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“人工智能威胁人类论” (2)   合理地定义“人工智能”

程京德

为了把问题讨论清楚，我们当然首先需要定义清楚问题的核心：“人工智能(Artificial Intelligence, AI)”。在历史上，“人工智能”一词首先由当时一位年轻的计算机科学家、美国Dartmouth学院数学助理教授、日后的图灵奖获得者麦卡锡(John McCarthy, 1927-2011) 于1955年用在他有关召开首个人工智能国际会议(The Dartmouth Summer Research Project on Artificial Intelligence, 1956, 现在一般被称为Dartmouth会议)的提案书当中，现在世界上一般认为该会议是开辟了人工智能这个研究领域的历史性事件 [1]。提案书的引言部分中首次使用了“artificial intelligence”一词：“We propose that a 2 month, 10 man study of artificial intelligence be carried out during the summer of 1956 at Dartmouth College in Hanover, New Hampshire. The study is to proceed on the basis of the conjecture that every aspect of learning or any other feature of intelligence can in principle be so precisely described that a machine can be made to simulate it. An attempt will be made to find how to make machines use language, form abstractions and concepts, solve kinds of problems now reserved for humans, and improve themselves. We think that a significant advance can be made in one or more of these problems if a carefully selected group of scientists work on it together for a summer.”[1] 提案书接下来还列举了人工智能问题的一些侧面(some aspects)如下：Automatic Computers, How Can a Computer be Programmed to Use a Language, Neuron Nets, Theory of the Size of a Calculation, Self-lmprovement, Abstractions, Randomness and Creativity [1].

1955年当时，麦卡锡并没有把“人工智能(artificial intelligence)”清晰地作为一个概念定义明确之后才使用这个名词，而是直接用在了Dartmouth会议提案书中（尽管我们可以从Dartmouth会议提案书的前言部分可以大致体会出提案者们的大概意图）。这是“人工智能”后来在概念上、领域范围上一直处于混乱不清状况的最主要原因。显然，麦卡锡等人在1955年的Dartmouth会议提案书中明确列举的几个方面中有些早已成为计算机科学中相对独立的领域而现今不再被包括在人工智能领域之中了，而现在却有许多其它没有被列举到的许多方面却被冠以“人工智能”的名义。

笔者认为，对于任何一个概念，如果它不是在社会上自然形成而是由其第一位提案者提出的，那么，尊重该提案者之初始定义中最基本的内容是必要的。后人可以对该原始定义进行修改和补充说明，但是这种修改和说明应该不对它的内涵和外延有本质上的改动才是合适的。但是，“人工智能”这个概念的内涵和外延基本上可以说是没有提案者之初始清晰定义，而是在社会上逐渐自然形成的。于是，至今没有清晰定义的结果就造成了今天这个从知名科学家到小报记者都在基于自己对“人工智能”的个人理解来各说各话的局面。

麦卡锡在其2007年最后修订过的问答录中给出了他本人对“人工智能(artificial intelligence)”、“智能(intelligence)”、“人类智能(human intelligence)”、“计算机智能(computer intelligence)”的定义如下[2]：

Q. What is artificial intelligence?

A. It is the science and engineering of making intelligent machines, especially intelligent computer programs. It is related to the similar task of using computers to understand human intelligence, but AI does not have to confine itself to methods that are biologically observable.

Q. Yes, but what is intelligence?

A. Intelligence is the computational part of the ability to achieve goals in the world. Varying kinds and degrees of intelligence occur in people, many animals and some machines.

Q. Isn't there a solid definition of intelligence that doesn't depend on relating it to human intelligence?

A. Not yet. The problem is that we cannot yet characterize in general what kinds of computational procedures we want to call intelligent. We understand some of the mechanisms of intelligence and not others.

Q. Is intelligence a single thing so that one can ask a yes or no question “Is this machine intelligent or not?”?

A. No. Intelligence involves mechanisms, and AI research has discovered how to make computers carry out some of them and not others. If doing a task requires only mechanisms that are well understood today, computer programs can give very impressive performances on these tasks. Such programs should be considered “somewhat intelligent”.

Q. Isn't AI about simulating human intelligence?

A. Sometimes but not always or even usually. On the one hand, we can learn something about how to make machines solve problems by observing other people or just by observing our own methods. On the other hand, most work in AI involves studying the problems the world presents to intelligence rather than studying people or animals. AI researchers are free to use methods that are not observed in people or that involve much more computing than people can do.

Q. What about other comparisons between human and computer intelligence?

Arthur R. Jensen [Jen98], a leading researcher in human intelligence, suggests “as a heuristic hypothesis” that all normal humans have the same intellectual mechanisms and that differences in intelligence are related to “quantitative biochemical and physiological conditions”. I see them as speed, short term memory, and the ability to form accurate and retrievable long term memories.

