Here's why:
* Viability refers to the capability of surviving and developing. It implies the potential for growth and continued existence.
* Life itself is a noun, not a descriptor of the ability to live.
* Survival implies overcoming challenges, while viability focuses on the inherent potential to live.
Other words that could be used in certain contexts:
* Life force: This refers to the vital energy or principle that animates living organisms.
* Vitality: This refers to the state of being strong and active, which is often associated with life.
* Survivability: This emphasizes the capacity to withstand threats and challenges.
The best word will depend on the specific context and the nuance you wish to convey.