“One advantage of exhibiting a hierarchy of systems in this way is that it gives us some idea of the present gaps in both theoretical and empirical knowledge. Adequate theoretical models extend up to about the fourth level, and not much beyond. Empirical knowledge is deficient at practically all levels.”

Source: 1950s, General Systems Theory - The Skeleton of Science, 1956, p. 197: Opening sentences

Philosophy and Real Politics (2008).
Philosophy and Real Politics (2008)

Oscar Iden Lecture Series, Lecture 3: "The State of Individuals" (1976)

Postscript to review https://www.hedweb.com/lockwood.htm of Michael Lockwood's Mind, Brain and the Quantum, BLTC Research, Dec. 2016

Source: 1950s, General Systems Theory - The Skeleton of Science, 1956, p. 200

Die Scheu vor der Spekulation, das angebliche Forteilen vom bloß Theoretischen zum Praktischen, bewirkt im Handeln notwendig die gleiche Flachheit wie im Wissen. Das Studium einer streng theoretischen Philosophie macht uns am unmittelbarsten mit Ideen vertraut, und nur Ideen geben dem Handeln Nachdruck und sittliche Bedeutung. <br class="br">Vorlesungen über die Methode des akademischen Studiums ( Seventh Lecture http://www.zeno.org/Philosophie/M/Schelling,+Friedrich+Wilhelm+Joseph/Vorlesungen+%C3%BCber+die+Methode+des+akademischen+Studiums/7.+%C3%9Cber+einige+%C3%A4u%C3%9Fere+Gegens%C3%A4tze+der+Philosophie,+vornehmlich+den+der+positiven+Wissenschaften), Friedrich Wilhelm Joseph von Schellings sämmtliche Werke, V, 1859, p. 277 http://babel.hathitrust.org/cgi/pt?q1=%22nur%20Ideen%20geben%22;id=uva.x002624295;view=1up;seq=301;start=1;sz=10;page=search;num=277. <br class="br">On University Studies (1803)

Source: Chasm City (2001), Chapter 12 (p. 177).

"On the Harmony of Theory and Practice in Mechanics" (Jan. 3, 1856)
Context: Another evil, and one of the worst which arises from the separation of theoretical and practical knowledge, is the fact that a large number of persons, possessed of an inventive turn of mind and of considerable skill in the manual operations of practical mechanics, are destitute of that knowledge of scientific principles which is requisite to prevent their being misled by their own ingenuity. Such men too often spend their money, waste their lives, and it may be lose their reason in the vain pursuits of visionary inventions, of which a moderate amount of theoretical knowledge would be sufficient to demonstrate the fallacy; and for want of such knowledge, many a man who might have been a useful and happy member of society, becomes a being than whom it would be hard to find anything more miserable.
The number of those unhappy persons — to judge from the patent-lists, and from some of the mechanical journals — must be much greater than is generally believed.<!--p. 176

Source: Investigations into the Method of the Social Sciences, 1883, p. 58