“Razors” are rules of thumb that simplify decisions.

The most valuable razors I’ve discovered:

The Smart Friends Razor

If your smartest friends are all interested in something, it’s worth paying attention to.

If that something seems crazy, it's worth paying a lot of attention to.

The passions of the smartest people in your circles are a looking glass into the future.
The Rooms Razor

If you have a choice between entering two rooms, choose the room where you are more likely to be the dumbest one in the room.

Once you are in the room, talk less and listen more.

Bad for your ego, great for your growth.
The Man in the Arena Razor

It's easy to throw rocks the sidelines—it's hard to step into the arena.

It's lonely and vulnerable, but it's where growth happens.

When faced with two paths, choose the path that puts you in the arena—choose the path with real skin in the game.
The Feynman Razor

Complexity and jargon are often used to mask a lack of deep understanding.

If you can’t explain it to a 5-year-old, you don’t really understand it.

If someone uses a lot of complexity and jargon to explain something to you, they probably don’t understand it.
The Serendipity Razor

Some of what we call luck is actually the macro result of 1,000s of micro actions.

Your daily habits put you in a position where luck is more likely to strike.

When choosing between two paths, choose the path that has a larger serendipity surface area.
The Uphill Decision Razor

When faced with two options, choose the one that’s more difficult in the short-term.

@naval calls this making "uphill decisions”—overriding your biological pain avoidance instinct.

It's worth it—short-term pain creates compounding long-term gain.
The Rare Opportunity Razor

There is a rare class of opportunities that the average person will get 0 to 1 chances at in their lifetime.

They look scary, but have insanely asymmetric return profiles.

If you are fortunate to be faced with one of these opportunities, jump at it.
The Buffett Reputation Razor

“It takes 20 years to build a reputation and five minutes to ruin it. If you think about that, you'll do things differently.” - Warren Buffett

Your reputation is built over decades, but it's made of glass, not stone.

Remember that—act accordingly.
The Narrative Fallacy Razor

Humans are storytelling creatures—we weave together sequences of events to identify cause-and-effect when the reality is just luck.

When reading stories of success, it's fair to assume they downplay the role of luck as a contributing factor.
The Time Billionaire Razor

Time is our most precious asset.

When choosing between two paths, choose the path that places the highest appreciation on the value of your time.

This is not about money—it's about leverage.

The path where you spend more time in your Zone of Genius.
The Opinion Razor

"I never allow myself to have an opinion on anything that I don’t know the other side’s argument better than they do." - Charlie Munger

Opinions are earned, not owed.

If you can't state state the opposition's argument clearly, you haven't earned an opinion.
The Worrying Razor

If someone says "don't worry about it”—you should probably worry about it.

If you ask a question and the response involves an elevated voice, hand-waving, or scoffing—you should probably dig deeper on it.

"The lady doth protest too much, methinks."
The Boasters Razor

Truly successful people rarely feel the need to boast about their success.

If someone regularly boasts about their income, wealth, or success, it’s fair to assume the reality is a small fraction of what they claim.
Newton’s Flaming Laser Sword

If something cannot be settled by experiment or observation, it is not worth debating.

This will save you from wasting a lot of time on pointless arguments—on the internet and in real life.
Hitchens’ Razor

What can be asserted without evidence can also be dismissed without evidence.

The burden of proof regarding a claim lies with the one who makes the claim.

If unmet, no argument is required to dismiss it.
The Grit Razor

If forced to choose between two people of equal merit, choose the one that has been punched in the face.

The one who has been punched—metaphorically or literally—is likely to have true grit.

Applies to investing (founders), hiring (candidates), and more.
The "Look the Part" Razor

If forced to choose between two options of seemingly equal merit, choose the one that doesn’t look the part.

The one who doesn’t look the part has had to overcome much more to achieve its status than the one who fit in perfectly.

h/t @nntaleb
Hanlon’s Razor

Never attribute to malice that which can be adequately explained by stupidity.

In assessing someone's actions, we should not assume negative intent if there is a viable alternative explanation—different beliefs, lack of intelligence, incompetence, or ignorance.
The Optimist Razor

When choosing who to spend time with, prioritize spending more time with optimists.

Pessimists see the doors that are closed. Optimists see the doors that are open—and probably kick down the closed doors.

Remember: Pessimists sound smart, optimists get rich.
The Pygmalion Razor

The Pygmalion Effect says that high expectations lead to high performance (and vice versa).

When working with new people and teams, choose to see each individual as their highest potential self—they will begin to achieve more.

h/t @KatColeATL
The "What Stays the Same" Razor

It's difficult to predict the future.

