To go against can imply standing up to group norms or popular opinion. He's brave to go against public opinion for what he believes is right.
Pro Tip 2/3
Potential Consequences
Using 'go against' acknowledges potential risks or backlash from opposing something. If you go against the company policy, you might face severe consequences.
Pro Tip 3/3
Strength of Opposition
The phrase can indicate a firm determination to resist or challenge. She's determined to go against the odds and succeed.