LECTURE SIX FUNCTIONALISM 第六讲功能主义
第六讲 功能主义 LECTURE SIX FUNCTIONALISM
WHAT IS FUNCTIONALISM? that what makes something a mental state of a particular Functionalism in the philosophy of mind is the doctrine type does not depend on its internal constitution, but rather on the way it functions, or the role it plays, in the system of which it is a part Functionalism is a theoretical level between the physical is different from its predecessors of put [21 Therefore, it implementation and behavioural out Cartesian dualism (advocating independent mental and physical substances) and Skinnerian behaviourism and physicalism(declaring only physical substances) because it is only concerned organization or its software programs,, through its with the effective functions of of the brai
WHAT IS FUNCTIONALISM? Functionalism in the philosophy of mind is the doctrine that what makes something a mental state of a particular type does not depend on its internal constitution, but rather on the way it functions, or the role it plays, in the system of which it is a part。 Functionalism is a theoretical level between the physical implementation and behavioural output.[2] Therefore, it is different from its predecessors of Cartesian dualism (advocating independent mental and physical substances) and Skinnerian behaviourism and physicalism (declaring only physical substances) because it is only concerned with the effective functions of the brain, through its organization or its ‘software programs’
MACHINE-STATE FUNCTIONALISM Hilary Whitehall Putnam(born July 31, 1926) is an American philosopher, mathematician and computer scientist, who has been a central figure in analvtic philosophy since the 1960S, especially in philosophy of mind, philosophy of language, philosophy of mathematics and philosophy of science. 2 He is known for his willingness to apply an equal degree of scrutiny to his own philosophical positions as to those of others, subjecting each position to rigorous analysis until he exposes its flaws. As a result, he has acquired a for frequently changing his own position. 4 Putnam is currently Cogan University Professor Emeritus t Harvard Univer
MACHINE-STATE FUNCTIONALISM Hilary Whitehall Putnam (born July 31, 1926) is an American philosopher,mathematician and computer scientist, who has been a central figure in analytic philosophy since the 1960s, especially in philosophy of mind, philosophy of language, philosophy of mathematics, and philosophy of science. [2] He is known for his willingness to apply an equal degree of scrutiny to his own philosophical positions as to those of others, subjecting each position to rigorous analysis until he exposes its flaws.[3] As a result, he has acquired a reputation for frequently changing his own position.[4] Putnam is currently Cogan University Professor Emeritus at Harvard University
THE VERY IDEA OF MACHINE-STATE FUNCTIONALISM The early functionalist theories of Putnam(1960, 1967) can be seen as a response to the difficulties facing behaviorism as a scientific psychological theory, and as an endorsement of the(new) computational theories of mind which were becoming increasingly significant rivals to it. According to Putnams machine state functionalism any creature with a mind can be regarded as a Turing machine(an idealized finite state digital computer) whose operation can be fully specified by a set of instructions(a machine table or program) each having the form If the machine is in state S, and receives input I, it will go into state Sk and produce output O, (for a finite number of states, inputs and outputs A machine table of this sort describes the operation of a deterministic automaton, but most machine state functionalists(e. g. Putnam 1967)take the proper model for the mind to be that of a probabilistic automaton: one in which the program specifies, for each state and set of inputs, the probability with which the machine will enter some subsequent state and produce some particular output
THE VERY IDEA OF MACHINE-STATE FUNCTIONALISM The early functionalist theories of Putnam (1960, 1967) can be seen as a response to the difficulties facing behaviorism as a scientific psychological theory, and as an endorsement of the (new) computational theories of mind which were becoming increasingly significant rivals to it. According to Putnam's machine state functionalism, any creature with a mind can be regarded as a Turing machine (an idealized finite state digital computer), whose operation can be fully specified by a set of instructions (a “machine table” or program) each having the form: If the machine is in state Si , and receives input Ij , it will go into state Sk and produce output Ol (for a finite number of states, inputs and outputs). A machine table of this sort describes the operation of a deterministic automaton, but most machine state functionalists (e.g. Putnam 1967) take the proper model for the mind to be that of a probabilistic automaton: one in which the program specifies, for each state and set of inputs, the probability with which the machine will enter some subsequent state and produce some particular output
THE VERY IDEA OF TURING MACHINE Alan mathison Turing, OBE, FRS(/'tjuorin TEWR-ing; 23 June 1912-7 June 1954), was an English mathematician, logici an, cryptanalyst, and computer scientist. He was highly influential in the development of computer science. providing a formalisation of the concepts of" algorithm"and computation"with the Turing machine, which played a significant role in the creation of the modern computer
