Even if those societal effects were true (there are studies for both sides, and especially the helmet opponents are usually very outspoken and even rude, to the point that they lose credibility), the important thing for me as an individual is not whether helmets lead other people ("the society") to cycle less, but what the effect is on me.
Personally I feel some chilling effect (sometimes I cycle without helmet, so some friction is certainly there). But it's not very strong.
On the other hand, I have never consciously experienced a difference in car driver's behaviour whether I wear a helmet or not.
And I certainly am not cycling in any riskier way when I'm wearing my helmet. If you do, you should really think about what you're doing.
>especially the helmet opponents are usually very outspoken and even rude, to the point that they lose credibility
They have to be, because they don't have budgets and per diems. The pro-helmet side makes a fortune from selling helmets. The anti-helmet side runs on passion - whether that passion is for the truth as they see it (or as experiment and study have shown), or simply 'government out of my cornflakes' libertarian rage.
The pro-helmet side in general has far louder bullhorns, regardless of what goes on in internet forums (which is one of the no-budget places you see anti-helmet people.) The anti-helmet people aren't passing laws and running public service messages on TV with their partially publicly-funded nonprofits.
Personally I feel some chilling effect (sometimes I cycle without helmet, so some friction is certainly there). But it's not very strong.
On the other hand, I have never consciously experienced a difference in car driver's behaviour whether I wear a helmet or not.
And I certainly am not cycling in any riskier way when I'm wearing my helmet. If you do, you should really think about what you're doing.