Probably the most important strategy at work in deconstruction is the tracking down of hierarchical structured oppositions. According to Derrida, it has been a characteristic of the western philosophical and scientific tradition since the classical times to think in binary oppositions. Presence opposes absence, speech opposes writing, philosophy opposes literature, the literal opposes the metaphorical, the central opposes the marginal, life opposes death, the real opposes the imaginary, the normal opposes the pathological, etc. Derrida shows how one of the oppositional terms is always privileged, controlling and dominating the other (dominating 'the other'). 'In a classical philosophical opposition we are not dealing with the peaceful coexistence of a vis-à-vis, but rather with a violent hierarchy. One of the two terms governs the other (axiologically, logically, etc.), or has the upper hand' (Positions, p.41).
An example of a familiar philosophical opposition in which one of the terms controls the other can be found at Logos Above Writing. All examples used on this page are taken from 'Plato's Pharmacy' (Dissemination, p. 63-171).
 Derrida traces these hierarchically ordered binary oppositions and he radically questions the dominance of the privileged term by reversing the hierarchy. The opposition remains intact, but the attention shifts from the dominant term to the dominated term, from the center to the margin. Margins. The margins of philosophy. The margins of a text. To advance the margins involves many different operations, including making comments in between the lines, revealing what is concealed by the text, tracing any blind spots of the author, explicating subconscious presumptions in the text, bringing up hidden contents and intentions, paying special attention to footnotes, tracking words that harbor an unresolvable contradiction where one meaning is chosen above the other at one time, while reversing that choice the next time, shifting the attention from an author's main work to a small, unfamiliar and seemingly insignificant text, etc.
For an example, see Writing Above Logos.
 One should not, however, leave it at this reversal, because the oppositions are not undone by simply reversing them. To deconstruct the binary oppositions does not only mean to reverse them, for to simply replace the central term with the marginal is to remain locked in the 'either/or' logic of binary opposites. One should simultaneously take note of the breach that occurs in the reversing. During the third moment, the oppositions are unsettled. However, this is not done by stepping outside the oppositions, for example, by introducing a third term as a means of attempting a kind of dialectic approach. Rather, the task is to dismantle the metaphysical and rhetorical structures that are at work within the text, not in order to reject or discard them, but to reinscribe them in another way. (The entire structure of binary oppositions becomes particularly unstable and unravels in an infinite play in the so-called undecidables.)
 Deconstruction works with this double movement; it situates itself both inside and outside of previous categories and distinctions. Instead of claiming to offer firm ground for the construction of a new order or synthesis, it remains involved in or attached to the system it criticizes and attempts to displace (cf. Culler, p.150-1). Deconstruction operates within the terms of a certain system with the intention of having this system derail. It uncovers the contingent origin of the binary hierarchies, and it does so not with the purpose of providing a better foundation for knowledge, but in order to dislodge their dominance and to create a space that leaves room for difference, ambiguity, and playfulness. This does not mean that deconstruction would revert to indifference. It implies that the distinction between two terms can no longer be supported by or founded in the priority of one of the two. Deconstruction is not so much a nihilistic criticism than an articulation of other values (cf. Music, Deconstruction, and Ethics ) .