Intelligence has various definitions, and it can be implemented in different areas of life. However, we will focus on intelligence as the ability to do the right thing at the right time where doing nothing would be worse. Natural or artificial, intelligence and cognitive ability is associated with humanity, with our ability to rationalize.
It requires the ability to perceive contexts of action, the ability to act and to associate certain contexts with certain actions. Sure, plants are smart like a thermostat. Both can associate changes in the direction of light and changes in temperature respectively, and act on these changes.
We find here the distinction between intelligence and cognitive ability. A system is considered cognitive if it can modify its intelligence, which plants and thermostats are unable to do. Cognitive systems can learn new contexts and actions and / or associations between them.
Now that we have defined intelligence, we can move on and conceptualize artificial intelligence in the next article.