This is the last page of the handbook. Start at page one.
A year ago, I was fundraising for a startup. In the process, I met a lot of investors. It struck me how uniformly insightful they were. I had not seen anything like it before.
Their wisdom extended beyond domain expertise. They seemed to have a high-level ability to connect dots between disparate concepts with a degree of pragmatism that made me wonder, "Are these people exceptionally bright?"
I didn't have an answer. All I knew was that they didn't seem to be innately smarter.
A couple months later, an investor friend asked me, "Have you heard of mental models?" I hadn't. I looked them up, and everything suddenly clicked: Investors didn't necessarily have greater intelligence — they aren't necessarily capable of being rocket scientists — rather they learned tools for making good decisions.
I didn't even known there was a toolbox to begin with.
I began researching critical thinking. I was dismayed to only find material from university lectures. Expectedly, it was dry and uninspired. Unexpectedly, it was also sparse and disjointed: There wasn't a unified framework to deploy the key 20% of critical thinking concepts into daily conversation and writing.
And none of the examples were illuminatory. Or engaging to read.
So I decided to put the work into writing what I believe is the first holistic, layperson's guide to critical thinking.
Hopefully the way I'm presenting fallacies, biases, and models makes their relationships seem self-evident, but these topics aren't historically taught within a singular framework. Nor are they accompanied by prescriptions for refutation.
I had to rigorously think through how everything in this guide connected. And I had to generate original refutations, techniques, and models.
By the way, if you've read this far, you'd be silly to not say hello on Twitter 😜 I'll be posting there when my next handbook is out.
Don't just walk away
You're almost done! But we need to make sure this was worth your time.
Consider how we read dozens of books and articles every year. And how we participate in thousands of conversations.
Yet, how much of it do we remember? How often do we learn something that makes us think "Wow, that completely changed my perspective!" then revert to our old habits the very next day?
Reflect on all the TED talks you've watched. Your fading memories of those are a graveyard of unapplied insights.
Similarly, the 20 minutes you spent reading this handbook was a waste of your time if you don't spend another 20 memorizing the cheat sheet at the bottom of this page.
In this guide, we've demystified arguing, deciding, and persuading.
We know that "conversational intelligence" is simply a learnable skill. To be a successful writer, speaker, or businessperson, critical thinking plays a huge part — because forming persuasive arguments is at the heart of every form of communication.
You don't need to be a math genius with a high IQ to be world-class at these skills.
So it's worth repeating: Many of the people you admire aren't necessarily unattainably smarter than you. They're likely just highly consistent in their pursuit of good conclusions. They don't let their "gut instincts" blind them.
To be like them, you'll need to start by remembering the material in this guide. The cheat sheet alone won't be enough. You'll also need to put this into practice.
So this brings us to our final topic: debate your friends.
"I have no special talent. Curiosity, obsession, and dogged endurance combined with self-criticism have brought me to my ideas."
Debate your friends
Using the upcoming cheat sheet as a reference, debate your friends over the phone or in-person.
Find out who's interested in debating you by posting something like this to Facebook:
Who wants to debate me so we can get good discussions going? Possible topics: death penalty, pardoning Edward Snowden, designer babies, the ethics of eating meat, the ethics of keeping animals in zoos, legalizing drugs, or any other topic you care about. Just leave a comment saying whether you're for or against the topic you want to debate me on, and if I'm the opposite, we'll chat!
If you make a habit of having these conversations, you'll gradually become wise on all the topics you care about. You'll have heard the prominent perspectives. You'll be that person who knows their shit.
(Throw in mental model practice at work for good measure, and you'll be on your way to becoming a noticeably brighter person.)
But, to have productive debates with your friends, you'll first need to learn how to actually have a debate! Let's dive in.
How to debate
The argument framework
As a reminder, when someone presents an argument, consider using this framework to the extent you're interested in ensuring their reasoning is sound. In short, you want to sanity check their evidence, premises, and conclusion:
- Ask them to clearly state their conclusion.
- Ask what premises ("reasons") lead to their conclusion.
- Ask what evidence they have to support their reasons.
- Check their conclusion against the ten fallacies. Refute any fallacies that exist.
- If the argument still seems fishy, check their evidence against the three biases. Point out any that exist. Explain that any premises built on these biases must be re-examined.
"The body protects the brain. Skepticism protects the mind."
Good debates share the goal of getting at least one party closer to the truth. That includes you too. Don't just look for opportunities to reaffirm your position.
