First principle thinking

A simple guide to using first principles thinking to solve problems

First principle thinking
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Part of a course I’m looking at mentions using ‘first principle thinking’, they explain the idea in a neat way and then move on without elaboration. A newsletter I read recently talked about first principles thinking too and it reminded me of a colleague asking a few months ago about how to apply first principle thinking, but I would not recommend their post. It’s missing a lot of stuff and has a lot of waffle, so I thought I’d write a version I would recommend and would read myself. 

Credentials: I learnt and applied first principle thinking in physics and engineering courses in University, and have practiced them in one way or another since. That’s all of my qualifications, however, and this is where my biggest disagreement with both other sources comes from, it’s not that difficult. Anyone can do it and apply it to just about problem. Let me explain. 

What is first principle thinking?

It’s a way of thinking to help you solve a problem. The idea is to question everything you know about a problem and get to its foundations, then, you can start working from scratch on a new solution, questioning and challenging existing assumptions as you build back up, hopefully to something interesting and new. 

By doing so you are not constrained by conventional wisdom or preconceived notions, instead you can try and carve a new path. When successful this is seen as creative and innovative. Good job.

woman in black long sleeve shirt using macbook
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How to think from first principles

Define the problem: It can be literally anything. A business challenge, a scientific inquiry, a job application, a new recipe, a habit you want to form, a feeling you want to express, a dish you want to wash, whatever. Think about it, then write down the problem. More detail is good if it’s a complex or serious problem, but a sentence works.

Break it down: Look at the problem and try to identify the fundamental actions or states that govern it. We’ll run through some examples in a moment if that sounds confusing.  

Question assumptions: Identify any assumptions or beliefs that are commonly held but not necessarily true and question them. You might end up asking yourself things that sound silly, ‘does two plus two really equal four?’ but do it anyway. 

Build back up: Rebuild your understanding of the problem based on the principles you identified and the assumptions you changed. 

Iterate: Test your new understanding, see, or think about, how well it would work in practice, and then refine your approach as needed through experimentation.

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Examples of first principle thinking

First principle thinking is useful when you’re stuck or you’re trying to do something new. This is why it's perhaps more common in technology, science, and entrepreneurship, because these fields want to try to iterate and improve. However, I say that it can be applied to anything, the question is more, should it? So I’ll work through some simple though entirely useless examples so you get the idea (and can see how simple it is) but just know you can apply the same method to problems that are bigger and or much more serious.  

Example 1: Making a cup of tea

Define problem: I’m bored of making tea the same way

Break it down: the fundamentals of making tea:

  • Boiling water is required to brew the tea.
  • Tea leaves or tea bags are needed for flavour.
  • A container or cup is required to hold the tea.
  • You might want milk or sugar. Or other additives if you’re a maniac.

Question assumptions: what am I accepting as true or taking for granted here:

  • Do you need to use a kettle to boil water, or can you use a different heat source? Is there a way to make that more interesting? 
  • Do you have to use tea bags or loose tea leaves, or can you try something entirely different, similar things like herbal ingredients or entirely different things like minerals or synthetic material?
  • Is a cup or mug the only suitable container, or could you use a more unconventional vessel?
  • Can you combine some of these assumptions and have a vessel that boils, brews, and flavours the tea all at once? 
  • Must you use hot water, or are there alternative ways to brew tea?
  • Could the tea come pre-sweetened or with milk already added? 

Build back up: Based on our principles and if we modify our assumptions, you might try to make tea without a traditional kettle, experiment with unique tea blends, use a different type of cup or explore cold-brewed tea.

Iterate: I’m not going to do any of this because I like my tea the way it is but you could, and then you could refine it and hopefully you’ll have more fun making or even make better tea.

clear glass mug on tray
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Example 2: Cleaning dishes

Define problem: I don’t have a dishwasher so cleaning dishes takes more time than I would like

Break it down:

  • I wash my dishes after I have finished eating
  • You need water to clean the dish.
  • You need a cleaning agent (soap) to remove grease and food stuff.
  • You need to physically scrub the dish to dislodge dirt.
  • You need to rinse again with clean water to remove suds.
  • You need to dry it to prevent water spots or dampness in the cupboards.

Question assumptions:

  • Does the dish have to be washed immediately, or can it wait?
  • It takes a long time because there’s a lot to wash, are there things you don’t need to wash? At least immediately? 
  • Must you use a traditional dish washing sponge, or are there alternative cleaning tools or methods?
  • Is warm water the only temperature that’s effective, or can you use cold water?
  • Do you need soap or can you find a natural cleaning agent?
  • Must you physically scrub the dish, or are there other means to remove dirt?

Build back up: Based on our principles and if we modify our assumptions, you might decide to wash dishes another time, to use a non-traditional cleaning tool like a brush, to experiment with different water temperatures and cleaning solutions to make it quicker, find recipes or dishes that don’t require constant washing up, and maybe explore other methods such as ultrasonic cleaning or even dishwasher use.

Iterate: If you build back up to something you like you could test your new approach, evaluate the cleanliness of the dish, the efficiency of your method, and the time it takes, and adjust your process as necessary. 

I thought this one would also be entirely silly (because I have a dishwasher, I’m not an animal) but I actually like the idea of looking for pans and recipes that go together so I don’t have to wash the pan every time, ones the retain flavour after being cooked … huh. Anyway. 

Example 3: Christmas gits

Define problem: I don’t know what to get my friend for Christmas

Break it down: 

  • I like gifts to be thoughtful and personal to the person.
  • It should express my appreciation for them.
  • The gift should align with the occasion, in this case, Christmas.
  • I don’t want to spend a lot of money

Question assumptions: 

  • Must the gift be a physical item, or could it be an experience, a service, or a donation?
  • Do you have to choose a gift based solely on what you know about them, or can you ask them what they want? Or consult mutual friends?
  • Does the gift have to be a surprise, or can you involve the recipient in the selection process?
  • Is it necessary to spend a specific amount of money, or can you focus on the thought and sentiment behind the gift?
  • Do you need to get them a gift at all? If it’s to show appreciation, why not say so?

Build back up: Based on our principles and if we modify our assumptions, you might conclude that you can consider gifting an experience of some kind instead of a thing. You might also/instead talk to the person to ensure the gift is something they want, or forgo spending money and tell them how much you appreciate them instead. 

Iterate: After selecting a gift think about how well it matches the person in your mind. Adjust as needed to ensure it expresses your care and consideration. Then, observe their reaction and make a note for next year. 

wrapped gift box
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Conclusion

Thinking in first principles isn’t hard, you might need to practise, but it’s not difficult. Maybe you can give some examples ago yourself, if you do, let me know how you get on. The problem people try to tackle can be hard, and deciding what problem you care enough about is hard, but first principle is thinking is easy. Give it a go.