In response to John Medaille, I am aware of Hayek's argument. The apparent dispute arises because Hayek has a different definition of a priori and of empirical. This different use of terms was not, as I recall, ever addressed by Mises. The production, communication, and economization and use of knowledge were Hayek themes. While they were not ignored by Mises, he sought to fry other fish. In short, Hayek's ex post explanation of his interest in communication by means of markets and prices did not accurately convey to readers how Mises dealt with the issues with which Mises was most concerned. Perhaps more importantly, Hayek's critique of Mises -- if it can be called that -- was based on a misinterpretation of how Mises used the a priori, in my view. It is possible that I can find some literature on this in my files. But it is off the subject in any event. I have not claimed that Hayek was a disciple or best interpreter of Mises. I will not try to defend Mises against the charge, in effect, that Mises is an incompetent philosopher. So if that is your tactic, as it appears to be, I am not interested. This is not a list in philosophy. I will defend Mises against specific criticism but not against the vague charge that he was out of his league. In my view, your interpretation of "Mises's a prioris" is similar to your interpretation of his "logical structure of the human mind." You do not understand it. I am willing to try to explain both of these to you, if you have the patience. But if you will not let me get started by accepting that the subject matter of economics is economic interaction, I will not be able to do this. Of course, I am not saying that everybody in the world must accept this definition. People define things as they want to. However, this is the definition that Mises used. Since the reasoning you have criticized in Mises is derived from his goal of studying "economic interaction," it is no wonder that you don't understand the other concepts. I do not understand your distinction between speculative and practical reason and have no desire to receive a lesson in philosophy unless it is a very simple one. Your use of the term science is not clear to me either. Finally, I do not see much use in the definition that you attribute to Heilbroner. I find the terms in this definition -- societies, handle, and provisioning -- sufficiently vague to admit of all sorts of phenomena for which a value free investigation would be impossible. In any case, Heilbroner's definition is also off the subject. In sum, it seems to me that since I cannot get to first base on this issue, I would do better switching to another sport. But perhaps this message will help you see things differently. A brief note to John Womack. I am not sure that I get the gist of your question, but it may be about whether economic action can occur without the actor possessing an end (values). The answer to this question is no. Thus, "action in the absence of an actor's values" is not part of the subject matter of economics, as defined by Mises. Finally, I would note that while I agree with Doug MacKenzie that Mises was not concerned with static or stationary, equilibrium states except mainly as counter-factuals, neoclassical economists are often similar. The problem with some neoclassical economists, according to Mises, is that they forget or neglect the only useful purposes to which equilibrium models can be put. These forsaken souls mistake the equilibrium for reality and thus ignore acts aimed at producing knowledge and at communication and, therefore, at making adjustments to continuing changes in market conditions. How many fit into this category is difficult to tell. Mises did not ordinarily direct his criticism at particular individuals. Pat Gunning