There are three main types of ideas. For simplicity, I have called them Type I, Type II and Type III. What differentiates developed countries from Third World nations is that large numbers of Type II ideas have been trashed in favour of the scientific method. Each generation and place must derive different truths (that is, Type I ideas). For instance, in the 18th century thinkers would have written against monarchy. But in the 21st century, Type I ideas would aim at clarifying misconceptions about capitalism, because it is already understood that kings and queens are not appointed by God.
After a hundred years, capitalism might be understood as being fundamentally good, and the truths which will need to be communicated will become different. By then, we would have understood more about Type I and Type II ideas. Some ideas might transfer from Type I to Type II. That is how the world progresses: by trashing its bad ideas.
Type I: Ideas which are essentially correct.
Some ideas can be partly correct, and may need refining, such as Newton's laws which were refined by Einstein. But Newton was basically correct. Milton Friedman's monetary work would also fall into this category. Other ideas might have only been partially explored and may result in very powerful results in the future. That is why science is continually yielding more and more secrets of the universe. It is one's job as a student of truth to quickly recognize as many of these Type I ideas. The more Type I ideas one knows and the better one knows them, the quicker living standards improve.
Type II: Ideas which are essentially false.
These include things like the earth being flat, that communism is feasible, or that the Aryan or any other race of men (such as white, black, green or yellow) is superior to others. It is one's job to quickly identify the ideas of Type II category and to place them in the rubbish bin meant for these ideas, in one's mind. We should not forget to flush out this trash every now and then by repeating in our minds the arguments about why that idea was wrong.
Type III: Ideas which can never be proved to be right or wrong.
The typical example of this is the existence of God. Even if we go far into the past, we get stuck with something always, behind which is an impenetrable vacuum. Before the Big Bang, what was there, and who created all that energy which drives the world? Is there only one universe or multiple universes? These questions can only be answered through beliefs. As Voltaire said: "If there were no God, it would be necessary to invent him." Life is so difficult and trying at times that it is good to have a God to pray to. But we should be mainly interested in extracting from religion a deep, Type I truth.