Do ontologies always support communication of their content among human agents?

CONTEXT: In the debate on information systems ontologies [ISOs], it is widely accepted that one fundamental feature of ISOs’ purpose is that they support and facilitate fruition, communication, and understanding of, as well as inference from, ISOs’ contents for human and artificial agents. OBJECTIVE: The paper aims to show that ISOs’ contribution to knowledge cannot always obtain, especially as far as human agents are concerned. METHOD: Firstly, we introduce two ISOs, each representing specific contents, different from one another, by means of distinct languages and assumptions. Secondly, we examine what a human agent with no knowledge concerning ISOs’ languages, assumptions, and contents could legitimately infer from both ISOs. RESULT: We prove that, despite the difference in ISOs’ languages, assumptions, and contents, a human agent may still make the same inferences from ISOs that adopt diverse rules of inference. This means that the contribution of ISOs to human knowledge is weakened as it does not affect the result of human inference. CONCLUSION: We conclude by arguing that for ISOs to be regarded as fundamental tools in supporting and facilitating human knowledge, it is necessary to consider ISOs’ languages, assumptions, and domains as external to ISOs’ contents.