In the Babylon 5 episode A Voice in the Wilderness, there is a reference to the third principle of sentient life.
How many principles are there, what are they, and are they unique to the Babylon 5 universe or are they taken from prior art?
Besides "capacity for self-sacrifice" and the possibility of "enlightened self-interest" mentioned in the other answers, I've run across another one in the Lurker's Guide to Babylon 5, episode 3x13, A Late Delivery from Avalon, under the "jms speaks" section:
- The ability to forgive is certainly one of the foremost principles of sentient life, even Draal would agree with that.
I don't think the show ever stated the first two, however G'Kar did make a statement in Season 1 episode 11 (Survivors):
"The Universe is run by the complex interweaving of three elements: energy, matter, and enlightened self-interest."
The self-interest part would make sense and the contradiction with the 'capacity for self-sacrifice' would add symmetry.
There are at least 3 according to the First season B5 episode "Voice in the Wilderness Part 1" the 3rd principle is the capacity for self sacrifice: the conscious ability to override evolution and self-preservation for a cause, a friend or a loved one.
JMS may have conceived the principles of sentience based on philosophical derivatives of such.
Sentience can be defined as the ability to feel, perceive and experience subjectively. As such there are 3 critical principles of sentience:
Self awareness - often referred to as self interest because actions result from stimuli relative ones perception of "self." To fully experience sentience, one must be aware of self and where one is situated relative to those things which provoke feelings and perceptions as well as experiences initiated in the subjective rather than objective interest of the self.
Intuition - the combination of intelligence, creativity and self awareness results in intuitive thought. A sentient being can use intuitive thought to imagine multiple subjective perceptions of outcome to varying circumstances that may include perceived or speculative stimuli. Conscious action and experience can result and from a defined choice based solely on the subjective intuitive thoughts. Sentient beings can deliberate using this intuitive process.
Intentionality - through the uses of intuitive though & application of self awareness the sentient being can act and thusly experience with forethought. This also allows a sentient being to act deliberately and if necessary in direct opposition to programmed physical and autonomic functions. This can facilitate such actions as self sacrifice: over riding evolution and self preservation in favor of a perceived cause, emotional attachment or moral principle.
The Third Principle of Sentient life is the capacity for self-sacrifice, the conscious ability to override evolution and self-preservation for a cause, a friend, a loved one.
That is the only one I've ever heard.