Knowledge can be useless. Much of what we learned isn't used.

The most famous example of useless knowledge must be schools.

But before discussing why school isn't practical, let's first talk about when knowledge is practical. I use this simple formula to decide if something has high application:

The practicality of some knowledge = Its usefulness (quality) X Total chances I can apply it (quantity)

Simply put, if a piece of knowledge is useful, or it isn't very useful but can be used a lot, or it is both useful and can be used a lot, then it's worth learning.

Let's first talk about the usefulness of knowledge.

Because some knowledge is more valuable than others, we compare and pick those that benefit us the most.

For example, suppose you have two ways to solve an issue. If the second way is better, then if you already have a lot of knowledge about it (when/how to apply the second way, how to handle its side effects, etc.), it is better than you already know about the first way. In another situation, if the first way is more efficient, then having the knowledge about it will be better. How useful a piece of knowledge is depends on the situation you apply it to.

It would be best if you understand both solutions well, but since we have limited time and resources, the best we can do is pick what we think will be the most useful and learn in advance.

Knowledge's usefulness is a good factor that helps us pick what to learn. An equally useful factor is how much we can apply a piece of knowledge.

Let's have an example to illustrate that.

One skill that is useful but isn't used a lot is interview skills. Suppose "good interviewing skills" have 1000 units of usefulness, but you only use it 10 times in your whole life; then its practicality can be calculated as:

Good interview skills practicality = 1,000 x 10 = 10,000

In contrast, "good dishwashing skills" (by having better gloves, better cleaners, knowing which one should be cleaned first, etc.) may only have 1 unit of usefulness, but because you need to wash dishes so many times in your whole life (supposedly 10,000 times), you have 10,000 chances to use these dishwashing tricks.

Good dishwashing skills practicality = 1 x 10,000 = 10,000

Although these two skills have many differences, they give you the same value.

Next, let's talk about how we can increase the usefulness of knowledge or how we can find more chances to apply knowledge.

There are usually three steps in our learning:

1. We pick what to learn.

2. We learn.

3. We apply.

We usually pay the most attention to the second step, although it contributes the least to the practicality of our learning and takes the most of our time.

Comparing the impact of the second step to the first step is like "Doing the right thing is more important than doing things right." No matter how well or diligently you learn, as long as the knowledge itself isn't practical, it's impossible to make it useful.

For example, we got 10,000 units of practicality in the two examples above because, in their essentials, those 2 skills (interviewing and dishwashing) are practical. These two skills are either useful or can be used a lot.

That doesn't mean how well you learn isn't important. Two people who both invest in improving their interview skills can yield different results. However, although how well you learn is important, it's less important than what you pick to learn at first. Learning hard how to do dishes or interview on Mars won't bring you much.

How we learn is also less important than how we apply. All the most incredible people I met in my career share the same tendency towards action-oriented behavior. That doesn't mean they just do and don't learn. They learn, but what makes them different from the rest is their ability to output high-quality work, either because they learned a lot so now they can condense their knowledge and transform it into valuable outputs, or they learned just a little but know how to convert this humble knowledge into highly usable results.

I also met many smart people who read many books but can apply little. That doesn't mean we shouldn't read books; it's just that learning well without knowing how to apply is a huge waste.

That's why schools suck. Schools focus excessively on how well and hard we should learn, but give us little choices over picking what to learn, and talk little about how to apply knowledge in real-life scenarios.

Since we probably know enough about how to learn well, I will not talk about it. Instead, I will focus on the 2 steps that we often overlook: how to pick applicable knowledge and how to apply them.

So, how do you pick practical knowledge?

The most obvious way is to pick what you have plenty of chances to apply.

Being better at communicating, time management, and finance management are always worth it, because no matter who you are or what your job is, you always have chances to apply these knowledge.

The same goes for learning fundamental knowledge. For example, in math, learning operations (+, -, *, /) can never be a waste. These operators might seem useless to us when we first learn them. However, now, as adults, few still say learning math operators is useless because we use them so many now. Instead, what we see as useless is the more advanced math knowledge we learn in high school or university, which few people can apply in their lives.

Another way to not learn what won't be used is to ... learn less, and work more.

