age of reason

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An era during which rational thought is prominent or esteemed, especially the Enlightenment in western Europe.
• noun An age at which a person is considered capable of making reasoned judgments.

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

• noun Roman Catholic theology Seven years of age, at which age a person is morally liable for the sins that he or she commits.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a movement in Europe from about 1650 until 1800 that advocated the use of reason and individualism instead of tradition and established doctrine