The Scientific Revolution and Enlightenment threatened monarchies because people began to examine governments, society, and began to want unalienable rights and a more democratic government.
Explanation:
The Scientific Revolution made people more interested in examining things, whether it was material science or society. It also allowed the Enlightenment to begin, where people wanted a fair society with unalienable rights and democracy.
These popular ideas were against monarchies and people began to oppose monarchs, threatening monarchies in Europe.