Emergence is the central idea that can explain a wide variety of complex phenomena that resist analysis through reductive reasoning, such as intelligence, consciousness, and free will.
Intelligence is a property that emerges from a sufficiently large, interconnected, hierarchical system that specializes in pattern recognition and prediction. The emergent property we call intelligence is characterized by the ability to simultaneously identify patterns and predict upcoming sequences at widely divergent levels of complexity, from the simplest patterns of raw sensory data up to the most complex meta-patterns imaginable. The degree of intelligence of a system is generally measured by the level of complexity at which it can identify patterns and make well-tested predictions. A common, though not required, characteristic of intelligent systems is the ability to interact with the outside system and effectuate changes that give predictable results. This allows for much more effective testing, disambiguation, and refinement of pattern identifications, and is directly analogous to the difference between the ability to perform controlled experiments vs. having to rely on natural experiments. However, just as macroeconomics and astronomy are still sciences, despite their inability to perform many controlled experiments, so an intelligent system is enhanced by, but does not require, the ability to effectuate behavior in order to be characterized as intelligent.
An intelligent system must receive inputs (sensory input) from an outside system (such as the real world) that exhibits structure and some degree of predictable patternicity in both the sequence of inputs (temporality) and across sensory modalities. Each component of the system (a cortical column, in the case of the mammalian brain) must be able to process the pattern of inputs (either from the senses, or more commonly, from lower and higher level components), identify the most likely pattern represented by the current sequence of inputs, predict the upcoming sequence of inputs, and communicate this prediction, both downward to the lower-level component producing the sequence, as well as upward to higher-level components. Each component must use higher-level components’ predictions as input to help resolve ambiguities in characterizing the pattern represented by noisy input from lower levels. Each component should treat successful predictions as confirmation of the current sequence-to-pattern mapping, but should treat falsified predictions as grounds to attempt to find a new pattern that fits the current input sequence. Any changes in the currently identified pattern should be communicated to all higher-level components, so they can treat the change as a prediction failure as well.
See also On Intelligence, by Jeff Hawkins
Consciousness is a property associated with, but not identical to, intelligence. It is characterized by (and commonly defined as) self-awareness. In terms that don’t involve circular definition, this means that a conscious system must be able to use as input its own internal states, and must be able to exhibit intelligent behavior (pattern-recognition and prediction, see above) with regards to that data, just as with external input. Because the inputs (internal states) are directly affected by the process of analyzing those states, conscious entities have, by definition, a degree of behavioral control over their inputs. Whether and how this control is exercised is dependent on the level of free will (see below) of the system. However, a system need not exhibit free will to exhibit a significant degree of consciousness: even a completely pre-programmed system, equipped with a proper feedback/regulatory system based on internal states, would be considered conscious to a very rudimentary degree.
As with intelligence, consciousness is not a binary attribute, but should be measured in degrees. It also does not require a human level of intelligence: an animal should be considered to have a level of experiential consciousness, to the extent it can (presumably) identify the pattern of internal states as what we would call a “feeling”. Many such animals also exhibit a degree of self-consciousness, as demonstrated by their ability to recognize themselves in a mirror. Social animals (primates and cetaceans, for example) also exhibit social consciousness, in that they can use their own instinctual behavior (such as arousal states, the facial flush of embarrassment, etc.) as an input toward intelligent understanding of the social situation. And, of course, human-level consciousness is characteristically associated with an ability to combine the awareness of internal states with rational deductive and inductive reasoning, and separately with the ability to use language to further refine the ability to understand, explain, and thereby predict one’s own behavior.
As with intelligence, consciousness is a property that emerges gradually with the increasing complexity of a properly organized system. It is likely that many of the same organizational principles that contribute to intelligence are also responsible for the emergence of consciousness. However, consciousness remains a more difficult property to study.
An intelligent system, particularly one with self-consciousness, needs to be goal-directed to function effectively. As mentioned before, free will is not a necessary attribute of intelligent and/or conscious systems: such a system can be pre-programmed, through evolved instinct or programmatic design, with certain goals, homeostatic ranges, internally reinforced behaviors or outcomes, etc. To the degree a system is solely controlled by such genetically-determined attributes, and/or by its immediate external environment, it does not exhibit free will. However, if the system is sufficiently intelligent and self-conscious, it becomes possible for the system to examine and change its own goals. This process is very familiar to us as humans: many of the most important parts of our lives are the times when we are attempting to determine what we want for ourselves.
As with intelligence and self-consciousness, free will is an emergent property, in that it does not arise from any single source. Rather, it is the product of a large number of complex interactions between innate drives and predispositions, values and goals imparted externally from sources we are emotionally attached to, and the complex interplay of personal experience and the processes of consciousness.
While the sources of free will are most easily expressed in human terms, it is not a uniquely human trait. As with intelligence and consciousness, humans exhibit free will to a greater degree than any other observed system. However, animals also exhibit free will to some degree, and there is no reason to think that an artificial system, if it is complex enough to exhibit sufficient intelligence and self-consciousness, and if it is given the freedom to modify itself, would not also exhibit free will.