意识:此处,彼处和处处?

Consciousness:Here,There and Everywhere?

意识科学通过关注体验的行为相关物和神经相关物(Behavioural and Neuronal Correlates of Experience)已经取得了长足进步。就取得的这些进步而言,尽管这些相关物(即行为相关物和神经相关物的简称)是重要的,但如果我们要理解哪怕最基本的事实(例如,尽管小脑具有更多的神经元,而且几乎表现得与大脑皮层一样复杂,却为什么大脑皮层产生了意识,而小脑没有),那么它们还不够。此外,在许多情况下,如我们想要知道意识是否存在时,相关物几乎没有任何帮助。例如,对那些只残存几块功能皮层区的患者、早产儿、非哺乳类物种以及在驾驶、人脸识别和回答难题方面正迅速超越人类的机器而言。要解决这些问题,我们不仅需要更多的数据也需要一个意识理论——一个表明体验是什么以及哪类物理系统可能拥有体验的理论。整合信息理论(Integrated Information Theory,IIT)就是这样的理论,它以体验本身为起点,包含五个现象学公理:内在存在、构成、信息、整合和排他。IIT从上述五个公理导出五个公设,这些公设与支撑意识的物理机制所需的属性相关。IIT对个人体验(感受质)的量与质都提出了原则解释,并提供了一种计算方法来评估一个特定的物理系统是否有意识以及意识到了什么。此外,IIT可以解释一系列临床发现和实验室研究,做出一些可检验的预测,并推断出一些尚有问题的情况。这个理论认为,意识是具有特定因果属性的物理系统所拥有的一种基本属性。它预测意识是有等级的,是在生物有机体中普遍存在的,以及能出现在一些非常简单的系统中。反过来,它也预测前馈网络——即便是复杂的前馈网络——是无意识的,并且像个体组成的群体或一堆沙子这样的聚集物也没有意识。IIT与通常的功能主义信念形成鲜明对比,因为IIT表明:即使数字计算机的行为在功能上与我们的一样,即使它们如实地模拟人脑的运行,但它们仍然缺乏体验。

The science of has made great strides by focusing on the behavioural and neuronal correlates of exporience. However, while such correlates are important for progress to occur, they are not enough if we are to understand even basic facts, for example, why the cerebral cortex gives rise to consciousness but the cerebellum does not, though it has even more neurons and appears to be just as complicated. Moreover, correlates are of little help in many instances where we would like to know if consciousness is present： patients with a few remaining islands of functioning cortex, preterm infants, non-mammalian species and machines that are rapidly outperforming people at driving, recognizing faces and objects, and answering difficult questions. To address these issues, we need not only more data but also a theory of consciousness that says what experience is and what type of physical systems can have it. Integrated information theory （liT） does so by starting from experience itself via five phcnomenological axioms： intrinsic existence, composition, information, integration and exclusion. From these it derives five postulates about the properties required of physical mechanisms to support consciousness. The theory provides a principled account of both the quantity and the quality of an individual experience （a quale）, and a calculus to evaluate whether or not a particular physical system is conscious and of what. Moreover, liT can explain a range of clinical and laboratory findings, makes a number of testable predictions and extrapolates to a number of problematic conditions. The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. It predicts that consciousness is graded, is common among biological organisms and can occur in some very simple systems. Conversely, it predicts thatfeed-forward networks, even complex ones, are not conscious, nor are aggregates such as groups of individuals or heaps of sand. Also, in sharp contrast to widespread functionalist beliefs, liT implies that digital computers, even if their behaviour were to be functionally equivalent to ours, and even if they were to run faithful simulations of the human brain, would experience next to nothing.