Discussion is more convincing than standard, unidirectional messaging, but its interactive nature makes it difficult to scale up. We created a chatbot to emulate the most important traits of discussion. A simple argument pointing out the existence of a scientific consensus on the safety of genetically modified organisms (GMOs) already led to more positive attitudes towards GMOs, compared with a control message. Providing participants with good arguments rebutting the most common counterarguments against GMOs led to much more positive attitudes towards GMOs, whether the participants could immediately see all the arguments or could select the most relevant arguments in a chatbot. Participants holding the most negative attitudes displayed more attitude change in favour of GMOs. Participants updated their beliefs when presented with good arguments, but we found no evidence that an interactive chatbot proves more persuasive than a list of arguments and counterarguments.