Robert Rosen

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Robert Rosen (June 27, 1934 – December 28, 1998) was an American theoretical biologist and Professor of Biophysics at Dalhousie University.


  • The physical structures of organisms play only a minor and secondary role... The only requirement which physical structure must fulfill is that it allow the characteristic behaviors themselves to be manifested. Indeed, if this were not so, it would be impossible to understand how a class of systems as utterly diverse in physical structure as that which comprises biological organisms could be recognised as a unity at all.
  • I do not consider myself a philosopher. I am a biologist, attempting to grapple with the Schrodinger question, “What is Life?” It turns out that this is not an empirical question, to be resolved through observation in a laboratory.
  • On balance, the cartesian metaphor of organism as machine has proved to be a good idea. Ideas do not have to be correct in order to be good; its only necessary that, if they do fail, they do so in an interesting way.
    • R. Rosen Life, p. 248, quoted in: Carl F Gethmann (2011) Lebenswelt und Wissenschaft. p. 139
  • Perhaps the first lesson to be learned from biology is that there are lessons to be learned from biology.
    • Robert Rosen (2013), Essays on Life Itself Chapter 18

Fundamentals of measurement and representation of natural systems. (1978)


Rosen, Robert. Fundamentals of measurement and representation of natural systems. New York: North-Holland, 1978.

  • The point of departure is the measurement problem, as it appears in physics; the manner in which measurements allow us to characterize subsystems; the role of such subsystems as tools in system analysis; and the relationships existing between different ways of perceiving or interacting with the same system. Our conclusions are: (1) there exists no universal family of of analytic units appropriate for the treatment of all interactions; (2) there are on the contrary many such families of analytic units, all of which are equally “real” and entitled to be treated on the same footing; (3) the appropriate use of natural interactions can enormously extend the class of physical observables accessible to us; (4) the concept of a model must be formulated, in its most general terms, as the sharing of a subsystem by two otherwise distinct systems, capable of imposing the same dynamic on an appropriate system with which they can both interact. We establish these results through a variety of terminologies which turn out to be equivalent: stability, invariance, symmetry, homeostasis.
  • It is essential to realize at this point that the formalism to be developed, although we cast it initially primarily in the framework of natural systems, is in fact applicable to any situation in which a class of objects is associated with real numbers, or in fact classified or indexed by any set whatever. It is thus applicable to any situation in which classification, or recognition, or discrimination is involved; indeed, one of the aims of our formalism is to point up the essential equivalence of the measurement problem in physics with all types of recognition or classification mechanisms based on observable properties of the objects being recognized or classified.

"Some comments on systems and system theory," (1986)


Robert Rosen, "Some comments on systems and system theory." in: International Journal of General Systems. Vol 13, (1986);

  • For a long time, people have been trying to characterize or define the notion of system. After all, “systems” are supposed to be what System Theory is about. The results so far have been contradictory and unsatisfactory. This confusion at the foundations has led many to conclude that there is no such thing as a "system" and hence to deny that System Theory is about anything. Even those most sympathetic to the notion have difficulties at this level. The very founders of System Theory did not try to say what a system was; and as for System Theory, they characterized it only obliquely, by saying it comprised all studies of interest to more than one discipline. They thereby begged the entire question.
    • p. 1
  • Let us begin by observing that the word "system" is almost never used by itself; it is generally accompanied by an adjective or other modifier: physical system; biological system; social system; economic system; axiom system; religious system; and even "general" system. This usage suggests that, when confronted by a system of any kind, certain of its properties are to be subsumed under the adjective, and other properties are subsumed under the "system," while still others may depend essentially on both. The adjective describes what is special or particular; i.e., it refers to the specific "thinghood" of the system; the "system" describes those properties which are independent of this specific "thinghood."
This observation immediately suggests a close parallel between the concept of a system and the development of the mathematical concept of a set. Given any specific aggregate of things; e.g., five oranges, three sticks, five fingers, there are some properties of the aggregate which depend on the specific nature of the things of which the aggregate is composed. There are others which are totally independent of this and depend only on the "set-ness" of the aggregate. The most prominent of these is what we can call the cardinality of the aggregate...
It should now be clear that system hood is related to thinghood in much the same way as set-ness is related to thinghood. Likewise, what we generally call system properties are related to systemhood in the same way as cardinality is related to set-ness. But systemhood is different from both set-ness and from thinghood; it is an independent category.
  • p. 1-2 as quoted in George Klir (2001) Facets of Systems Science, p. 4
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