At school and in many TVET programmes, textbooks generally present information as unquestioned, cut-and-dried facts. However, because environmental and sustainability knowledge (including the cultural aspects of this knowledge) is most often linked to issues means that this knowledge is contested; in other words, people disagree about its validity (truth). For example, despite what many people consider to be convincing evidence that human activities are causing global climate change, some people (and even governments!) believe that the changes we are witnessing are due to natural cycles only. Yet climate change is mainly about the impact of high levels of greenhouse gasses. These are due to anthropogenic (human induced) changes resulting from fossil fuels. This challenge intersects with natural cycles. It is therefore important to establish the ‘best available truth’, and not just support post-truth or false information that is often spread by denialists or because of vested interests. Educators have a responsibility to work with the best available truth in their educational programmes, without being dogmatic or ideological.
Furthermore, in many cases, we do not know enough about an environmental or sustainability issue. Our knowledge is incomplete, and thus uncertain. Most teachers and learners are unaccustomed to working with knowledge that is contested or incomplete. Yet this is an important feature of knowledge in the 21st century, hence we emphasis the idea of ‘best available truth’.