Why would the league fine Goldson $25,000 and Doucet only $10,000 when Doucet started their fight? The answer lies in how those players' actions were classified.
Doucet's fine was for unnecessary roughness. Goldson's fine was for fighting. Those violations carry different consequences.
Fighting carries a minimum $25,000 fine for first-time offenders, according to rules agreed upon by the NFL and its player. Roughness penalties carry lower minimums.
Doucet might have started the incident, but it wasn't a fight in the NFL's eyes until Goldson went after him.