With Man a Machine, La Mettrie opposed Descartes on all fronts and asserted a combination of the mechanics of a single substance and matter in motion from Spinoza and Isaac Newton, with self love as the prevailing law and the quantitative difference that separates man from animal. He agreed with the idea of Locke that humans form ideas from associating sensations and believed that we could grasp our own cognition but that we did not know how we grasped it. To La Mettrie, the body controlled the mind - a mere effect of the body's working. La Mettrie's tediology postulated that the world has a reason for being and is going for some unknown goal and that man exists simply to exist without knowing the real reason. However, La Mettrie left many questions unanswered.
Helvetius introduced a higher rationality by which our competitive nature works for the higher good of society. He stated that the hidden hand of nature gave it a moral purpose, while our narrow view creates the war of all against all (Bellum omnia omnes). His idea of progress as the key to a better world was not to create something new, but to eliminate the errors of our world. Helvetius created his Rational Ethics (later dubbed Utilitarianism) which stated that there are only two motives: pleasure and pain. He postulated a society where self-love pushes us to maximize pleasure and minimize pain. He stressed that this society should only exist on the basis of the greatest good for the greatest number, this being best achieved by universal education and an enlightened legislation.
Diderotss dynamic nature told him that things do not just change; things change for the better. This novelist, art critic and editor of the most famous product of the Enlightenment, The Great Encyclopedia, saw nature as a totality of creative changes. Each of these changes reverberates through all of nature to maintain a constant newness. This view agreed with Diderot's idea of progress that concurred with Helvetius elimination of errors, but proposed that we should also expand and create new institutions. Diderot's psychology differed slightly from Lockess as he saw the mind as active, forming general ideas then using those ideas to create more knowledge and ideas.
The Baron d'Holbach's System of Nature applied the Mechanistic Materialism to the whole of nature and proposed that consciousness has the ability to produce a new order of reality broken down into three subsets; brute facts, social facts, and mental facts. d'Holbach thought it to be human nature to understand the world and act upon that understanding, such actions satisfied d'Holbach's notion of progress.
The Marquis de Concorcet's Sketch of Intellectual Progress popularized progress as a natural law and sketched the key to such progress to be the advancement of science and its application to government and social order. The first philosophé to call for gender equity, Condorcet also stated that history was moving towards a goal which would be the outcome of the application of reason, a sort of scientific utopia.
Finally, the Physiocrats seemed to set the class boundaries with their model of the French economy. To them, the problems of the economy lay within the parasitic, landowning aristocracy[ that seemed to serve no function but to hold the land. They thought the source of wealth flowed from the productive class, made up by the peasants, which they stated should be allowed to operate unhampered. The manufacturing class supported society with their goods. The Physiocrats coined the term LaissezFaire meaning to allow the economy to operate according to its own laws without alterations. They also first used capitalist, as they wanted to transform the countryside from the seigneurial to the entrepreneurial.