Suggesting that the person who is making the argument is biased or predisposed to take a particular stance, and therefore, the argument is necessarily invalid.
Examples:
- Salesman: This car gets better than average gas mileage and is one of the most reliable cars according to Consumer Reports. Will: I doubt it—you obviously just want to sell me that car.
Synonyms: appeal to bias, appeal to motive, appeal to personal interest, argument from motives, conflict of interest, faulty motives, naïve cynicism, questioning motives, vested interest