The amount of knowledge we generate and store is growing exponentially. Much of what you learned in school or in the early years of your work has likely changed. It takes a little effort to stay up to date. It costs a lot to stay behind.
The speed at which you need to make decisions has accelerated. This begs for getting your hands on reliable information and knowledge fast. Fortunately, there are also many more ways to gain insights and the skills today. It takes little effort to stay up to date.
But you score no points for trying, effort is a means to an end. The outcome is learning and improving and you demonstrate that through using your knowledge in practical applications or as a building block for a model of thinking that can serve in sorting out problems.
How do you know?
Much to remember, not enough time. In a 2018 lecture, Alessandro Barbero outlined the difference between memory and history. The topic is complex, but we can make a high-level distinction:
Memory is individual, it's the point of view of one person.
History is the understanding of what happened from all points of view.
In 1996, Barbero received the Strega Prize, the most prestigious literary prize in Italy, and in 2005, the Republic of France awarded him the title of Chevalier de l'ordre des Arts et des Lettres. He is a historian.
You're likely under the impression that the study of history is a dry series of data points, with the occasional bright spot. That is before you listen to one of his hour-long lectures on any topic.
One you do, you know that reasoning on what happened, all the people who were involved at the time and what they were thinking is the highly engaging. The hour just flies. You don't get to it in school — too much ground to cover, too little time.
Yet, this is why history is important. Reality its complex. To understand what actually happened, a view of the events from above is critical. One of the ways to learn from the experiences of others is to get out of a personal point of view, widen the gaze. This is what history does.
Because it's the sum of all the things that happened to human beings, history answers the question: What really happened? Memory is important, but by its very nature is limiting. It takes into account only one point of view.
In the same ways as it's become difficult to stay up to date on everything, so is teaching and studying history. More things happened and more people were involved. More information is accessible today, but you have a harder time telling which one is the official version and why.
Reality is complex, yet there's a simple way to get good maps and directions: How do you know? Proof can mean a direct citation of a person or document that creates the genealogy of an idea, data point, or statement. Then you go from there.
What are consequences?
Sorting wheat from chaff comes next. In a 1964 lecture, Richard Feynman described his method:
In general, we look for a new law by the following process. First, we guess it... Then we compute the consequences of the guess, to see what, if this law we guess is right, to see what it would imply and then we compare the computational results to... experience, compare it directly with observations to see if it works...
In that simple statement is the key to science. It doesn't make any difference how beautiful your guess is, it doesn't matter how smart you are, who made the guess of what his name is... If it disagrees with the experiment, it's wrong. That's all there is to it.
The rigor you use to evaluate the consequences of decisions is what matters, this is the scientific part. The process that produces decisions may look scientific, but may not be. Value of the solution is what matters.
As you decide based on the understanding of something that happened, it's also useful to know that at some point in the past there were different rules. For example, if you spoke to an ancient Greek about democracy, they'd tell you that it means everyone in the city goes up a hill and votes right there and then on an issue. Every citizen (well, except women...)
One more reason to insist on understanding context.