Emerging from amongst the parochial and savage child-rearing practices promulgated during the Dark Ages, John Locke's expansion of the metaphor of the child as "tabula rasa" (or, literally, "blank slate") forms what is popularly regarded as one of the earliest empirical attempts to understand the psychological processes of intellectual and emotional growth experienced by humans during early childhood. This new branch of scholarship enthralled a public hungry for knowledge as the roots of the Enlightenment flourished in the rich, intellectual medium of the late Renaissance universities. Unbeknownst to Locke, newer and more complex branches of scholarship would emerge from his thinking; his ideas would become a cornerstone in the foundation of modern studies in early childhood development.
According to both secular writings and Catholic Church records dating from around the 8th and 9th century, the idea that children are born into a world infected by "original sin" was a world view actively promulgated by church authorities. This worldview was reinforced by the barbaric, medieval dispensation of justice that was carried out by almost every European monarchy as a duty charged to them by the church. Monarchs wishing cull favor from the religious authorities were compelled to actively search out heretics. And indeed, monarchs were required to obey church orders or risk excommunication or execution.
As part of this feudal belief system, parents were encouraged and expected to literally "beat the devil" out of their children, in keeping with scriptural doctrine inspired by the biblical epic of Noah. The belief was that children were born into and part of an evil universe and therefore were themselves evil by nature.
However, the early 15th century saw the election of Pope Leo X. His corrupt practices and hedonistic excess led the church into the chaos of the Protestant Reformation. Until that time, scripture, laboriously inscribed by hand on parchment, and only in Latin, was accessible exclusively to the educated ruling elite. Armed with the newest technology of the day— William Caxton's printing press — Martin Luther published a translation of the bible in German. Soon, a flood of translated Bibles spread across Europe. The Bible was no longer inaccessible to a public illiterate in Latin, and splinter denominations of the Catholic Church began generating a wide spectrum of biblical interpretations, some of which diverged quite far from traditional doctrine.
These historical threads of change converged in the late 16th century and culminated in a new era known as the Enlightenment. Fed by new trends in intellectual freedom and no longer constrained by parochial politics, philosophers and thinkers across Europe began to freely explore ideas and topics without fear of censure by the church, embracing the fruits of post-renaissance scholarship. It is within this intellectual upheaval that John Locke published his watershed work, "Essay Concerning Human Understanding".
Within this paper, Locke considered that infants are born into the natural world as psychological blanks slates —the so called "tabula rasa", a metaphor first coined by the scholar Saint Thomas Aquinas three-hundred years earlier—with no pre-deterministic tendencies toward "good" or "evil". In this context, the caliber of an individual's character is implicitly determined by the sum of that person's experience; and, particularly, according to Locke, the quality of an individual's education is a pivotal determiner of the type of person those experiences produce.
Though widely embraced as a defining moment in the development of empirical developmental psychology, the publication of that paper produced prodigious amounts of criticism and rebuttal. For, as many opponents of his ideas so vociferously pointed out, Locke had neither carried out carefully controlled experiments to verify his theories, nor was he even a father.
Perhaps the most important result of John Locke's publication of his "Essay Concerning Human Understanding" is that it established the field of cognitive developmental theory itself as a scholarly blank slate. Others, particularly Emmanuel Kant and Jean-Jacques Rousseau, would later publish works purporting that nature imbues man with certain predispositions, giving rise to the concept of "nature versus nurture" as a framework upon which to build further cognitive development ideas. This seminal concept became the central underpinning for modern concepts of early childhood development; concepts that are, in their complexity and descriptive capacity, far more advanced and powerful than anything those early thinkers could conceive.
