Is logic infallible and why ?

There are some people and things that do not act logically or feel logically. Logic is fallible it cannot account for that which is not illogical. As an example, consider when a computer plays a person in chess. The only way that a person can beat the computer in chess now is by playing in an illogical way. The computer can lose because it does not consider what is illogical, only what is logical.