Logic

Logic in The Sims
Logic helps you advance in certain careers, although does nothing else. In the original Sims, the only way of increasing a Sim's Logic bar was to play chess, but with Livin' Large, the chemistry set and telescope was added, which are other ways of increasing the Logic skill.

Logic in The Sims 2
Once Open for Business is installed Logic points increase the rate a Sim gets badges for being a Cashier and Restocking items, it also affects the odds of winning a chess game.