Man a Machine, is a work of the Enlightenment that was very much shaped by the breakthroughs of the Scientific Revolution. We should note that there is a certain scientific pragmatism to La Mettrie's approach, given how he claims to eschew abstract speculation. That being said, we should recognize that La Mettrie was a product of the eighteenth century, and that much of the science of his era has since been debunked by the centuries of work which has followed. Additionally, we must factor in the degree to which he himself accepted certain assumptions common to his time period. For example, consider his thoughts on gender and his assumptions as to the existential and biological differences between the two sexes (like many people during the Enlightenment, he distinguished between the rational male and sensitive female).

Probably the core, most important claim that shapes this book, is that human existence is primarily materialistic, as opposed to dualistic or idealist. In fact, he views human beings as a kind of biological machine (the vision of human being as machine is, in fact, written into the title of this work). For La Mettrie, human beings ultimately amount to another form of animal, more intelligent or advanced, perhaps, but of the same essential nature.

However, for all that he disdains the purely abstract and speculative (and for all he detests the theological), it should be noted that his entire vision of nature and humankind has an implied element of teleology to it (perhaps not the divine teleology which a Theist might assume, but there remains a rational functionality and intelligibility embedded across La Mettrie's vision of nature). Consider his use of language: his chosen metaphors tend to be constructs: clocks, machines—these examples tend to serve a function, which they are created to fulfill. Furthermore, consider his vision of nature, by which all creatures act according to some kind of reciprocity. Indeed, he reasons that there exists a Law of Nature, which functions largely in line with the Golden Rule. In pursuing these subjects, however, La Mettrie engages in the same kind of abstract supposition he claims to disdain.