Gödel's second theorem

Gödel's second theorem

[¦gərd·əlz ‚sek·ənd ′thir·əm]
(mathematics)
The theorem that any formal arithmetical system is incomplete in the sense that, if it is consistent, it cannot prove its own consistency.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.