THE VERY IDEA OF TURING MACHINE Alan Mathison Turing, OBE, FRS ( /ˈtjʊərɪŋ / TEWR-ing; 23 June 1912 – 7 June 1954), was an English mathematician, logici an, cryptanalyst, and computer scientist. He was highly influential in the development of computer science, providing a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which played a significant role in the creation of the modern computer
THE VERY IDEA OF TURING MACHINE A Turing machine is a device that manipulates symbols on a strip of tape to simulatethe logic of any computer algorithm, an dis particularly useful ip% mated according to a table of rules. Despite its simplicity, a Turing machine can be explaining the functions of a CPU inside a computer. The "turing washe Turingmachine is not intended as a practical computing technology, but rather as a hypothetical device representing a computing machine. Turing machines help computer scientists understand the limits of mechanical computation Turing gave a succinct definition of the experiment in his 1948 essay, Intelligent Machinery. Referring to his 1936 publication, Turing wrote that the Turing machine, here called a Logical Computing Machine, consisted of: an infinite memory capacity obtained in the form of an infinite tape marked out into squares, on each of which a symbol could be printed. At any moment there is one symbol in the machine; it is called the scanned symbol The machine can alte the scanned symbol and its behavior is in part determined by that symbol, but the symbols on the tape elsewhere do not affect the behaviour of the machine. However the tape can be moved back and forth through the machine, this being one of the elementary operations of the machine. Any symbol on the tape may therefore eventually have an innings. (Turing 1948, p. 61)
THE VERY IDEA OF TURING MACHINE A Turing machine is a device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a computer. The "Turing" machine was described by Alan Turing in 1936,[1] who called it an "a(utomatic)-machine". The Turing machine is not intended as a practical computing technology, but rather as a hypothetical device representing a computing machine. Turing machines help computer scientists understand the limits of mechanical computation. Turing gave a succinct definition of the experiment in his 1948 essay, "Intelligent Machinery". Referring to his 1936 publication, Turing wrote that the Turing machine, here called a Logical Computing Machine, consisted of: ...an infinite memory capacity obtained in the form of an infinite tape marked out into squares, on each of which a symbol could be printed. At any moment there is one symbol in the machine; it is called the scanned symbol. The machine can alter the scanned symbol and its behavior is in part determined by that symbol, but the symbols on the tape elsewhere do not affect the behaviour of the machine. However, the tape can be moved back and forth through the machine, this being one of the elementary operations of the machine. Any symbol on the tape may therefore eventually have an innings.[2] (Turing 1948, p. 61)
More precisely, a Turing machine consists of A tape which is divided into cells, one next to the other. Each cell contains a symbol from some finite alphabet. The alphabet contains a special blank symbol (here written as 'B)and one or more other symbols. The tape is assumed to be arbitrarily extendable to the left and to the right, ie, the Turing machine is always supplied with as much tape as it needs for its computation. Cells that have not been written to before are assumed to be filled with the blank symbol. In some models the tape has a left end marked with a special symbol; the tape extends or is indefinitely extensible to the right A head that can read and write symbols on the tape and move the tape left and right one (and only one) cell at a time In some models the head moves and the tape is stationary. A finite table(occasionally called an action table ortransition function of instructions (usually quintuples [5 tuples]: qia;dk, but sometimes 4-tuples)that, given thestate( qi) the machine is currently in and the symbol(ai )it is reading on the tape(symbol currently under the head) tells the machine to do the following in sequence(for the 5 tuple models) o Either erase or write a symbol (instead of ai, write ai1), and then o Move the head (which is described by dk and can have values: ' L' for one step left or'R' for one step rightor N for staying in the same place), and then o Assume the same or a new state as prescribed (go to state qin) In the 4-tuple models, erase or write a symbol (ain )and move the head left or right (dk)are specified as separate instructions. Specifically, the table tells the machine to (ia) erase or write a symbol or (ib)move the head left or machine v rill halt; other models require all entries to be filled. A state register that stores the state of the Turing machine, one of finitely many. There is one specialstart state with which the state register is initialized. These states, writes Turing, replace the"state of mind"a person performing computations would ordinarily be in