The more you work (by working overtime, being a freelancer, or having your side business), the more value you create, and the more you are rewarded. It's guaranteed that you will get more when you work more.

Learning is riskier than working because it's not guaranteed you will always be better the more you learn. Or you can, but the change can be very little. We can learn a lot of things but find no place to apply them at all.

Working can be risky, but it's rarer, which mostly only happens in venture environments like startups or investments.

By working more, you can also learn more. This is the best kind of learning, actually. What you learn from work usually has higher usability because the source of this knowledge doesn't come from theories but directly from your work, which makes it easier to be applied back to work later.

Of course, not every job teaches. To be better, we still have to take the risk of learning things we can't be sure we can use.

Besides picking those that are easy to apply, we can also pick those that are useful.

But what makes a piece of knowledge useful? To me, knowledge is useful when it is relevant to real-life applications. For example, knowledge that can improve your routines, work, and relationships is relevant and applicable.

But relatable knowledge can be boring. We prefer learning stranger things, which are usually more fun.

Novel knowledge is harder to apply, but they give us brilliant ideas whenever we can apply them.

"Because I had dropped out and didn't have to take the normal classes, I decided to take a calligraphy class to learn how to do this. None of this had even a hope of any practical application in my life. But 10 years later, when we were designing the first Macintosh computer, it all came back to me. And we designed it all into the Mac. It was the first computer with beautiful typography. If I had never dropped in on that single course in college, the Mac would have never had multiple typefaces or proportionally spaced fonts. And since Windows just copied the Mac, it's likely that no personal computer would have them. If I had never dropped out, I would have never dropped in on this calligraphy class, and personal computers might not have the wonderful typography that they do. Of course, it was impossible to connect the dots looking forward when I was in college. But it was very, very clear looking backward 10 years later." - Steve Jobs

You have to wait until the right moment to apply them. But even if that's the right moment, it's hard to convince everyone to use novel ideas.

It's unlikely that your boss will listen to you when you tell him you have this fantastic idea, but you have never tried it before.

Because applying novel ideas is risky, it's easier to apply them when you are in a position of authority, which can be either you being a boss, you being your own boss, or you are in an environment that allows risks.

Although novel knowledge is less likely to be applicable, learning it can be worth it, especially when you want to have glorious moments of wowing everyone (yourself included).

So, picking the right knowledge to learn impacts a lot on how you can apply them.

But what if you already learned something that's not usually applicable?

If you can apply what you learned to your work, then that's great!

But there are times when that isn't the case. Maybe because your work is already so easy that it doesn't need any improvements, or maybe because what you learn just isn't compatible with your work. It's rare that you can apply 100% of what you learned, but it's also rare that you can not apply even 1%. This means that even if what you learned isn't totally compatible with your work, you can still find places to apply it partially. Even just 1% is still better than 0%. But maybe 1% is too low for you. Then you always have the option to find another place, another company, that allows you to apply more.

Another way to apply more of your learning is to have side hustles. Doing your pet project gives you full authority over applying knowledge. You can learn anything and apply anything. You are basically a god.

However, although it's fun, teaches you many things, and can be put into your portfolio, side hustles do not have many visible benefits and don't guarantee that what you learned and applied here can be used in your real job. Also, there are few financial benefits from side hustles unless you convert your side project into a business.

Whichever you choose, it isn't easy. Although you have full control over what you learn, you have little control over your chances of applying it.

But learning only what's useful maybe isn't what you need. Perhaps you just want to learn for the sake of learning. Or you still want to apply more of what you learn, but not so much that you are willing to sacrifice something else.

For example, although we always dream about quitting our jobs, opening our own businesses, and having total freedom over how we apply knowledge, few people do so.

Not being able to apply what you have learned usually leads to three paths.

You may give up trying to apply them at all, or even worse, you give up learning, because although learning is still fun for you, you cannot see its usage.

Or you still learn but are not focused on trying to apply it anymore. You know that the right time will come, or you don't care if the right time will come or not. You believe the best you can do now is just to enjoy and learn your best.

Or you will continue trying to find more ways to make what you learn practical, knowing it is hard, but worth it.

Which path you walk on is up to you.