Another SFI seminar I wish I could have attended: Virtual Stability: A General Characteristic of Complex Adaptive Systems?
[...] we define the concept of virtual stability as a state in which a system employs self-monitoring and adaptive control to maintain itself in a configuration that would otherwise be unstable. The energy expended in this gains the system a major increase in its flexibility of behavioral response to environmental change. Virtual stability is proposed as a general principle of complex adaptive systems.
The speaker, Burton Voorhees, wrote a paper in 2002: Virtual Stability: A Principle of Complex Systems [PDF]. Along with that stronger in-title assertion, the introduction says:
We suggest that virtual stability provides an answer to the question of whether or not there is a direction to evolution.
A fairly bold statement. Perhaps he has endured some questioning and criticism seeing as the seminar title uses looser language and is phrased as a question. 
Curiously, “virtual stability” does not appear in Dr. Voorhees’ list of interests.
Ignoring the uncertainty of the notion, virtual stability fits well in one of my favorite complex system paradigms:
- solid ↔ liquid ↔ gas
- order ↔ chaos ↔ random
- rest ↔ inhalation/exhalation ↔ seizure
- fixed/periodic ↔ complex ↔ chaotic
- stable ↔ virtually stable ↔ unstable
- etc.
Where changes between states is like a phase-transition.
As far as I know this paradigm is in no way “official”, but I find it a meaningful guide. The idea was first presented to me in Christopher Langton‘s thesis. If you are into complex systems, you should not hesitate to find a copy. Not only is it a wonderful story of discovery, it’s rife with humor! An inspiring work.
As for Dr. Voorhees’ ideas, I’d like to know more. It would be wonderful if SFI would publish audio and/or video of their seminars.