Jeff Bezos famously said that investing in what might change is risky, but investing in what will remain constant is safe.

When building for the future, focus on the constants—focus on what stays the same.
The Crazy Idea Razor

If someone proposes a seemingly crazy idea:

(1) Are they a domain expert?
(2) Are they reasonable?

If yes on (1) and (2), you should take the idea seriously, as it may be an asymmetric bet on the future.

h/t @paulg
Those are 20+ of the most valuable razors I’ve discovered.

Follow me @SahilBloom for more threads on growth, business, and decision-making.

I will write a deep-dive on these razors in my newsletter. Join 66,000+ others and subscribe so you don’t miss it! https://t.co/qMB8i60ney
And be sure to check out my new podcast—Where It Happens—for deep dives with amazing guests on many of these razors, frameworks, and more. https://t.co/aZU12dSBIy
Since everyone is asking about Occam’s Razor, here’s the thread I wrote about it a while back!

Simple is beautiful. https://t.co/X8ZWwVKVlj

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**Thread on Bravery of Sikhs**
(I am forced to do this due to continuous hounding of Sikh Extremists since yesterday)

Rani Jindan Kaur, wife of Maharaja Ranjit Singh had illegitimate relations with Lal Singh (PM of Ranjit Singh). Along with Lal Singh, she attacked Jammu, burnt - https://t.co/EfjAq59AyI


Hindu villages of Jasrota, caused rebellion in Jammu, attacked Kishtwar.

Ancestors of Raja Ranjit Singh, The Sansi Tribe used to give daughters as concubines to Jahangir.


The Ludhiana Political Agency (Later NW Fronties Prov) was formed by less than 4000 British soldiers who advanced from Delhi and reached Ludhiana, receiving submissions of all sikh chiefs along the way. The submission of the troops of Raja of Lahore (Ranjit Singh) at Ambala.

Dabistan a contemporary book on Sikh History tells us that Guru Hargobind broke Naina devi Idol Same source describes Guru Hargobind serving a eunuch
YarKhan. (ref was proudly shared by a sikh on twitter)
Gobind Singh followed Bahadur Shah to Deccan to fight for him.


In Zafarnama, Guru Gobind Singh states that the reason he was in conflict with the Hill Rajas was that while they were worshiping idols, while he was an idol-breaker.

And idiot Hindus place him along Maharana, Prithviraj and Shivaji as saviours of Dharma.
I'm going to do two history threads on Ethiopia, one on its ancient history, one on its modern story (1800 to today). 🇪🇹

I'll begin with the ancient history ... and it goes way back. Because modern humans - and before that, the ancestors of humans - almost certainly originated in Ethiopia. 🇪🇹 (sub-thread):


The first likely historical reference to Ethiopia is ancient Egyptian records of trade expeditions to the "Land of Punt" in search of gold, ebony, ivory, incense, and wild animals, starting in c 2500 BC 🇪🇹


Ethiopians themselves believe that the Queen of Sheba, who visited Israel's King Solomon in the Bible (c 950 BC), came from Ethiopia (not Yemen, as others believe). Here she is meeting Solomon in a stain-glassed window in Addis Ababa's Holy Trinity Church. 🇪🇹


References to the Queen of Sheba are everywhere in Ethiopia. The national airline's frequent flier miles are even called "ShebaMiles". 🇪🇹
A brief analysis and comparison of the CSS for Twitter's PWA vs Twitter's legacy desktop website. The difference is dramatic and I'll touch on some reasons why.

Legacy site *downloads* ~630 KB CSS per theme and writing direction.

6,769 rules
9,252 selectors
16.7k declarations
3,370 unique declarations
44 media queries
36 unique colors
50 unique background colors
46 unique font sizes
39 unique z-indices

https://t.co/qyl4Bt1i5x


PWA *incrementally generates* ~30 KB CSS that handles all themes and writing directions.

735 rules
740 selectors
757 declarations
730 unique declarations
0 media queries
11 unique colors
32 unique background colors
15 unique font sizes
7 unique z-indices

https://t.co/w7oNG5KUkJ


The legacy site's CSS is what happens when hundreds of people directly write CSS over many years. Specificity wars, redundancy, a house of cards that can't be fixed. The result is extremely inefficient and error-prone styling that punishes users and developers.

The PWA's CSS is generated on-demand by a JS framework that manages styles and outputs "atomic CSS". The framework can enforce strict constraints and perform optimisations, which is why the CSS is so much smaller and safer. Style conflicts and unbounded CSS growth are avoided.