I have been trying to say this in more ambiguous terms for a few months now, but Derrida says it much clearer in one of his books on the sign. His point here is basically that scientific literature, though it portrays itself as an objective discipline separate from metaphysical and theological tendencies, actually enacts such movements in its language (i.e., science is ethnocentric).
Note on terms: The epoch of the logos is the history of Western thought, which has articulated writing as secondary to speech in terms of constituting meaning. Whereas, for instance, if one says something to oneself, one cannot be uncertain of one’s meaning, if one picks up a book, one has a lot of work to do—and one can never know for certain an author’s intention. Speech (especially internal speech, talking to oneself) has, therefore, been thought as a quintessential “giver” or “maker” of meaning, and writing has been thought to merely represent speech, whereas speech represents, full, meaning. So writing becomes a “mediation of mediation,” a mediation of speech which is a mediation of meaning. A sign is something that stands in for something else in its absence, according to this history. A sign is composed of a signifier and a signified. A signifier is the thing that represents (for example, the word “tree” represents a tree and therefore is a signifier of tree), whereas the signified is the thing that is represented (the word “tree” signifies a tree, which is the signified). Science simply perpetuates this idea of the sign to its most extreme conclusion—and is a technique deriving from a metaphysical distinction.
"The epoch of the logos thus debases writing considered as mediation of mediation and as a fall into the exteriority of meaning. To this epoch belongs the difference between signified and signifier….And this distinction is generally accepted as self-evident by the most careful linguists and semiologists, even by those who believe that the scientificity of their work begins where metaphysics ends."
—Jacques Derrida, Of Grammatology, 12-13