Considering the fact that Factfulness by Hans Rosling is not a piece of fictional literature so much as it is a nonfiction analysis of contemporary society and our perceptions of it, many of the book's key points are expressly stated throughout the text. Even in the title, one sees the emphasis Rosling places on empirical knowledge rather than subjective perceptions. He is interested in "facts"—not the way we tend to subjectively read the world around us. One target throughout the text is the mass media and its preference for doom and gloom, not necessarily because the world is a bad place, but because people are more interested in hearing about what is going wrong than what is going well.
In fact, one of the recurring themes throughout the text is the fact that the world is actually improving rather than becoming a worse place to live. Similarly to Steven Pinker in his seminal book The Better Angels of Our Nature, Rosling draws our attention to how poverty rates across the world have actually decreased by half over the last twenty years alone. People, though, not being easily able to determine what is "factfulness" and what is not, struggle to see this, as they struggle generally to distinguish what is a reliable source of information and what is not.
This is another major theme throughout the text: that humans do not have a healthy enough skepticism for the sources of information they are exposed to. This is in addition to possessing a lack of healthy skepticism more generally. In Rosling's book, one could argue that people are nothing short of excoriated for their inability to adapt the scientific method to their daily life. Instead, people "generalize" (the sixth chapter is on generalization) and do not question the categories they put people and pieces of news in, creating what are ultimately irrational categorizations. He particularly challenges the notion that there is a divide between the developing and developed world—suggesting instead that no such bifurcation exists.
As Rosling says in his introduction, "Everyone seems to get the world devastatingly wrong." Factfulness seeks to prove this thesis and, in the process, shows us things may be better than we think.