Philosophers like John Locke and Jean-Jacque Rousseau helped formulate ideas that would have a lasting impact on the tenets of democratic governments and modern science. When these two philosophers were writing, monarchies—no matter how cruel or inexperienced—were the prevailing government system in Europe. Locke and Rousseau proposed bold, liberal ideas that were adopted quickly by many radicals who used these beliefs to justify reform or revolution.
Perhaps the most crucial political theory Locke and Rousseau developed is the idea that humans are born with natural rights. Governments cannot take these civil, political, and cultural rights away. It is a government's job, according to these two philosophers, to uphold them. If a government is not protecting these rights, or if they are infringing upon them, then it is the responsibility of the people to change the status quo—either through election or force. These were pretty bold ideas for subjects in colonial America and France, who grew tired of corrupt kings who claimed divine rule as justification for their actions.
Locke's concept of self also helped form the basis for an Enlightenment-era scientific theory. Locke believed that we are born as blank slates and that we fashion a self through the knowledge we perceive through our senses. These ideas about consciousness and knowledge helped create an empirical science model where one gains information through observations of experiments and phenomena.