How illiterates interpret syllogistic problems Gustaaf Haan Abstract: In this thesis I have tried to find an explanation for the difference between literate and illiterate people in solving syllogistic tasks. I have formulated a list of experimental tasks designed to test a range of existing and new theories on this question. I interviewed over 23 illiterate subjects. The results are in some sense more puzzling than expected. They provide interesting new clues compared to the existing data from earlier research, and they falsify all (my) hypotheses. In chapter 4 I therefore come up with a new hypothesis, conjecturing that illiterate people do not impose constraints on verbal information of a theoretical nature. These constraints are needed to enforce new information beyond the information given, when two or more pieces of information are integrated. Only a lack of such constraints can explain the explicit inconsistencies encountered in the transcripts.