Pretending to work: a closed world reasoning formalisation of pretend play Lisa Benossi Abstract: Pretend play is often defined as an imaginative play that involves acting as if : for example, pretending to work would be analysed as “acting as if one was working”. The question on how human beings understand pretence becomes particularly interesting, as soon as one realises that 24 months old children are able to engage in basics forms of pretend play. In the attempt to clarify what acting as if means, the present work deconstructs pretence in terms of simpler reasoning processes, i.e. the ones that children display when they start engaging in pretend plays. This deconstruction is guided by experimental results about imagination, hypothetical reasoning and pretence in early childhood. At the same time, the theoretical analysis of these imaginative phenomena is directed towards a logical formalisation of pretence. I suggest that the logic based on closed world reasoning – i.e. the treating of all the information not currently considered or represented as false – used in this work displays how imagination, subtractive reasoning and pretend play are related. Since autism is often diagnosed on the basis of a lack of pretence behaviour, part of the work is devoted to the investigation of how children with autism engage in pretend play. The union of psychological, philosophical and logical analysis, presented in this work, models the behaviour of both neuro-typical and children with autism, and generates a novel hypothesis on children’s understanding of pretence.