 The fourth season concludes with Arthur visiting a psychiatrist and recalling via flashback a disturbing encounter with his dad (Ben Stiller) that may explain Arthur s abrasive personality. Carrie and Doug decide to "validate" Arthur in everything he does. This leads to Carrie visiting the psychiatrist, who also has a flashback that makes her doubt her personality. Which leads Doug to also visit the psychiatrist and has his own flashback that makes him learn something about himself.