In many ways, the problem of cognition is as much a 'hard problem' and the problem of consciousness. What is cognition? Matthias Melcher looks at different answers to this question. If I had to answer, my first reaction might be 'cognition is thought', or 'the act of thinking'. But I might define it via 'invisibility', in Melcher's sense, as in 'cognition is that aspect of consciousness that isn't the subjective feel of consciousness'. In other words, 'cognition is thought that isn't experience'. But that to me reduces to saying there is no such thing as cognition. Best I have at the moment: 'cognition is the interpretation of consciousness' - that is, how we, as observers, explain the meaning or intent consciousness in other people, and by inference, in ourselves.