguing Rules of Thumb and Heuristics would be a fun, life long collection.

The dawning realization of this book is that logic is a tool we have created, but there is a tool that is better in some cases, and it is our Evolutionary Heuristics/Rules of Thumb.

Part 2 – Gut Feelings in Action

Chapter 7 – Ever Heard of…

Recognition memory is better then recall memory at the start and end of life.
(This is an evolved capacity which building blocks and rules of thumb arise from.)
The recognition heuristic is not to recognize objects, but to make inferences about something else.

The Recognition Heuristic

An inference is when there is a dichotomy of choice
A personal choice is when there are multiple options.

The recognition Heuristic, when applied to an inference is
If you recognize one object but not the other, then infer that the recognized object has a higher value.

Essentially, he is giving multiple examples of how knowing less, and guessing based on recognition is a better then chance guess and sometimes outperforms experts.

He calls the “Intelligence of the Unconscious” the evaluating of whether or not a Rule of Thumb is worth acting upon.

AN effective use of this heuristic depends on

Chapter 8 – One Good Reason is Enough

He contends that many people base their judgments on “one-reason decision making”
And that this is good.

This chapter will focus on Recall Memory

These seems to be a connection between instincts, archetypes, heuristics, and Rules of Thumb. I need to do some work to tease these apart and understand how they differ.

Coevolution is the simultaneous evolution of genes (coding decision rules) and the environment.

The string Heuristic of Political parties is an interesting one (pg 143)

Sequential Decision Making
When one considers another que because the first one did not allow for a decision.

Take The Best heuristic 3 building blocks
-Search Rule: Look up reasons in order of importance
-Stopping Rule: Stop search as soon as the alternative for one reason differ
-Decision rule: Choose the alternative that this reason suggests

The overall lesson is to trust your intuition when thinking about things that are difficult to predict and when there is little information.

Argues that evolution and intuition work on the One Good Reason Heuristic
Recommends we design our world this way (Simple, clear choices)

This looks like
Create a ranked value system
If first rule shows a clear winner, go with that option, if not, filter through 2nd value
And filter through new rule when needed.

Chapter 9 – Less is More in Health Care

Rule of Thumb
Trust people in white coats
Don’t ask doctors what they recommend, ask what’d they do if it was their mother

Shares story of doctors over-assigning IC rooms, given a calculating device to fix this over-assigning, and once the new tool was used for a while and removed, the doctors had developed an unconscious rule of thumb where they didn’t need the calculator anymore. (170)

When there is high uncertainty, simple diagnostic tools perform better.

Fast and Frugal Tree is like the Flow Chart (This is a tool)
Asks a few yes or no questions.
Each answer allows for s decision to be made.
(Essentially a flow chart of the 80/20 principles.

Most important factor is first.
I am attempting to create good Fast-and-Frugal trees for people looking to change a habit. (and heal)

Fast and Frugal Tree consists of three building blocks
Search Rule” Look up factors in order of importance
Stopping Rule: Stop the search if a factor allows it
Decision Rules: Classify the object according to this factor

Fast and Frugal Trees are the 80/20 of Full Trees

Less can be more and nothing is absolutely certain. (lol, language comedy here)

Master the art of focusing on what’s important and ignore the rest.

Chapter 10 – Moral Behavior

Social rule of thumb
Don’t break rank
Do what the majority of your Peer’s do

The opt-out phenomenon is super powerful
99.9 french are organ donors (opt-out model)
28 percent of Americans are donors (opt-in model)

We tend to follow the Rule of thumb calls
Default Rule (Seems to be something that’ll show up in Nudge)

He thinks that morality is like grammar, we are born with an innate ability to learn morality and it varies from subgroup to subgroup like dialects.

Three Principles of Moral intuitions
Lack of awareness – is quick and unconscious like gut feelings.
Roots and Rules – the intuition is attached to one of three roots (individ, family, or community) and to an emotional goal or desire.
Social Environment – Moral behavior is contingent on the social environment. Some moral disasters can be prevented if one knows the rules guiding people’s behavior and the environments triggering these rules.

We are a culture rooted in the individual. I am attempting to connect the individual with the family and the community. My perspective is, we start healing the whole by healing ourselves, then we can help our families heal themselves, then our communities.

A satisfier is someone who focuses on the few important.A maximizer is someone who tries to look at all possible options and pick the best.

His book is about simple rules vs complex reasoning

Chapter 11 – Social Instincts

He believes most social interactions are not predicated on complex unconscious calculations, but rather on Social Rules of Thumb, which he calls social instincts.

He argues that we have two primary social instincts
Family Instinct
Tribal (community) instinct

Kin selection – when an individual does something anti-selfish to help out kin.

Our Tribal instinct separates us from all other animals. We are able to identify with a symbolic group, like a religion, or nation, etc.

Our Instinct to imitate is the foundation for culture.