Realism was treated as a conceptual claim for much of the late 20th century due to H. L. A. Hart's misunderstanding of the theory. Hart was an analytical legal philosopher who was interested in conceptual analysis of concepts such as the concept of 'law'. This entailed identifying the necessary and sufficient conditions for the use of the concept 'law'. When realists such as Oliver Wendell Holmes pointed out that individuals embroiled in the legal system generally wanted to know what was going to happen, Hart assumed that they were offering the necessary and sufficient conditions for the use of the concept 'law'. Nowadays, legal theorists tend to recognise that the realists and the conceptual lawyers were interested in different questions. Realists are interested in methods of predicting judges with more accuracy, whereas conceptual lawyers are interested in the correct use of legal concepts.