The pair were speaking ahead of the release of their new album You May Offend.
The Proclaimers have said Britain was “freer and more tolerant” a decade ago than it is today.
The duo – twin brothers Craig and Charlie Reid – were speaking as they return with their first album in four years, You May Offend.
Craig Reid told BBC Breakfast he suspects people are “self-censoring” these days to avoid offending others.
He said: “I think 10 years ago, this country felt maybe freer and more tolerant than it does today. I think the internet is probably a lot to do with it. I think people are self-censoring.”
Referencing people being visited by police for social media posts, he added: “If you have 60,000 people who get visits from the police because of what they put on the internet, some of it may be racist, some of it may be inciting violence, but some of it isn’t.
“I think people are more cautious about expressing themselves now than they were even a decade ago.”
Charlie added: “I think you have to speak your mind and if you’re in the public eye, you have to do it.”
Asked if there is no longer space for the “middle ground”, he said: “It seems to be the middle ground has fallen out. It appears to be from the internet, it’s all extremes.”
The brothers released their debut album, This Is The Story, in 1987 and You May Offend is their 12th.
They have sold more than five million records worldwide, with I’m Gonna Be (500 Miles), their best-selling single.
Asked if they had any advice for Oasis stars Liam and Noel Gallagher, who famously feuded for years, Craig said: “I wouldn’t give any advice to them, their relationship is their relationship.
“If Charlie and I had bridges to mend, probably we could.”
Charlie added: “We grew up in the same bedroom, the same classes at school, the same friends. For us it’s normal. I think twins probably usually are closer than other siblings.”
