The adaptive markets hypothesis--论文代写范文精选

在这一过程中,我们可以充分协调有效市场假说与行为选择,导致一个新的观点，适应性市场假说。约瑟夫对商业周期的看法,企业家和资本主义有一个明确的进化思想理论。下面的paper代写范文对这一理论进行了阐述。

Abstract
The methodological differences between mainstream and behavioural economics suggest that an alternative to the traditional deductive approach of neoclassical economics may be necessary to reconcile the EMH with its behavioural critics. One particularly promising direction is to view financial markets from a biological perspective and, specifically, within an evolutionary framework in which markets, instruments, institutions and investors interact and evolve dynamically according to the ‘law’ of economic selection. Under this view, 15 financial agents compete and adapt, but they do not necessarily do so in an optimal fashion (see Farmer and Lo, 1999; Farmer, 2002; Lo, 2002; 2004; 2005). 

This evolutionary approach is heavily influenced by recent advances in the emerging discipline of ‘evolutionary psychology’, which builds on the seminal research of E.O. Wilson (1975) in applying the principles of competition, reproduction, and natural selection to social interactions, yielding surprisingly compelling explanations for certain kinds of human behaviour, such as altruism, fairness, kin selection, language, mate selection, religion, morality, ethics and abstract thought (see, for example, Barkow, Cosmides and Tooby, 1992; Gigerenzer, 2000). ‘Sociobiology’ is the rubric that Wilson (1975) gave to these powerful ideas, which generated a considerable degree of controversy in their own right, and the same principles can be applied to economic and financial contexts. 

In doing so, we can fully reconcile the EMH with all of its behavioural alternatives, leading to a new synthesis: the adaptive markets hypothesis (AMH). Students of the history of economic thought will no doubt recall that Thomas Malthus used biological arguments – the fact that populations increase at geometric rates whereas natural resources increase at only arithmetic rates – to arrive at rather dire economic consequences, and that both Darwin and Wallace were influenced by these arguments (see Hirshleifer, 1977, for further details). Also, Joseph Schumpeter’s view of business cycles, entrepreneurs and capitalism have an unmistakeable evolutionary flavour to them; in fact, his notions of ‘creative destruction’ and ‘bursts’ of entrepreneurial activity are similar in spirit to natural selection and Eldredge and Gould’s (1972) notion of ‘punctuated equilibrium’. 

More recently, economists and biologists have begun to explore these connections in several veins: direct extensions of sociobiology to economics (Becker, 1976; Hirshleifer, 1977); evolutionary game theory (Maynard Smith, 1982); evolutionary economics (Nelson and Winter, 1982); and economics as a complex system (Anderson, Arrow and Pines, 1988). And publications like the Journal of Evolutionary Economics and the Electronic Journal of Evolutionary Modeling and Economic Dynamics now provide a home for research at the intersection of economics and biology. Evolutionary concepts have also appeared in a number of financial contexts. For example, Luo (1995) explores the implications of natural selection for futures markets, and Hirshleifer and Luo (2001) consider the long-run prospects of overconfident traders in a competitive securities market. 

The literature on agent-based modelling pioneered by Arthur et al. (1997), in which interactions among software agents programmed with simple heuristics are simulated, relies heavily on evolutionary dynamics. And at least two prominent 16 practitioners have proposed Darwinian alternatives to the EMH. In a chapter titled ‘The Ecology of Markets’, Niederhoffer (1997, ch. 15) likens financial markets to an ecosystem with dealers as ‘herbivores’, speculators as ‘carnivores’, and floor traders and distressed investors as ‘decomposers’. And Bernstein (1998) makes a compelling case for active management by pointing out that the notion of equilibrium, which is central to the EMH, is rarely realized in practice and that market dynamics are better explained by evolutionary processes. 

Clearly the time is now ripe for an evolutionary alternative to market efficiency. To that end, in the current context of the EMH we begin, as Samuelson (1947) did, with the theory of the individual consumer. Contrary to the neoclassical postulate that individuals maximize expected utility and have rational expectations, an evolutionary perspective makes considerably more modest claims, viewing individuals as organisms that have been honed, through generations of natural selection, to maximize the survival of their genetic material (see, for example, Dawkins, 1976). While such a reductionist approach can quickly degenerate into useless generalities – for example, the molecular biology of economic behaviour – nevertheless, there are valuable insights to be gained from the broader biological perspective. 

Specifically, this perspective implies that behaviour is not necessarily intrinsic and exogenous, but evolves by natural selection and depends on the particular environmental through which selection occurs. That is, natural selection operates not only upon genetic material but also upon social and cultural norms in homo sapiens; hence Wilson’s term ‘sociobiology’. To operationalize this perspective within an economic context, consider the idea of ‘bounded rationality’ first espoused by Nobel-prize-winning economist Herbert Simon. Simon (1955) suggested that individuals are hardly capable of the kind of optimization that neoclassical economics calls for in the standard theory of consumer choice. 

Instead, he argued that, because optimization is costly and humans are naturally limited in their computational abilities, they engage in something he called ‘satisficing’, an alternative to optimization in which individuals make choices that are merely satisfactory, not necessarily optimal. In other words, individuals are bounded in their degree of rationality, which is in sharp contrast to the current orthodoxy – rational expectations – where individuals have unbounded rationality (the term ‘hyper-rational expectations’ might be more descriptive). Unfortunately, although this idea garnered a Nobel Prize for Simon, it had relatively little impact on the economics profession. (However, his work is now receiving greater attention, thanks in part to the growing behavioural literature in economics and finance. 

See, for example, Simon, 1982; 17 Sargent, 1993; A. Rubinstein, 1998; Gigerenzer and Selten, 2001.) Apart from the sociological factors discussed above, Simon’s framework was commonly dismissed because of one specific criticism: what determines the point at which an individual stops optimizing and reaches a satisfactory solution? If such a point is determined by the usual cost–benefit calculation underlying much of microeconomics (that is, optimize until the marginal benefits of the optimum equals the marginal cost of getting there), this assumes the optimal solution is known, which would eliminate the need for satisficing. As a result, the idea of bounded rationality fell by the wayside, and rational expectations has become the de facto standard for modelling economic behaviour under uncertainty. An evolutionary perspective provides the missing ingredient in Simon’s framework. 

The proper response to the question of how individuals determine the point at which their optimizing behaviour is satisfactory is this: such points are determined not analytically but through trial and error and, of course, natural selection. Individuals make choices based on past experience and their ‘best guess’ as to what might be optimal, and they learn by receiving positive or negative reinforcement from the outcomes. If they receive no such reinforcement, they do not learn. In this fashion, individuals develop heuristics to solve various economic challenges, and, as long as those challenges remain stable, the heuristics will eventually adapt to yield approximately optimal solutions to them. If, on the other hand, the environment changes, then it should come as no surprise that the heuristics of the old environment are not necessarily suited to the new. In such cases, we observe ‘behavioural biases’ – actions that are apparently ill-advised in the context in which we observe them. But rather than labelling such behaviour ‘irrational’, it should be recognized that suboptimal behaviour is not unlikely when we take heuristics out of their evolutionary context. (paper代写)

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