Many of the ideas that emerged from the Enlightenment have become so central to modern Western thought that the movement has become associated with modernity itself. The foundations of modern liberalism, including pluralism, representative government, and protection of civil liberties, found their first real expression in the Enlightenment, through the thought of men like Locke, Montesquieu, Voltaire, and Beccaria. Additionally, the Enlightenment represented the emergence of a critical, rational worldview that subjected time-honored institutions and practices to scrutiny, providing an intellectual framework for social reforms. So, in highlighting the "pros" of the Enlightenment, we can find in the movement many of the intellectual foundations for what we view as good about modernity.
On the other hand, in searching for "cons," we can find the origins of what we might view as negative aspects of modernity. Even during the Enlightenment itself, many intellectuals, particularly in Germany, chafed against what they saw as the excessive rationalism of the movement. They found the mainstream of Enlightenment thought to be stifling and sterile, and their critique of this aspect of the movement would resonate with nineteenth-century Romantics. Others were troubled by the idea that human institutions could be reinvented, solely with reason as a guiding principle. Jonathan Swift and Edmund Burke, though separated by more than half a century, each expressed this concern. Finally, some modern critics have seen the Enlightenment as a force for order that borders on the tyrannical. Michel Foucault, for instance, has described the effects of the Enlightenment on categorizing and normalizing human behavior in a highly negative light. From a historiographical standpoint, modern historians have even begun to challenge the idea that a unified movement that can be described as the Enlightenment even existed in the first place.