Hobbes met Galileo in 1634 (when the former was 46 and the latter 70); this meeting precipitated one of the more significant conceptual transfigurations in the history of Anglo-European thought: the reinvention of political philosophy as a species of empirical science.
Under several metaphysical assumptions--collectively tantamount to materialism--Galileo endeavors to create a new science of physical motion.
The local/practical object of this science (mechanics) is to assign precise mathematical meanings to the terms mass, force, resistance, velocity, acceleration, etc. so as to permit analysis of physical events under necessary laws.
The global/epistemic object of mechanics is to derive from the representational system an experimental method whose deductive fertility is sufficiently rich so as to explain natural phenomena solely as necessary consequences of extrinsic relations among natural objects.
The metaphysical payoff of the new mechanics is a rejection of intrinsic (teleological) causality along with an overcoming of the inclination to regard event-chains as arbitrary sequences of phenomena.
The centerpiece of the new mechanics is the principle of inertia.
Under several metaphysical assumptions--collectively tantamount to materialism--Hobbes endeavors to create a new science of political motion.
The local/practical object of political science is to assign precise analytical meanings to the terms right, law, nature, contract, sovereign, etc. so as to permit analysis of political events under necessary laws.
The global/epistemic object of political science is to derive from the representational system an empirical method whose deductive fertility is sufficiently rich so as to explain civil phenomena solely as necessary consequences of extrinsic relations among political objects.
The metaphysical payoff of the new science is a rejection of psychological egoism along with an overcoming of the inclination to civil war.
The centerpiece of the new political mechanics is the principle of endeavor: the conatus.
In Les Mots et les choses, Michel Foucault contends that the "human sciences" (psychology, sociology, and literary criticism) were novel inventions of the nineteenth century: The epistemological field traversed by the human sciences was not laid down in advance: no philosophy, no political or moral opinion, no empirical science of any kind, no observation of the human body, no analysis of sensation, imagination, or the passions had ever encountered anything like man [as an object of empirical representation and concomitant scientific investigation] (The Order of Things, p.344). This view, in the context of Foucault's general historiography (i.e., archaeological method), is neither peripheral nor unargued; it is rather the culmination of some three hundred pages of close, painstaking historical analysis--all directed towards the conclusion that, during the nineteenth century, man "for the first time since human beings have existed and lived together in societies . . . became the object of science" (p. 345). Moreover, this emergence of the human sciences "cannot be considered as a phenomenon of opinion: it is an event in the order of knowledge" (p. 345).
While not implausible as a reading of Descartes' legacy, this staging of the invention of the human sciences in the nineteenth century distorts both past and present: it invites us to see radical breaks in intellectual history where there are none; it invites us mistakenly to characterize the early moderns as univocally and uncritically Cartesian.
By way of example, consider Foucault's analysis of the nineteenth century emergence of sociology-- a science projected, he says, on the surface of economics: "man appears as having needs and desires, as seeking to satisfy them, and therefore as having interests, desiring profits, entering into opposition with other men; in short, he appears in an irreducible situation of conflict; . . ." (p 357). This is not an exclusively nineteenth or twentieth century view; it is Hobbes in a nutshell, and while, more often than not, philosophers of the seventeenth and eighteenth centuries repudiated this view, it was no idle promissory note: it was (and remains) a thorough, comprehensive, robust representation of the human condition.