Whether or not Jensen is right about human intelligence, the situation in AI today is the reverse.

Computer programs have plenty of speed and memory but their abilities correspond to the intellectual mechanisms that program designers understand well enough to put in programs. Some abilities that children normally don't develop till they are teenagers may be in, and some abilities possessed by two year olds are still out. The matter is further complicated by the fact that the cognitive sciences still have not succeeded in determining exactly what the human abilities are. Very likely the organization of the intellectual mechanisms for AI can usefully be different from that in people.

Whenever people do better than computers on some task or computers use a lot of computation to do as well as people, this demonstrates that the program designers lack understanding of the intellectual mechanisms required to do the task efficiently.

Q. Does AI aim to put the human mind into the computer?

A. Some researchers say they have that objective, but maybe they are using the phrase metaphorically. The human mind has a lot of peculiarities, and I'm not sure anyone is serious about imitating all of them.

Q. Does AI aim at human-level intelligence?

A. Yes. The ultimate effort is to make computer programs that can solve problems and achieve goals in the world as well as humans. However, many people involved in particular research areas are much less ambitious.

Q. How far is AI from reaching human-level intelligence? When will it happen?

A. A few people think that human-level intelligence can be achieved by writing large numbers of programs of the kind people are now writing and assembling vast knowledge bases of facts in the languages now used for expressing knowledge.

However, most AI researchers believe that new fundamental ideas are required, and therefore it cannot be predicted when human-level intelligence will be achieved.

Q. Are computers the right kind of machine to be made intelligent?

A. Computers can be programmed to simulate any kind of machine.

Many researchers invented non-computer machines, hoping that they would be intelligent in different ways than the computer programs could be. However, they usually simulate their invented machines on a computer and come to doubt that the new machine is worth building. Because many billions of dollars that have been spent in making computers faster and faster, another kind of machine would have to be very fast to perform better than a program on a computer simulating the machine.

目前最新版的牛津计算辞典把“artificial intelligence”定义为：“A discipline concerned with the building of computer program that perform tasks requiring intelligence when done by humans. However, intelligent tasks for which a decision procedure is known (e.g. inverting matrices) are generally excluded, whereas perceptual tasks that might seem not to involve intelligence (e.g. seeing) are generally included. For this reason, AI is better defined by indicating its range. Examples of tasks tackled within AI are: game playing, automated reasoning, machine learning, natural-language understanding, planning, speech understanding, and theorem proving.”[3]

在这里，笔者试图根据Dartmouth会议提案书、麦卡锡本人问答录、牛津计算辞典的相关内容，对应该如何合理地定义“人工智能”归纳几点建议。

首先，从历史观点来看，“人工智能”是从计算机科学领域派生出来的，其所谓“人工”应该是指使用“计算机”这个工具，无论是把目前可用的“计算机”用于研究和开发，还是创造出将来的“具有智能的计算机”。

其次，从上面第一点，立刻就可以归纳出第二点：“人工智能”的研究、创造、开发、维护、应用的主要手段应该是“计算”，尽管可以不排除使用其它手段作为辅助实验手段。

再次，“人工智能”的最终目的，试图实现（模拟）的应该是“人类智能”，尽管可以不排除实现（模拟）“动物智能”作为辅助实验手段。

最后，“人工智能”的各种具体应用，应该是完全自动化的，亦即，是由计算程序来完全控制、实施、完成在现实世界中需要人类智能的那些工作。

综上所述，笔者认为，“人工智能”可以被定义为：“作为一个学科，人工智能研究那些以计算机为工具，以计算为手段，开发出具备了类似人类智能之问题解决能力的计算程序来控制计算机实施并完成通常需要人类智能的工作任务之原理、方法和技术”。

最后，蛇足一句。Dartmouth会议的提案者中，有世界知名的信息论创立者香农(C.E. Shannon, 1916-2001)、和麦卡锡、明斯基(M.L. Minsky, 1927-)两位日后的图灵奖获得者;在Dartmouth会议参加者当中还有日后的图灵奖和诺贝尔奖获得者西蒙(H.A. Simon, 1916-2001)、图灵奖获得者纽厄尔(A. Newell, 1927-1992)，此会议的参加者水平之高，其开拓力之深远、其影响力之广泛，在计算机科学发展史上大概是无可与其比肩的。

参考文献

[1] J. McCarthy, M.L. Minsky, N. Rochester, and C.E. Shannon, “A Proposal for the Dartmouth Summer Research Project on Artificial Intelligence,” Aug. 31, 1955.

[2] J. McCarthy, “WHAT IS ARTIFICIAL INTELLIGENCE?”, Revised Nov. 12, 2007.

[3] A Dictionary of Computing, 6th Edition, Oxford University Press, 2008.