Laffer curve rates (for example, in the United States by the Congressional Budget Office). While the interaction between tax rates and tax revenue is generally accepted, the precise nature of this interaction is debated. In practice, the shape of a hypothetical Laffer curve for a given economy can only be estimated. The relationship between tax rate and tax revenue is likely to vary from one economy to another and depends on the elasticity of supply for labor, as well as various other factors. Even in the same economy, the characteristics of the curve could vary over time. Complexities such as progressive taxes
Ibn Khaldun scholars is increasingly common. Influential British historian and international affairs specialist Arnold J. Toynbee has called Ibn Khaldun's Muqaddimah "the greatest work of its kind." Ernest Gellner, once a professor of philosophy and logic at the London School of Economics, considered Khaldun's definition of government the best in the history of political theory. More moderate views on the scope of Ibn Khaldun's contributions have emerged. Arthur Laffer, for whom the Laffer curve is named, acknowledged that Ibn Khaldun's ideas, as well as others, precede his own work on that curve. A focus on understanding the nuances of Ibn Khaldun's contributions