What is the relationship between reductionism and complexity?

[Ratzinger]

I'm looking for some good definitions/ explanations of the two words reductionism and complexity.

As I once read reductionist say emergent properties and complex behaviour are epistemological issues, necessary conceptualisations to make the world understandable. Any additional non-physical substances and rules that can't be derived from physics are denied. I think all scientists agree more or less on that kind of reducionism/ physicalism.

But I heard there are varying degrees of reductionist thinking. Which are they??

Also, even accepting the reductionism agenda, looking at a biological cell, a sophisticated man-made machine or human societies, you can't shake the feeling there is more to it. It seems there is sort of an own, new reality when certain (complex?) many-body systems form.

That may sound naive, which is mostly due to that I have not seen any satisfying definitions of the terms emergence and complexity yet. Does anyone of you have some good ones?

thanks

 

[CosminaPrisma]

http://www.meta-library.net/evp-mind/index-frame.html"



You might find this link helpful. She's approching the topic as a philosopher of science, not a theologian but some of the other stuff on the site by other authors might be biased. As you follow along in the lecture she will go on to explain reductive physicalism and non-reductive physicalism...in order to get what she was talking about I had to follow each part of the presentation in order.

You also might want to look at the archives of the "A Place for Conciousness" book discussion, I think there is some posts about causation there, I don't really know, but it might be help you in investigating answers to your question.

 

[Rade]

Reducibility. Suppose a system made of two parts, [P] and [Q]. If each has effect on other [P] <----> [Q] it can be said that the system is completely whole. Or if one part only effect other [P] ---> [Q], thus a partially whole system. When the system reaches a state where the whole is composed of two independent parts [P] [Q] with no interaction the system is said to be "reduced". From R. Ashby. 1956. An introduction to cybernetics.

Thus,

Complexity = Is the study of ( and reality of ) whole systems that are not reduced.

 

[selfAdjoint]

Reducibility. Suppose a system made of two parts, [P] and [Q]. If each has effect on other [P] <----> [Q] it can be said that the system is completely whole. Or if one part only effect other [P] ---> [Q], thus a partially whole system. When the system reaches a state where the whole is composed of two independent parts [P] [Q] with no interaction the system is said to be "reduced". From R. Ashby. 1956. An introduction to cybernetics.

Thus,

Complexity = Is the study of ( and reality of ) whole systems that are not reduced.

Good to see Ashby quoted. The British school of cybernetics is too much ignored, in my opinion. I would modify your definition to say that complexity is the study of (what we might call) Ashby-whole systems that never become reduced. Or at least not in the short term during which we observe them (cf. ergodicity).

 

[NickJ]

For philosophical points of view, see:

http://plato.stanford.edu/entries/properties-emergent/

which is an article on "emergence". Also see

http://plato.stanford.edu/entries/physics-interrelate/

which is an article on various kinds of inter-theoretic relations (including reduction).

Finally, for an article on whether everything is "just physical", see

http://plato.stanford.edu/entries/physicalism/