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What the World is Like

The most straightforward philosophical way of thinking about the world's interaction with a baby or other person is in terms of its input-output relations with its environment. Unfortunately for our philosophical convenience, but fortunately for our survival, this is not the way the world is structured.

The world's structure is not directly describable in terms of the input-output relations of a person. The basic structure of the world involves the interaction of elementary particles on time scales of seconds, but intelligence did not evolve in structures of small numbers (mere billions) of elementary particles. When intelligence evolved, it was in structures of the order of elementary particles and time scales of the order of seconds to years and very complex hierarchical structures. Even then only some of the higher level and slower objects and events are directly perceivable. Even bacteria, weighing one picogram grams, have about atoms. The mass of a small virus is about 10 attograms [attogram = grams].

Even on the human size and time scale, the world is not structured in terms of human input-output relations. Moreover, much of the determinism of the world at the microscopic level appears as non-deterministic at the level at which a person can interact with the world. 6

Animal behavior, including human intelligence, evolved to survive and succeed in this complex, partially observable and very slightly controllable world. The main features of this world have existed for several billion years and should not have to be learned anew by each person or animal. In order to understand how a well-designed baby should work, we need to understand what the world is like at the gross level of human interaction with the environment.

Here are some of the world's characteristics. A baby innately equipped to deal with them will outperform a Lockean baby.

appearance and reality
Some properties of the world are stable even though their appearances change. Objects last from seconds to centuries, while appearances change in fractions of a second. Therefore, humans, animals and robots are better off representing information about objects in so far as it can be obtained by observation and inferred from past experience or is innate.7 [McC99] presents a puzzle in which the subject must experiment to determine the 3-d reality behind the 2-d appearances.

things of interest
Some aspects of the world are relevant to an animal's or person's survival or prosperity, and others are not. However, notice that human and animal curiosity concerns many aspects of the world not related to survival or enjoyment. Other details of shape and pattern are not interesting.

semi-permanent objects
Much of the world consists of three-dimensional objects that have masses, moments, compliances, hardnesses, chemical composition, shapes, outer surfaces with textures and colors, are often made of identifiable parts and which move relative to the rest of the object. A particular object can disappear from perception and reappear again. The location of an object in the world is more persistent than its location in the visual field.

Objects usually have internal structures that are not apparent to human senses.

A baby seems to have an innate interest in the names of things quite apart from what may be immediately useful. Thinking of it linguistically, it is an interest in semantics, not just in syntax. We'd better build that into our robotic children.

continuity of motion
Objects move continuously passing through intermediate points and intermediate orientations.

continuous processes
Besides moving objects, there are many continuous processes with intermediate states.

two dimensional world
Because of gravity, much of the world is two dimensional with its simpler topology. Paths can block other paths.

specific objects
The environmment of a child contains other people, usually including a mother, and parts of people including parts of the child itself. Objects often have parts which are objects. However, often only some of the parts are separately identifiable. The boundaries of the parts are often not definite.

Objects that are solid do not ordinarily penetrate one another. Some are rigid and some are flexible.

Objects require supporting surfaces, and an unsupported object falls to a lower surface.

kinds of objects
Objects have kinds, and objects of the same kind have properties associated with the kind.8 Babies are ready very early to learn what kinds there are.

Objects not only have individual properties and belong to kinds, but different objects and kinds have relations with one another. At least some ternary relations such as betweenness are basic. Also ``A is to B as C is to D'' seems to be basic. In its numerical use, it reduces to the equality of two fractions, but the quaternary relation seems to be basic in common sense usage.

In philosophy, AI, and computer science, there is an overemphasis on unary relations, i.e. properties.

natural kinds
Many of the objects a child encounters, e.g. lemons, belong to natural kinds. The objects of a natural kind have yet undiscovered properties in common. Therefore, a natural kind is not usually definable by an if-and-only-if sentence formulated in terms of observables.

fundamental kinds
Animate objects are to be understood in terms of their desires and actions. Inanimate objects are passive. Some objects are edible by humans and some are not. These kinds pervade the baby's environment.

Kinds belong to higher kinds and have relations. Red is a color and color is a quality. This is a fact of logic rather than about the physical world, but its usefulness is dependent on objects being naturally grouped into kinds rather than being all completely different.

sets and numbers
There are sets of objects and other entities. This includes both sets of objects perceivable on a single occasion and sets organized more abstractly. Sets can often be counted. Some are more numerous than others and this is significant. Sets can be used up, e.g. all the food can be eaten.

situations and kinds of situations
Kinds of situations recur.

the body
The baby itself and its parts are objects.

Some objects can be moved with the arms and legs of a child.

Mothers help a baby that cries.

A mother loves her baby.

unimportant aspects
Many aspects of the world are ordinarily unimportant for a human or animal. For many purposes, shadows are mere epiphenomena.

quantitative physics
Humans could act more precisely if our senses gave us numerical measures of time, distance, velocity, humidity, temperature, etc.; our minds could do rapid arithmetic with them, and we could give numerical values to the signals telling our muscles how fast to contract. Nature didn't give us this, but we can build it into our robots as an add-on to the kinds of semi-quantitative information human senses give us.

Newtonian physics
While the world is not fully determinate at the level at which humans interact with it, many events are related in a simple numerical way. For example, describes the distance a body will fall, and hot bodies cool at a rate proportional to the difference in temperature between a body and its surroundings.

The material world is built up from atoms and molecules. It is more fundamental than most of the above facts but is similar to them. While even ancient Greek philosophers like Democritus could conjecture that the world was built from atoms, John Dalton was the first person to offer scientific evidence for the fact.

Very complex structures, (e.g. groups, rings and fields), exist in a mathematical sense.

mathematics of the world
Very complex mathematics is ``unreasonably effective'' in understanding and controlling the physical world.

All the above are facts about the world. All but the last few may or may not be represented innately. We can also imagine that we might have evolved innate knowledge of the above mathematically expressible facts, but alas we didn't. The items listed are certainly not a complete set of facts about the commonsense world that a well-designed child might know about. Moreover, innate mechanisms for dealing with phenomena related to these facts do not always take a form describable as having certain knowledge.

In the next section we consider which of the above facts a child might know about or have special mechanisms for dealing with.

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John McCarthy