INTRODUCTION

I-thoughts are thoughts about one's own mental states or about “oneself” in some sense (Bennett [1988]). They are closely linked to what psychologists call “metacognition”: that is, cognitions about other cognitions or mental representations (Metcalfe and Shimamura [1994]; Koriat [2007]). There seems to be growing evidence that many animals are indeed capable of having I-thoughts as well as having the ability to understand the mental states of others (Hurley and Nudds [2006]; Terrace and Metcalfe [2005]).

There is also a relevant philosophical theory of consciousness: namely, the higher-order thought (HOT) theory of consciousness which says that what makes a mental state conscious is the presence of a suitable higher-order thought about that state (Gennaro [2004a]; Rosenthal [2005]). For various reasons, such thoughts are typically understood to take the form “I am in mental state M now.” A higher-order thought, then, is a kind of metacognition. It is a mental state directed at another mental state. So, for example, my desire to write a good book chapter becomes conscious when I am (non-inferentially) “aware” of the desire. Intuitively, it seems that conscious states, as opposed to unconscious ones, are mental states that I am “aware of” in some representational sense (Lycan [2001]). In a case of subliminal perception, I am not aware that I am in that perceptual state. Thus, it is unconscious. However, when I become aware that I am having that perception, it becomes conscious.