The article describes the construction process of Deductive Flexibility Test  considered a difficult deductive reasoning measure  and the research on correlations between fluency in difficult deductive reasoning and other cognitive abilities. The main goal in the research was to examine the relations between Deductive Flexibility Test scores and results of Raven's Advanced Progressive Matrices  fluid intelligence test. Additionally, the measures of the need for cognitive closure and

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... ogical understanding were included in the study. The results of the study revealed that Deductive Flexibility Test is a reliable instrument and thus can be used for research purposes. We found low or even no statistically significant correlations between the chosen variables. The directions of further research are discussed.