1) Usefulness 
[phrenology] ==Interaction with other faculties== ...
• (n.) Tendency or ability to form or construct. • (n.) The faculty which enables one to construct, as in mechanical, artistic, or literary matters.
Con·struct'ive·ness noun 1. Tendency or ability to form or construct. 2. (Phren.) The faculty which enables one to construct, as in mechanical, artistic, or literary matters. 
[n] - the quality of serving to build or improve
noun the quality of serving to build or improve