You must be ready to disavow your conclusion the moment you're proven wrong. Keep your ego small. Never double-down and cling to your emotional attachment.
Consider how the only debates Elon wants to have with you are about his mistakes:
I've hardcoded beginning and end times. Just hit play and let it run until it pauses.
The second goal all good debates share is developing a mutual understanding of why each party thinks the way they do. This is how you'll improve your arguing technique.
To help accomplish these two goals, let's conclude by learning The Rules of Debating.
"The truth will set you free, but first it will piss you off."
When debating another student of critical thinking, consider these rules:
- Opponents will pause and think before responding to avoid knee-jerk reactions.
- Opponents will not introduce new arguments until prior ones have been addressed.
- Opponents will cede their biases and fallacies whenever they're accurately identified.
- Opponents will not repeat themselves if they were understood the first time.
- Opponents will speak slowly and will not speak over one another.
You don't have to state these upfront, but whenever one is violated, kindly point it out.
(As always, these rules are included in the cheat sheet for easy referencing.)
One of the above rules is worth discussing further: Speaking slowly.
Many people argue quickly. Either because their adrenaline is pumping or they think the quicker they speak, the more authoritative they'll sound.
Or, worse, sometimes they'll talk fast because it lets them slip in dubious conclusions among their sound ones. They know that their speed makes it hard for opponents to critically assess everything they're saying.
This is a conman's tactic.
So point out whenever someone is talking too quickly. Kindly ask them to slow down: If they have confidence in their arguments, they will let each one be carefully assessed.
Here's an example of a reasonable debate. See if you can spot any rules being broken:
(No, I am not the Ben Shapiro in that video. I am Julian Shapiro.)
🤔 If you want more friends who can debate toe-to-toe with you, share this guide with them: julian.com/argue. If you record a great conversation and you obtain consent from both parties to publish it, tweet me a link to it so I can feature it!
Want to learn more?
This guide does not purport to teach you the entirety of critical thinking. The parts it does teach (fallacies, biases, and models) are themselves not taught in their entirety.
Instead, I gave you the 80/20 — what you need to know to get going.
If you'd like to continue your learning, check out these really good books:
- Book: Understand peoples' biases so you can dissect their irrational behavior.
- Book: A reference with answers to your remaining technical debate questions.
- Book: If you want to teach your kids critical thinking, read this first to understand how.
- Book: How to be skeptical of ideas, people, and data. A good gift for the superstitious.
This handbook was not inspired by these books, so they're mostly all-new material!
🤔 If you like how I wrote this guide, you might like the Build Muscle handbook too.
If you'd like to thank me for this handbook 😍
The best thanks I get is when you share this with friends and coworkers. I spent hundreds of hours writing this. And I'm giving it away for free.
If you like the insights I've shared and the resources I've put together, please share the handbook with a friend who could benefit from it.
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If you liked the quality of this guide and want to learn how to play piano, how to write fiction, or how to speak Chinese, get excited because I'm releasing those guides next.
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- The more we think critically, the more energy we must expend and the less egotistical we have to be about the quality of our gut instincts. The more self-aware you are about how you're thinking, the more often you'll detect when you could be using a model. And the less often you'll rely on biases and fallacies.
- To develop this awareness, you must recognize when you're researching or arguing. Arguing: Am I deciding between which option to choose, or how to prioritize options? Researching: Am I searching for key information, root causes, or inner-workings?
- Whenever you start furrowing your brow to figure out something that's unusually hard, you may have begun arguing or researching something important. If so, pause to deflect all snap judgments. In this zen state of awareness, run the arguments in your head against the list of fallacies and biases. And see if you can use any of the 5 mental models to better examine the evidence.
- Biases cause people to overlook opposing evidence. When this happens, opponents will often resort to fallacies to try to win the arguments.
- Emotional attachment bias• Description: A stubborn, irrational adherence to a view.
• First, find a principle your opponent values, e.g. "Do you care about social equality or national security?" This gives them something concrete to pivot their position on.
• Next, weaken their mental barriers by stating, "I'm not going to try to change your mind. Here's just another way to look at it that I think you'll appreciate it."
• Then frame your argument around their favored value: Spend time thinking about all the ways you can justify your conclusion by tying it back to their values.
- Familiarity bias• Description: A strong preference for what you’re familiar with.
• You can identify this bias in yourself and others by seeing if you/they can form a convincing argument for the view that opposes theirs.
• If you suspect your opponent is relying on familiarity bias and they won’t consider the opposing view, present them with counter-evidence and ask them to explain step-by-step why your new evidence should be discarded in favor of theirs.
