In this paper I present an examination of three six year-old children’s interaction with a task intended to
encourage reasoning and collaboration in number. A case is made for the importance of deductive
reasoning in supporting inductive reasoning and for the potential of hypothetical deductive reasoning in
supporting concept reification in early number. The children’s discourse is analysed using a framework
based on opinion/belief, plausibility and deductive reasoning schema in relation to the functional use of
actuality and modality linguistic terms. The analysis suggests that the children were able to transition to
deductive reasoning and this was reflected in their discourse through a shift to modality, and that this
shift suggested a sense of authority by the children in validating their thinking.