You are able to detect falsehoods with your knowledge rather than your social cunning.
Benefit: Whenever you wish to detect whether someone is lying, if they are speaking about a topic which is encompassed by a knowledge skill in which you possess 7 or more ranks, you may use that Knowledge skill in place of the Sense Motive skill in order to determine whether or not they are lying. This Knowledge check is opposed by the suspected liar’s Bluff check and all normal modifiers for the lie’s believability apply. If you beat the liar’s check by 5 or more, you also determine whether or not the liar knows the truth about the topic they are speaking of, or whether they are merely fabricating something without knowledge of the truth.
Undefeatable: The Collected Feats Sourcebook, Copyright 2009 – 2010, Louis Porter Jr. Design, Inc. Undefeated, Copyright 2011, Louis Porter Jr. Design, Inc.