From a salmon swimming upriver to breed, to a tree spreading its roots, or a cell migrating to a more suitable environment, known life can move in ways that are meaningful to its existence. Where rocks don’t go out of their way to avoid erosion or a river doesn’t intentionally move to warmer climates to avoid being frozen, living organisms strive to remain as such, and these observable reactions help to create a broad description of life.
Unlike many others, this definition does not require evolution, reproduction, or a basis of organic chemistry, or complex systems; as long as the desire to remain alive is observable, the trait of ‘living’ should be applied. In such a broad scope, there may fall some false positives, though. Computer programs for example, can be designed to emulate known life: a model deer will run at the sound of gunfire, or a digital merchant will seek revenge on digital people who stole their digital goods. What makes these not living, especially when they mimic what is obviously alive? While life that might be found on other planets in unlikely to be digital, the possibility of atypical forms of life must be considered.
Or what if, on a utopian planet, the necessity for the ‘fight or flight’ nature of life on Earth is non-existent, and instead life is at a hibernation-like state? While beings on such a world may be capable of defending themselves or moving out from an equilibrium state, without intervention they might never express the characteristics required in this definition of life. Without direct observation, what is actually alive might be overlooked as otherwise, but would that intervention destroy their ecosystem? Like with the spread of disease European travelers brought to North America, which contributed to the deaths of over 15 million people, interference has often been historically catastrophic.
Testing for this trait would require much forethought on the part of scientists regarding morals. Does torturing a candidate to see its reactions seem reasonable for progress? The less ‘evil’ choice of observing the candidate in its own environment also has repercussions. Do scientists, through inaction, let harm come to what might be life? What if it feels pain, or grief, or some negative emotion due to human intervention? Still, risks must be taken for better or for worse, and if as much thought is put into preserving extraterrestrial life as is put into finding it, the risks to ourselves should be no greater than that of our undiscovered neighbors, which is as good as one might hope for.
The idea that life is something in a constant state of attempting to remain alive is incredibly interesting! It is broad yet applies to what we generally perceive as living things. I love the simplicity of the definition and I think that if life is ever defined, it will be a simple definition as yours.
I am quick to question the definition because I believe that it includes things that I would not hold to be life. A fire, for instance, I could argue is life by this definition, because it shrinks away from water but will move towards areas that have more fuel for it to consume, thus reacting to stimuli to remain in its constant state. This may be alright though- for some might define fire as a form of life.