He was commenting in an address to about 320 graduates who had just graduated from the University of Otago with a range of qualifications, including in law, commerce and health sciences, at a 1pm ceremony at the Regent Theatre, Dunedin, on Saturday.
''No matter what degree you have chosen, a university education teaches you one thing: how to think.
''The knowledge you have gained and the training you have had has given you the ability to make many decisions instinctively.
''I worry when we tout ourselves as a clean and green country,'' he said.
This message had ''instant appeal and short-term popularity'' but relied on ''confirmation bias'' and was ''doomed in the longer run''.
Discussing ''confirmation bias'' elsewhere in his address, Dr Rolleston noted ''we are often too willing just to take information we have been given to confirm our prejudice''.
• William Rolleston is a South Canterbury farmer and company director and is vice-president of Federated Farmers.