The critical arguments of scepticism lead to the conclusion that no proposition can be justified as true. The attempts to define knowledge as justified true belief therefore fail, even within externalism. If we attribute knowledge to someone else, we can never justifiably know that we have done it correctly. Attributing knowledge is a hypothetical activity. Moreover, knowledge itself is hypothetical as well. There are no justifiably identifiable good reasons telling us that an investigated proposition is true. Scepticism thus leads an optimist, who holds that knowledge exists, to objectivism, i.e. to the view that knowledge is objective because its truth can be reduced neither to good reasons nor to the beliefs of investigators. Keywords: scepticism, objective knowledge, internalism, externalism, objectivism