Intelligence is the capacity to acquire and apply knowledge. Knowledge is acquired when it is represented in a system. Action is the application of knowledge. Thus, all systems in which actions occur are intelligent.
The potential for intelligent behavior is determined by the existence of a goal, the opportunities to acquire and apply knowledge that are relevant to the goal, the resources available to acquire and apply knowledge, and the capacity of the knowledge representation to express truths. With the exception of the goal, adjusting these constraints scales intelligence.
Intelligence requires a goal to determine action selection. No actions occur in systems without goals, and therefore such systems are not intelligent. The goal of a system does not influence the scale of intelligence of the system (which can be thought of as the magnitude of a vector), but only its purpose (which can be thought of as the direction of the same vector).
Opportunities to acquire knowledge range from stones falling on levers (the force exerted on the lever – from the perspective of the lever) to humans touching hot elements (nerve impulses from the sensory system – from the perspective of the human mind). No observation is fundamentally superior. Representations of observations (as knowledge) determine potential applications.
Opportunities to apply knowledge exist when it is possible for a system to perform an action. At the beginning of a game of chess, each player has many opportunities to apply knowledge. After the losing player has made his/her final move, the player has no further opportunities to apply his/her knowledge. Opportunities to acquire or apply knowledge which are not relevant to the goal do not influence the potential for intelligent behavior because they will not influence action and will not be applied, respectively.
Resources to acquire and apply knowledge make action possible. The resources available to apply the laws of nature are typically presumed infinite (mathematical models preserve truth and the laws of nature conserve energy, but just as mathematical models require resources for the completion of proofs, it can be assumed that the laws of nature may require resources). This differs from the limited resources available to computers and human minds.
Knowledge representations range from the experience of observations (the force exerted on the lever and the nerve impulse) to stored, abstract concepts (mathematical models written on paper and memories in a mind). All knowledge can be expressed as truths. Knowledge representations express truths with respect to the perspectives defined by their grammars. Knowledge representations with wider perspectives (fewer assumptions) are subject to fewer biases, and are therefore more expressive.
The degree to which an intelligent system observes itself determines its level of consciousness. Most humans are not capable of independently observing which of their neurons are firing at a given moment, or the location of the electrons traveling through their electronic devices. The availability of such observations would result in a higher state of consciousness. Perfect observation would allow a system to be completely aware (although attempting to observe all of a system at the same time, including its state of observing itself, is an infinite set), resulting in the highest possible state of consciousness. Intelligent systems that are conscious of their action selection are able to optimize this process, subject to the capacity of their knowledge representation to express truths.