But it is not just enough to be a critical thinker, or even to arrive with a point of view of one's own. One must have an independant knowledge base, against which to compare facts or alleged facts for veracity. And must be willing to both trust and distrust that knowledge base at the same time.
We can learn a lot about humanity and how they act and react, and about the world around us, by soaking up knowledge about historical and pre-historical events. There are issues however with history sources themselves. Sources closely associated physically or in terms of proximate time to events, can be loaded or pre-disposed for or against aspects of an event or theories about such events, which only the passage of time may temper. Further, having a lack of proximity to events, may yield an ability to be dispassionate about such events, but may also so detach the observer from the event(s), as to render the student incapable of connecting to the animus of the times. Thereby invalidating many assumptions made, because they exist in a vacuum of misunderstanding.
We have often heard that history is written by the victors, and the evidence certainly suggests the truth of this. And yet while the winners in any engagement have a vested interest in spinning the popular knowledge of any event in a fashion to favor themselves, the passage of time and the destruction of evidence, renders the recovery of the truth, harder and harder as the years pass.
Look to how completely the Amarna period and the reign of the Pharoah Akhenaten, was obscured by the actions of his successors.
Next we must consider that historians are despite all their lofty pedigrees, still just humans. Eager often for approval and accolades, and as subject to the fads of what is popular and unpopular in terms of historical publications and trendy styles of analytical and proto-analytical thinking as other persons. Likewise, there is also the issue of convention. Some folks are more than content to follow in the ruts of what has gone before. Now on its own, this is neither good nor bad. The issue, is that thesis must always be subject to critical analysis, lest one fall into the trap of accepting something simply because everyone always has.
Look how the view of George Armstrong Custer has changed over the years. From his heroism during the Civil War, his aggressive appearance to protect and advance his own ego through his career, through his demise at the Little Big Horn. And it hardly ended there. His widow devoted much of the rest of her life to presenting and preserving the image of Custer as a hero in the ensuing years. Was this truth ? In later (recent) years he was endlessly villified as a monster. And yet, these are trendy illustrations of an individual operating in a time and under situations which are naturaly relative to the world in which they move. In fact the truth is again, not so simple, he was all of these things and none.
Consider that the cretaceous boundary Iridium layer and the discovery of the Chicxulub crater, took many disciplines and experts years to add up to a concurrent theory of what occured and what it meant. Experts for at least a while stubbornly resisted the thesis even as information accumulated. Resisting such a new thesis is not wrong, nor is it right. Ideas do need to be questioned and evaluated, and if they are for a moment shelved, that does not mean they cannot be revisited and evaluated again and again. For a while, researchers pondered whether the Cretaceous event did indeed kill off the dinosaurs. Though later studies revealed it is not nearly as simple as that. It was closer to a Coup de Gras, in a process that was already under way. And even that is not a complete explanation.
In closing all I can say is that to understand the world and have a prayer at approximating real knowledge about something, one must martial their mind and efforts to know information from many sources. Too few sources tends to yield a vulnerability to innacuracy, filtering and the biases, known and unknown of the knowledge provider. Even when that knowledge provider means to provide undamaged information, a single source tends to be risky. When the provider intends to mislead, it only worsens the situation. As the knowledge base broadens, the dimensions of awareness widen and new revelations of understanding become possible.