Not knowing that you don’ know is the worst possible combination of ignorance out of the four possible cases. If you know what you don’t know, the solution is easy; look it up on the internet or ask someone.
However, if you don’t know, you wouldn’t know what to ask and this in turn leaves a multitude of possible answers.
I know three solutions to this problem.
The first one is original thinking. This is incredibly hard. While I wouldn’t go as far as saying that there are no original thoughts (I’ve had a few myself in my lifetime), they are rare. Most original thinking comes from synthesizing knowledge from other fields.
This leads me to the second method: Studying. In many cases, what is unknown to you is not unknown to others. In addition we are blessed with an abundance of information and so simply reading enough may be sufficient to find gold. It must be kept in mind that one must deliberately read outside one’s normal “zone” for this to work. Otherwise, it’s just useless reinforcement. For example, you should never only watch one news channel and in particular you should NOT watch the news channel that matches your political orientation because the editor will filter out the things you need to hear the most.
The most common mistake is thinking oneself well-informed but having made the mistake of confusing quantity with quality, e.g. reading the same book over and over. This is particularly dangerous because it instills false confidence.
Studying also comes in a passive form. This third form is called advertising. Advertising works by repeating the same message over and over. People will pay attention to what is repeated most. This is sadly how most learn. Being passive you limit yourself to sources who prioritize hyping and creating buzz. Advertising is a science so by not being an active seeker, you limit your information sources to those who prioritize marketing.
Of the three solutions, the second one has most of the merit.
When I was working as a researcher we (and likely many others) had a saying: “Half an hour in the library will save a month in the lab.” This is a big reason why I have never cut my book/knowledge budget when I didn’t have better options available(*)—and why it’s very important to me to have good library options available. Trying to save $10 on something that will save you a month of work is just not good business sense. You save in the short-run but it’ll cost you in the long-run. The opportunity-cost of deliberate ignorance is very high.
(*) This is not entirely true. When I was beginning ERE in 2001, I did go for almost a year buying only one new book per month while not having access to libraries. That was a horrible time.
In fact, probably 90-95% of all research, that is, your own original thinking, consists of false starts and dead-ends. The “not invented here” attitude is simply not worth it. If someone has solved the problem already, don’t reinvent it, go for it.
Relying on buzz/advertising is the worst possible means of acquiring information. First of all, by definition, you have no control over what information is being delivered to you because advertising found you, not the other way around. Since the problem is (still) unknown to you, you have no context in which to judge it. At this stage the only way to connect the information to you is via simple emotional manipulation. I read a lot of book reviews and books with titles like “365 Secrets to be Remarkable like Superman in Just 21 Days” often sell really well yet, not surprisingly, at least to me, often get reviews like “doesn’t live up to the hype” and more pertinent “doesn’t live up to the title.” You’ll find the same problem with products sold on late night infomercials. What often holds is that while these products are presented as innovative, they really are not. It is more likely that they are repackaged material that already exists in a much better form—it is just an unknown unknown to you. For instance, here’s some sales copy from the 4 Hour Work Week which promises to show “How to eliminate 50% of your work in 48 hours using the principles of a forgotten Italian economist”. Unless you’ve been living under a rock you’d probably already know that we’re talking about the Pareto principle which is known to anyone with even the slightest interest in productivity since the 80/20 Principle which came out in 1998. This is where advertising can turn unknown unknowns into known unknowns, which can be dealt with using conventional methods.
To summarize: Your brain, your random reading, and advertising are three ways of turning unknown unknowns into known unknowns. In other words, they are ways of finding the right question to ask (whereas before you didn’t even know the question). However, they rarely produce the answer you need. For that, further study is needed.