Logic

The Sims
Logic helps you advance in certain careers, and also to cast spells or perform other magical acts. 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.

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