- Stereotype and anecdote bias• Description: Relying on stereotypes and anecdotes instead of well-researched facts and the scientific consensus.
• These are simply refuted by requesting evidence. Opponents must answer, "What should I type into Google to find evidence supporting your claim?"
- Don't argue with people who don't actually want to debate. Tell them: "If you want to have a constructive conversation, you'll need to fully form a counter-argument for my central argument. Again, my argument is..."
- If they're debating you but they’re using fallacies, pause them each time they use one: Point out that a fallacy is "a trick to hide a lack of evidence or divert attention" then explain which fallacy they're using and how it works to deceive.
- Don't outright dismiss arguments: If a fallacy didn't corrupt a central argument or misconstrue your argument, their conclusion may still be sound.
- Red herring• Description: Introducing a point that has little relevance to the argument.
• Refutation: "Walk me through every step connecting the significance of your new point to our actual topic. If you can't prove the connection, you're diverting attention because you lack evidence to win."
- Quibbling• Criticizing an argument based on how it's delivered, e.g. tone of voice or language.
• "How I express my argument has nothing to do with the strength of the argument. So you're purposefully diverting attention and criticizing me because you can't win by criticizing the real argument we're having. Prove me wrong by presenting all your evidence right now. Go ahead and convince everyone."
- Ad hominem• Criticizing your opponent despite their character having no relevance to the argument.
• "How does your criticism of me have any bearing on the strength of my evidence? If you can't step-by-step draw the connection between the two, you're resorting to bullying because you know you can't win against my real argument."
- Middle ground• Claiming the middle ground between opposing views is inherently a good conclusion.
• "This is why your logic doesn't work: If you were pro-slavery and I was anti-slavery, your logic would have us compromise by doing something like only enslaving men. In other words, your conclusion is disproportionately bad, so the middle ground is still bad. We're going to continue this debate until a conclusion supported by logic and sound evidence — not arbitrary compromise — is found."
- False dilemma• Stating there are only two reasonable conclusions when in fact more exist.
• "You want us to believe there are only two reasonable paths to consider. But, how about [alternative #1]? Or [alternative #2]? If I can easily keep generating reasonable alternatives to your two paths, you can't keep trying to deceive people into thinking there are only two. You'll need to re-examine the evidence and choose the most logical path, not simply the one you're hoping we choose."
- Slippery slope• Claiming an opponent's conclusion will lead to a negative chain reaction, and that the conclusion must therefore be disqualified so we can avoid unforeseen risk.
• Read the full refutation here. In short: "We can't be afraid to take a sound first step today because of the unprovable chain of consequences that might result in the future. If you don't disagree that this first step is sound when isolated from future consequences, then it's the right step to take now. Otherwise, we're living in fear and will never improve our way of life."
- Correlation vs. causation• Mistaking a shared trend between two things as a relationship between them.
• "Walk me through every step taking you from what you claim is the cause to what you claim is the result. If you research fully, you'll realize there is no proof of a full connection. So when you try to walk me through it, the moment you reach that link in the chain that's bogus, you have to throw out all subsequent links and start over."
- Bandwagon• Citing popular opinion as evidence.
• "You know that for centuries people thought the world was flat and that slavery was justified, right? The masses' opinion has never reliably reflected the truth. Even when the truth is found (like it has with the lack of a link between autism and vaccines), it still takes decades for people to accept it. So 'what everyone is saying' is not sound evidence for your argument. Find proof."
- Incredulity• Dismissing evidence on the grounds that you're skeptical of it.
• "Your argument boils down to, 'Because I have a hard time believing it, it should automatically be assumed false.' That makes no sense: You're stating your personal ability to understand something supersedes expert research. But many people have a hard time believing many things: If you explained quantum mechanics to a child, do you think they'd wrap their head around it? No, and their inability to do so has zero relevance to whether it's true."
- Burden of proof• Implying your conclusion must be considered true unless your opponent can find evidence to disprove it.
• "A reminder how debates work: Each side argues their position with undeniable proof. Instead, what you're doing is claiming that whatever you're arguing for is somehow true by default unless I can prove you wrong. That's an illogical argument structure that can be used to successfully argue anything your mind can make up. For example, 'Unless you show me evidence disproving the prediction that the world ends in 2020, we should assume there's truth it.' Why? Because an ancient tribe said so?"
- Genetic• Claiming the validity of evidence can be judged purely by its source.
• This is very hard to refute. Try sharing the section on scientific consensus with them.
