The nature of curriculum problems has been identified as uncertain practical. The uncertainty of curriculum inevitably suggests the necessity of searching curricular certainty in its own way. That is to analyse language which closely connects individuals(subjects) with life-world(objects). ‘The Practical’, asserted by Schwab and his followers, is a language for curriculum which represents the uncertain practical nature of curriculum problems. The question investigated in this study can be specified as follows: seeing in the light of the meaning of the uncertainty, how should ‘The Practical’ be interpreted to improve the traditional way of thinking about curriculum? And how can this reinterpretation be asserted? ‘The Practical’ should be understood not as technical or instrumental rationality, but as critical rationality. It is based on phenomenology and hermenuetics and it exceeds their limitations. That is, ‘The Practical’, as a kind of critical rationality, is reinterpreted in the perspective of ‘critical rationalism’. Technical rationality has set limitations on the method and scope of human thinking and has emphasized the instrumental way of problem-solving. But in the reconstructive perspective of critical theory, ‘The Practical’ can be reconstructed as critical rationality which implicates self-reflective action. And the philosophical nature of ‘The Practical’, having been lost by technical rationality, can be recovered by critical rationality. In conclusion, ‘The Practical’ is a kind of rationality which emphasizes “problematizing” thinking as well as “problem-solving” thinking. This study has an implication on understanding curriculum. That is, taking the nature of curriculum problems and the reunderstood meaning of ‘The Practical’ into consideration, what has the phenomenon of curriculum been identified with and how should it be identified?