This tool makes it possible for a system admin to obtain information that might correlate installation of package dependencies with a package breakage in order to find which package update might be responsible for the breakage.
$ which-pkg-broke aptitude
Package <libapt-pkg-libc6.3-5-3.3> has no install time info
libdb1-compat Fri Aug 8 03:02:11 2003
libsigc++-1.2-5c102 Fri Aug 8 05:15:58 2003
aptitude Sun Jan 11 17:38:06 2004
libncurses5 Sun Jan 18 08:11:05 2004
libc6 Thu Jan 22 07:55:10 2004
libgcc1 Tue Jan 27 07:37:22 2004
gcc-3.3-base Tue Jan 27 07:37:31 2004
libstdc++5 Tue Jan 27 07:37:32 2004
So depending on exactly when the misbehaviour started, there may be a reason to point the finger at a more-recently updated library like libstdc++ or libncurses, which are more-recently installed than aptitude itself.
This manual page was written by Javier Fernandez-Sanguino for the Debian GNU/Linux distribution.