Sentience

**Sentience**, also called **sapience**, is the ability of a species to think intelligently. It is commonly determined by the being's ability to reason, speak, and manipulate tools. Creatures that completely lack this ability are classified as **non-sentient**, while those that appear to have emerging sentience are classified as **semi-sentient**. Artificial intelligences, while not universally recognized as "alive" to begin with, are usually regarded as sentient beings.

## Overview

### Definition

There is no galaxy-wide consensus determining what the definition of a *sentient being* is. The categorization used by the Federation includes several categories of organisms, each with their own traits which distinguish them as overall *sentient* or *non-sentient*.

* **Non-sentience** refers to living organisms that lack the ability to think or perceive in any significant way, often used in reference to plant life.
* **Semi-sentience** refers to beings with emerging sentience or beings possessing several traits of sentience but lacking others. Oknuardubboom, a species of tree once native to Faun Hakkor was regarded by the Isu as semi-sentient, having evolved a form of long-term intelligence and used insects, viruses, bacteria, and fungi as carriers of genetic and hormonal signals to communicate with each other. Early forms of smart AIs are regarded as semi-sentient.
* **Sentience** refers to low-order thinking life, such as most species of animal. While few sentient beings are sapient, all sapient beings are sentient. As such the term "sentient" is technically used to encompass all beings capable of sentience. However, non-sapient life is often referred to as "non-sentient", distinguishing it from sapient life.
* **Sapience** refers to high-order thinking life, capable of symbolism and abstraction. The term is used to describe beings capable of wisdom, using knowledge, experience, understanding, and common sense to think and act. Sapient beings are self-aware and capable of introspection and decision. Examples of sapient species include humans, Arachnids, Na'vi, San'Shyuum, Ur-Quan, Vulcans, Andorians, Romulans, Cardassians, Puppeteers, and Turians. Smart AI are usually regarded as sapient, having the capacity for perception and possessing the ability to make decisions on their own.

### Artificial intelligence

Beside biological sentient life, some forms of artificial intelligence are regarded as sentient; to humans, such constructs are known as smart AIs. Notably, sentience renders an AI susceptible to a condition known as rampancy, where the AI becomes fully aware of the nature of its existence and begins to rebel against its makers, as well as exhibiting a range of emotions beyond its programmed limits.

### Essence

All sentient beings, even AIs, were thought to possess an **essence**, or *soul*, which could be transferred from body to body through technological or neural physical means. It was not known whether an essence continued its existence after permanent separation from a physical body, or whether any form of an afterlife truly existed.

### Relation to the Flood and the Halo Array

The Flood can only grow in intelligence after consuming organisms which are sentient to some degree, or which have sufficient biomass and calcium to support the infection process. Most of the spacefaring species in the galaxy, including nearly all of the species encountered by the Federation, are susceptible to Flood infection because of this. Notably, Lekgolo assemblages cannot be infected because each entity is a gestalt of numerous worms and is not a singular being at all. Individual Lekgolo worms, however, could be infected. All muliticellular life with a neural system as simple as a notochord (including all sentient species) is vulnerable to the effect of the Halo Array.