The threshold of self-consciousness

This thesis is about self-consciousness and how we might be able to determine its existence in non-human animals and human infants. By 'self-consciousness' I mean something very like the type of self-consciousness possessed by normal human adults. I examine the nature of self-consciousness, explore the connection between self-consciousness and concept possession, and review research into animal and infant self-consciousness. I conclude that there are ways to determine the existence of self-consciousness in animals based on observations of their behaviour, and that sufficient evidence exists to conclusively ascribe self-consciousness to chimpanzees. Furthermore, there are strong indications that self-consciousness is probably possessed by dolphins, elephants and some corvid species such as magpies and scrub jays. This thesis is divided into two main parts. Part 1 (chapters 1-4) is mostly theoretical. In part 1 I discuss the nature of self-consciousness and how we can tell it is possessed by an organism. Part 2 (chapters 5-8) applies this analysis in the evaluation of various research paradigms on self-consciousness in animals and human infants. I conclude the thesis with chapter 9, in which I summarise the main arguments and conclusions presented and offer some thoughts about future research. In chapter 1 I define and defend my conception self-consciousness, which I encapsulate as an understanding of one's own existence as a psychological subject with intentional agency. I also briefly review several research paradigms and foreshadow the conclusions reached in part 2. In chapter 2 I explore some central issues in the philosophy of self-consciousness and find a common thread, a Fundamental Dichotomy between relationalism, which sees self-consciousness as always involving a relation between a subject and a mental state, and intrinsicism, which regards self-consciousness as immediate and unmediated. Relationalism is the correct position for a self-concept while intrinsicism holds only for non-conceptual self-access. This position suggests the hypothesis that concept possession alone is sufficient for self-consciousness. I explain and defend this hypothesis in chapter 3 and suggest that it provides a yardstick for gauging the validity of research into self-consciousness. In chapter 4 I discuss ways in which concept possession might be determined: propositional thinking, rationality and symbol-mindedness are all indicators of concept possession. These are difficult to conclusively determine since I advocate that we must keep the standard of evidence high. Nevertheless, in a few studies there is good reason to believe that the standard has been met, as discussed in Part 2. The Concept Possession Hypothesis (CPH) may be considered controversial by some readers. Nevertheless, I do not rely on it exclusively in part 2 and readers who remain unconvinced by the hypothesis will still find much of interest in part 2. In chapter 5 I use CPH to argue that chimpanzees are self-conscious on the basis of their being demonstrably concept possessing. An interim conclusion is that chimpanzees are symbol-minded, which is significant in its own right. In chapter 6 I evaluate the various paradigms for studying imitation and conclude that selective imitation is evidence of theory of mind and hence self-consciousness, a conclusion that is consistent with CPH. Chapter 7 is devoted to exploring the connection between memory and self-consciousness and, based on episodic memory studies, I come to the conclusion that there is good evidence that scrub jays are self-aware. In chapter 8 I concentrate on one species, rats, and examine a range of research paradigms purporting to demonstrate rat rationality. Detailed analyses of these experiments leads me to conclude that rationality need not be invoked to explain the results, which can all be accounted for using associative and other non-conceptual theories.