More precisely, a Turing machine consists of: A tape which is divided into cells, one next to the other. Each cell contains a symbol from some finite alphabet. The alphabet contains a special blank symbol (here written as 'B') and one or more other symbols. The tape is assumed to be arbitrarily extendable to the left and to the right, i.e., the Turing machine is always supplied with as much tape as it needs for its computation. Cells that have not been written to before are assumed to be filled with the blank symbol. In some models the tape has a left end marked with a special symbol; the tape extends or is indefinitely extensible to the right. A head that can read and write symbols on the tape and move the tape left and right one (and only one) cell at a time. In some models the head moves and the tape is stationary. A finite table (occasionally called an action table ortransition function) of instructions (usually quintuples [5- tuples] : qiaj→qi1aj1dk , but sometimes 4-tuples) that, given thestate(qi ) the machine is currently in and the symbol(aj ) it is reading on the tape (symbol currently under the head) tells the machine to do the following in sequence (for the 5- tuple models): Either erase or write a symbol (instead of aj , write aj1 ),and then Move the head (which is described by dk and can have values: 'L' for one step left or 'R' for one step rightor 'N' for staying in the same place), and then Assume the same or a new state as prescribed (go to state qi1 ). In the 4-tuple models, erase or write a symbol (aj1 ) and move the head left or right (dk) are specified as separate instructions. Specifically, the table tells the machine to (ia) erase or write a symbol or (ib) move the head left or right, and then (ii) assume the same or a new state as prescribed, but not both actions (ia) and (ib) in the same instruction. In some models, if there is no entry in the table for the current combination of symbol and state then the machine will halt; other models require all entries to be filled. A state register that stores the state of the Turing machine, one of finitely many. There is one specialstart state with which the state register is initialized. These states, writes Turing, replace the "state of mind" a person performing computations would ordinarily be in
THIS IS A MACHINE TABLE aDditional details required to visualize or implement Turing machines State table for 3 state, 2 symbol busy beaver Current state a Current state B Current state c Tape write MoveNextWrite Write Move Next symbo sambo tape state tape state1 symbo Move Next tape state O1RB1LA1LB HAL 1 R B R T
THIS IS A MACHINE TABLE State table for 3 state, 2 symbol busy beaver Tape symbo l Current state A Current state B Current state C Write symbo l Move tape Next state Write symbo l Move tape Next state Write symbo l Move tape Next state 0 1 R B 1 L A 1 L B 1 1 L C 1 R B 1 R HAL T [edit]Additional details required to visualize or implement Turing machines
团工具塑·口 4第11-12屏供共81屏 1迅副7)视密选项,X 假设一台筒化的图灵机只有两种內部状态:“快乐”和“悲伤”。它 也只能识别出三种符号:椭圆形、矩形和月矛形(但它不会在意各种矩 系统按照图灵机表选行按部就班的操作之后(操作过略),会在莱 形、椭圆形和月牙形之间的差别,并把圆看成是椭圆的一个特例)。在 时刻“停机”,并提交这样的输出行 这里,月牙形代表了一个具体的问题的边界。整台机器的困灵机表可以 是这样的: 《≤ 內部状态为“悲伤” 内部状态为“快 读入椭圆删除读入符号,打印椭圆,右移一格,删除读入符号 快 继续“悲伤” 打印月牙形,尔 后停机 读入矩形「删除读入符号,打印图,右移一格 继续“悲伤 图0-2图灵机的加法运算(停机状态) 读入月牙删除读入符号,左移一格,打印月牙 形 形,转为“快乐” 如果把这里我们看到的圆形释为最小的自然数单位“1”,并把短 表0-1图灵机的加法机表 形解榉为“加”的话,上面所呈现出来的图灵机,实质上就是一台加法 机。上面所展示的具体运算,就是“二加一等于三。很显然,这种“加 现在就假设读写头(用三角形表示)面对的是这样一段输入: 法机”的功能非常单一,它自身是无力模拟各种计算方式的。而要向“模 拟各种计算函数”的方向继续迈步,就得引入“图灵机”概念的衍生 《 万能图灵机( Universal Turing Machine,筒称UM):假设有这样 台困灵机,其图灵机表所包含的指导规则允许系统本身模拟任何一个其 它的图灵机的行为,那么这样的图灵机就是一台UM。UTM乃是今天 我们的市售计算机的数学抽象。原则上说,UM的具有这梯的功能(此 伤 功能由下述论题所表达) 图0-1图灵机的加法运算(初始状态)
Multiple realizability多重可实现性 An important part of some accounts of functionalism is the idea of multiple realizability. Since, according to standard functionalist theories, mental states are the corresponding functional role mental states can be sufficiently explained without taking into account the underlying physical medium(e.g. the brain, neurons etc. that realizes such states; one need only take into account the higher-level functions in the cognitive system. Since mental states are not limited to a particular medium, they can be realized in multiple ways, including theoretically, within non-biological systems, such as computers. In other words, a silicon-based machine could, in principle, have the same sort of mental life that a human being has, provided that its cognitive system realized the proper functional roles. Thus, mental states are individuated much like a valve; a valve can be made of plastic or metal or whatever material, as long as it performs the proper function(say, controlling the flow of liquid through a tube by blocking and unblocking its pathway)
Multiple realizability多重可实现性 An important part of some accounts of functionalism is the idea of multiple realizability. Since, according to standard functionalist theories, mental states are the corresponding functional role, mental states can be sufficiently explained without taking into account the underlying physical medium (e.g. the brain, neurons, etc.) that realizes such states; one need only take into account the higher-level functions in the cognitive system. Since mental states are not limited to a particular medium, they can be realized in multiple ways, including, theoretically, within non-biological systems, such as computers. In other words, a silicon-based machine could, in principle, have the same sort of mental life that a human being has, provided that its cognitive system realized the proper functional roles. Thus, mental states are individuated much like a valve; a valve can be made of plastic or metal or whatever material, as long as it performs the proper function (say, controlling the flow of liquid through a tube by blocking and unblocking its pathway)