Introduction: What is AI?

rational agent

A rational agent is one that acts so as to achieve the best outcome or, when there is uncertainty, the best expected outcome.

agent

An agent is just something that acts (agent comes from the Latin agere, to do).

Acting rationally: The rational agent approach

An agent is just something that acts (agent comes from the Latin agere, to do). But computer agents are expected to have other attributes that distinguish them from mere "programs," such as operating under autonomous control, perceiving their environment, persisting over a prolonged time period, adapting to change, and being capable of taking on another's goals. A rational agent is one that acts so as to achieve the best outcome or, when there is uncertainty, the best expected outcome.

Thinking humanly: The cognitive modeling approach

If we are going to say that a given program thinks like a human, we must have some way of determining how humans think. We need to get inside the actual workings of human minds. There are two ways to do this: through introspectior-trying to catch our own thoughts as they go by-and through psychological experiments. Once we have a sufficiently precise theory of the mind, it becomes possible to express the theory as a computer program. If the program's input/output and timing behaviors match corresponding human behaviors, that is evidence that some of the program's mechanisms could also be operating in humans.

Relationship between "laws of thought" approach and thinking rationally

In the "laws of thought" approach to AI, the emphasis was on correct inferences. Making correct inferences is sometimes part of being a rational agent, because one way to act rationally is to reason logically to the conclusion that a given action will achieve one's goals and then to act on that conclusion. On the other hand, correct inference is not all of rationality, because there are often situations where there is no provably correct thing to do, yet something must still be done. There are also ways of acting rationally that cannot be said to involve inference.

Thinking rationally: The "laws of thought" approach

Logicians in the 19th century developed a precise notation for statements about all kinds of things in the world and about the relations among them. (Contrast this with ordinary arithmetic notation, which provides mainly for equality and inequality statements about numbers.) By 1965, programs existed that could, in principle, solve any solvable problem described in logical notation.~ The so-called logicist tradition within artificial intelligence hopes to build on such programs to create intelligent systems.

What is AI?

Systems that think like humans, systems that think rationally, systems that act like humans, systems that act rationally

Acting humanly: The Turing Test Approach

The Turing Test, proposed by Alan Turing (195O), was designed to provide a satisfactory operational definition of intelligence. Rather than proposing a long and perhaps controversial list of qualifications required for intelligence, he suggested a test based on indistinguishability from undeniably intelligent entities-human beings. The computer passes the test if a human interrogator, after posing some written questions, cannot tell whether the written responses come from a person or not. ~ natural language processing to enable it to communicate successfully in English. ~ knowledge representation to store what it knows or hears; ~ automated reasoning to use the stored information to answer questions and to draw new conclusions; ~ machine learning to adapt to new circumstances and to detect and extrapolate patterns.

What does the field of AI attempt to do?

The field of artificial intelligence, or AI, attempts not just to understand but also to build intelligent entities. A1 systematizes and automates intellectual tasks and is therefore potentially relevant to any sphere of human intellectual activity. In this sense, it is truly a universal field.

cognitive science

The interdisciplinary field of cognitive science brings together computer models from AI and experimental techniques from psychology to try to construct precise and testable theories of the workings of the human mind.

Obstacles to logicist approach

There are two main obstacles to this approach. First, it is not easy to take informal knowledge and state it in the formal terms required by logical notation, particularly when the knowledge is less than 100% certain. Second, there is a big difference between being able to solve a problem "in principle" and doing so in practice. Even problems with just a few dozen facts can exhaust the computational resources of any computer unless it has some guidance as to which reasoning steps to try first.

The Total Turing Test

Turing's test deliberately avoided direct physical interaction between the interrogator and the computer, because physical simulation of a person is unnecessary for intelligence. However, the so-called total Turing Test includes a video signal so that the interrogator can test the subject's perceptual abilities, as well as the opportunity for the interrogator to pass physical objects "through the hatch." To pass the total Turing Test, the computer will need ~ computer vision to perceive objects, and ~ robotics to manipulate objects and move about.