Working in the field of celestial mechanics, Laplace was an astronomer and cosmologist who analysed the consequences of the law of universal gravitation formulated by Newton. In verifying the close agreement between theory and observations, he opened the way for a better understanding of natural phenomena. Laplace's exceptional contribution is in transforming a way of thinking that was still being debated into a paradigm that he clarified, extended and consolidated.

Taking factual observations into account, The System of the World makes a remarkable synopsis of the physical knowledge and methodical research of the time. Convinced of natural limits to knowledge, Laplace sought to reduce the part all too conveniently attributed to chance so as not to unreasonably limit the part open to scientific scrutiny. This approach is still relevant today even though the purpose and rationality of science are sometimes called into question.

In the field of celestial mechanics, Laplace is the direct heir to Newton but he can also be considered as the heir to Pascal in the field of the calculus of probabilities since his work brought a new impetus to this discipline.

Laplace laid down the basic principles of the calculation of probabilities by introducing the concepts of correlation and stochastic convergence, reported on the law of large numbers, and developed, with Gauss, the method of least squares. He thus created a universal tool not only for the physical sciences, but also for other disciplines such as biology, economics and the human and social sciences.