Critical thinkers create their own models as needed: Watch for the complex tasks you routinely encounter. Identify commonalities among their solutions so you can work backwards to develop frameworks to convert data into similar solutions.
- Prioritize tasks• Do not blindly process tasks in a first-in/first-out order. If a task is important and urgent, do it now. If it's urgent but unimportant, delegate it. If it's important but not urgent, schedule it for later. If it's unimportant and not urgent, cancel it.
• To measure the urgency and importance of a task, consider the impact it'll have in 10 hours from now, 10 weeks from now, and 10 months from now: The more it must be done soon in order to be done or done well, the more urgent it is. The more impact it'll have on the long-term, the more important it is.
- Decide between options• Confront and measure the values underlying your decision making so you can overcome the short-term minutiae clouding your judgment. There's a set of core values every project or business decision relies on.
• Starting a project (career, hobby, or business): Knowledge, money, exercising your talent, fame, power, adventure/fun, low risk of failure, low stress, and human connection.• Business decision: Financial stability, team happiness, financial growth, brand impact, knowledge, time stress, resources stress, and customer experience.
• Depending on which category you're facing, list the corresponding values one per line. Then write the two projects/decisions you're considering beside the values. Next, draw arrows from the values toward the two choices. Make the arrows one to three units in length depending on how much the decision they're pointing toward fulfills the value. Finally, mentally project yourself out to age 80 (or your business out to 2 years from now) to determine which decision you would most regret not having made given your prioritization of the above values. That's the choice you should go with. Example.
- Allocate resources• Often, 80% of outputs originate from just 20% of inputs. So, prevent inefficiencies by allocating most of your resources toward the top 20%.
• Whenever you're about to make a critical allocation of time, money, or resources, list all the inputs being allocated toward the objective. Then, rearrange them in order of which produce the most outputs (e.g. revenue, products). Narrow in on the top 20%.
• That top 20% will shift over time, so re-analyze outputs at fixed intervals.
- Efficiency insightsTo free your mind of convention and analogy, you must systematically brainstorm ways to keep a system/process working when one of its components is removed. This model can be applied to every system (e.g. government) and every process (e.g. marketing) you encounter. Stay alert for opportunities:
1. Write a concise description of the system/process' objective.
2. List the fewest components needed to fulfill the objective.
3. Go through each component and ask, If I removed or replaced this, could I still fulfill the objective in any way? If so, generate a list of replacement scenarios. These are your potential insights. (To execute this step, you'll need intimate knowledge of each component's function. Consult experts and research as needed.)
4. Identify which potential insights are 1) high-leverage and 2) feasible. These are the winners. Example.
- Prevent problemsWhen you encounter a serious issue:
1. Iteratively ask, Why did this happen? Example.
2. Pause when you reach a cause you couldn't have prevented or for which a prevention would have been too broad to efficiently address the problem. Go one step back in the chain and ask, How could I have prevented this cause?
3. Using your suggested prevention as the new jumping off point, iteratively ask Why did/didn't I do this? to uncover how you failed to proactively implement this prevention. For each of your iterative answers, come up with a potential solution for it.
4. Use 80/20 analysis to determine which of the potential solutions is highest-leverage.
- Argument frameworkWhen someone presents an argument, consider using this framework:
1. Ask them to clearly state their conclusion.
2. Ask what premises ("reasons") lead to their conclusion.
3. Ask what evidence they have to support their reasons.
4. Check their conclusion against the ten fallacies. Refute any fallacies that exist.
5. If the argument still seems fishy, check their evidence against the three biases. Point out any that exist. Explain that any premises built on these biases must be re-examined.
- Debate guidelinesProductive debates share two goals:
1. Get at least one party closer to the truth.
2. Mutually improve the understanding of why each party thinks they way they do.
1. Opponents will pause and think before responding to avoid knee-jerk reactions.
2. Opponents will not introduce new arguments until prior ones have been addressed.
3. Opponents will cede their biases and fallacies whenever they're accurately identified.
4. Opponents will not repeat themselves if they were understood the first time.
5. Opponents will speak slowly and will not speak over one another.
- Debate your friends1. If you want to increase the number of people who can debate toe-to-toe with you, share this guide with them. The link is julian.com/argue.
2. One fun thing to do is debate someone who hasn't read this guide. Then ask them to read it before debating you again. Witness their critical thinking transformation.
3. If you record a great conversation and you obtain consent from all parties to publish it, tweet me a link to it so I can feature it!
🤔 Interesting in building muscle? Check out my Muscle Guide.