antiperistasis

from The Century Dictionary.

• noun Antagonism of natural qualities, as of light and darkness, heat and cold; specifically, opposition of contrary qualities by which one or both are intensified, or the intensification so produced.
• noun In rhetoric, a figure consisting in granting what an opponent states as fact, but denying his inference therefrom.

from the GNU version of the Collaborative International Dictionary of English.

• noun Opposition by which the quality opposed asquires strength; resistance or reaction roused by opposition or by the action of an opposite principle or quality.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun philosophy The heightening of the force of an opposing process