Preface second edition, 1949 
The structure of social action (1937)
                                    
“The solution of the most important problems of the theoretical social sciences in general and of theoretical economics in particular is thus, closely connected with the question of theoretically understanding the origin and change of 'organically' created social structures.”
Source: Investigations into the Method of the Social Sciences, 1883, p. 147
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Carl Menger 6
founder of the Austrian School of economics 1840–1921Related quotes
Gunnar Myrdal (1982, 265); as cited in: Carlson, Benny, and Lars Jonung. "Knut Wicksell, Gustav Cassel, Eli Heckscher, Bertil Ohlin and Gunnar Myrdal on the role of the economist in public debate." Econ Journal Watch 3.3 (2006): p. 534-5
Source: Fuzzy sets and fuzzy logic (1995), p. 312 as cited in: William Siler, James J. Buckley (2005) Fuzzy Expert Systems and Fuzzy Reasoning. p. 36.
                                        
                                        Frisch, (1946, p. 1), as quoted in: " Ragnar Frisch 1895-1995 https://www.ssb.no/a/histstat/doc/doc_199403.pdf." O. Bjerkholt, 1994. 
1940-60s
                                    
“The most important tool of the theoretical physicist is his wastebasket.”
                                        
                                        Told by P. Morrison 
Attributed in posthumous publications, Albert Einstein: A guide for the perplexed (1979)
                                    
Source: "Games with Incomplete Information," 1997, p. 136
Source: Social Costs of Business Enterprise, 1963, p. 186 cited in: Sebastian Berger and Mathew Forstater (2007) "Toward a Political Institutionalist Economics: Kapp’s Social Costs, Lowe’s Instrumental Analysis, and the European Institutionalist Approach to Environmental Policy". In: Journal of Economic Issues. Vol.XLI, No.2, June 2007. p. 539
                                        
                                        Lecture II : The Universal Categories, §3. Laws: Nominalism, CP 5.61 
Pragmatism and Pragmaticism (1903) 
Context: Philosophy, as I understand the word, is a positive theoretical science, and a science in an early stage of development. As such it has no more to do with belief than any other science. Indeed, I am bound to confess that it is at present in so unsettled a condition, that if the ordinary theorems of molecular physics and of archaeology are but the ghosts of beliefs, then to my mind, the doctrines of the philosophers are little better than the ghosts of ghosts. I know this is an extremely heretical opinion.