Throughout the book, Foster makes a consistent argument for the importance of critical thinking, healthy skepticism, and avoiding an overreliance on authority. These principles have a long history in Western thought. In Ancient Greece, the philosopher Socrates taught his students by engaging in critical dialogues and asking probing questions in order to uncover logical flaws or false assumptions in their thinking. Socrates would often also engage in a dialogue with someone who was considered an expert on a given topic, gradually uncovering errors in that person's reasoning. These practices laid the groundwork for centuries of critical practices and remain very similar to the process Foster advocates for in his book.
The invention of the printing press (15th century) and (slow and gradual) increases in levels of literacy over the centuries that followed were also important factors leading up to a point in time where it would be necessary for Foster to write this type of book. When manuscripts had to be written by hand, they were understandably very rare and expensive; when it became possible to print texts (which included early ancestors of nonfiction such as political pamphlets) and distribute them fairly cheaply, individuals were able to access a much wider range of information—and also to be subject to more potentially false information.
These types of changes also played a role in some changes in attitude towards authority figures, often religious or political leaders. In 1517, Martin Luther launched the Protestant Reformation by challenging the absolute authority of the Pope and the Roman Catholic Church. While the rise of Protestant faith certainly did not endorse purely free thought (substituting one doctrine for another), it did raise an important challenge to the idea that individuals should have absolute faith in a single source of authority, and it argued that individuals should have access to reading and understanding scriptures themselves, rather than relying on someone else's interpretations. Later political events, notably the American and French Revolutions, also put a strong emphasis on challenging false arguments made by those in positions of political power and advocating for individuals to rise up and think for themselves. Nonfiction writings by philosophers and political writers also played an important role in disseminating the ideas that led to these political movements.
The Enlightenment and Scientific Revolution are also important contexts for Foster's belief in critical, skeptical thinking and the need for objective evidence. French philosopher René Descartes put a strong emphasis on rationalism and the human mind, placing rational thought at the core of what it means to be human and deeply influencing future thought and systems of education. Other thinkers built on this notion of inherent rational ability to make arguments for different political systems, including democracy, increased access to education, and the possibility of more widespread rights and freedoms. These shifts helped to create the world that Foster surveys in the second decade of the 21st century: a place where it is possible for people to hold many different viewpoints and opinions, and due to the rise of technology, share those views with an ease that has never been possible before. However, this proliferation of ideas has also made it harder and harder to discern what is true and trustworthy, hence Foster's decision to write his book.