Weekly I/O #32

Wrong but Useful, Birthday Paradox, Escaping the Old, True Priorities, Deliberate Habits

Cheng-Wei Hu | 胡程維
3 min readFeb 17, 2022

Weekly I/O is a project where I share my learning Input/Output. Every Sunday, I write an email newsletter with five things I discovered and learned that week.

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The below is extracted from the email sent on February 14, 2022

Here’s a list of what I’m exploring and pondering this week.

1. “All models are wrong, but some are useful.” — George Box 


I found the idea of something being useful but not necessarily right interesting. This quote resonated with me when Wittgenstein talked about Friedrich Nietzsche’s view on Christianity in Ludwig Wittgenstein: The Duty of Genius. From a psychological perspective, Nietzsche thinks that the critical point of Christianity is not whether it is true that there really is a God but whether belief in God can help us face an unbearable, meaningless life. In other words, if it is useful, it doesn’t matter whether the faith is true or not.

We can find a similar concept in the map as well. In the book, The Great Mental Models Volume 1: General Thinking Concepts, the author mentioned all the maps are flawed since a map has to be useful only if it’s the abstraction of reality. A map with a scale of 1 to 1 can be correct, but it will not be useful whatsoever.

2. Birthday Paradox: How many people do we need to have a 50–50 chance of at least two people sharing the same birthday? Only 23.

Article: The Birthday Paradox Experiment

Counterintuitively, in a room of only 23 people, the probability of at least two people sharing the same birthday is over 50 percent. Also, it only needs 60 people in a group to make sure that there’s a 99% chance of at least people having the same birthday. You can look up Wikipedia for a more detailed explanation or The Pudding to learn through an interactive experiment.

Thanks to Professor Juels for teaching this interesting paradox and Angelica Kosasih for sharing The Pudding website.

3. The difficulty of training one’s thoughts lies not so much in developing new ideas but in escaping the old.

Podcast: Investing and Life MasterClass w/ Guy Spier

Guy Spier mentioned this idea in the podcast, which is originated from Warren Buffet and Charlie Munger. Kevin Kelly also quoted a similar thing like “You are only as young as the last time you changed your mind” in the article 99 Additional Bits of Unsolicited Advice. I covered some bits in Weekly I/O #23.

I highly recommend anyone interested in Guy Spier to listen to this podcast episode. Even though they didn’t cover much about investing, it showcased how nice and humble Guy Spier is. I found his personality quite charming and seems to be rare compared to most other investors (judged by what I learned from the book Richer, Wiser, Happier).

4. Show me your calendar and I will tell you your priorities. Tell me who your friends are, and I’ll tell you where you’re going.

Article: 99 Additional Bits of Unsolicited Advice

Making new resolutions doesn’t work most of the time since our behaviors can easily fail to align with the priorities we set.

As quoted in Weekly I/O #8, “There are only three ways for humans to change: 1. change the time allocation; 2. change the place of residence; 3. change the people with whom they interact. Only under these three elements can human beings change. One of the most meaningless is: Make new resolutions.”

5. Make more deliberate habits rather than habits that result from accidents of history.

Book: The Almanack of Naval Ravikant: A Guide to Wealth and Happiness

We cannot deal with everything as we first encounter the situation. We need habits to function. However, there are a lot of habits we have that are the results of some accidents that we are not aware of how they are formed.

We accumulate all these habits. It’s important to be aware of how some habits are formed and unlearn some. For example, some habits might be a product of the desire trying to get our parent’s attention when we are toddlers. We should re-evaluate those habits and proactively cultivate habits that align with our current values to replace those old habits.

That’s it. Thanks for reading and hope you enjoy it. If you would like to receive the content every Sunday, sign up below 😎



Cheng-Wei Hu | 胡程維

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