Rather than consulting his own philosophical intuitions, Knobe set out to find out how ordinary people think about intentional action. In a study published in 2003, Knobe presented passers-by in a Manhattan park with the following scenario. The CEO of a company is sitting in his office when his Vice President of R&D comes in and says, ‘We are thinking of starting a new programme. It will help us increase profits, but it will also harm the environment.’ The CEO responds that he doesn’t care about harming the environment and just wants to make as much profit as possible. The programme is carried out, profits are made and the environment is harmed.

Did the CEO intentionally harm the environment? The vast majority of people Knobe quizzed – 82 per cent – said he did. But what if the scenario is changed such that the word ‘harm’ is replaced with ‘help’? In this case the CEO doesn’t care about helping the environment, and still just wants to make a profit – and his actions result in both outcomes. Now faced with the question ‘Did the CEO intentionally help the environment?’, just 23 per cent of Knobe’s participants said ‘yes’ (Knobe, 2003a).

This asymmetry in responses between the ‘harm’ and ‘help’ scenarios, now known as the Knobe effect, provides a direct challenge to the idea of a one-way flow of judgments from the factual or non-moral domain to the moral sphere. ‘These data show that the process is actually much more complex,’ argues Knobe. Instead, the moral character of an action’s consequences also seems to influence how non-moral aspects of the action – in this case, whether someone did something intentionally or not – are judged.〔; Knobe (2003b).〕