David Rosenthal is an American philosopher who has made significant contributions to the philosophy of mind, particularly in the area of consciousness and related topics.  He is professor of philosophy at the Graduate Center of the City University of New York (CUNY).  He was educated at the University of Chicago and then Princeton University.  Rosenthal also has research interests in cognitive science, and is Coordinator of the CUNY Graduate Center's Interdisciplinary Concentration in Cognitive Science.  And he has done work in philosophy of language, metaphysics, ancient philosophy, and 17th-century rationalism.

Rosenthal is a founding member and past president (2008) of the Association for the Scientific Study of Consciousness.

Rosenthal is best known for his higher-order-thought (HOT) theory of consciousness.  A mental state is never conscious if one is in no way aware of that state.  So Rosenthal argues that we can best explain what it is for a mental state to be conscious by appeal to one's being aware of that state in a suitable way.  Consciousness is a matter of how one's mental life subjectively appears to one; one's awareness of one's mental states constitutes that mental appearance (Rosenthal 2022).

Rosenthal's account of consciousness must then specify the way one is aware of a mental state when that state is conscious.  He argues that this awareness consists in a thought that one is in that state. These higher-order thoughts (HOTs) constitute the mental appearance of consciousness, and so suffice for there to be something it is like for to be in various conscious states.  HOTs are distinct from the states they make one aware of.  Also, HOTs are rarely themselves conscious, and they never result from any conscious inference.  So HOTs make it appear subjectively that our awareness of our conscious states is direct and transparent.

Because consciousness is a psychological phenomenon, any explanation of what it is for a mental state to be conscious must primarily be cast in psychological terms.  And on pain of an uninformative circularity, an explanation cannot appeal to psychological phenomena that are themselves conscious.  HOTs satisfies these constraints, since HOTs are psychological occurrences that are rarely conscious.  Because HOTs are seldom conscious, we know about them not from first-person access, but because they are theoretical posits whose occurrence is established by their significant explanatory role.

The standard way to tell whether a mental state is conscious, both in everyday contexts and in experimental work, is that an individual can report being in the state without relying on any conscious inference.  So Rosenthal argues that, for creatures with the relevant linguistic ability, a state's being conscious involves the ability to report that state.  Also, a report always expresses a thought with the same content as the report, and in this case the thought is a HOT.  So Rosenthal also argues that the role of reporting provides compelling reason to see our subjective awareness of our conscious states as consisting in HOTs (Rosenthal 2005, ch. 2).

Rosenthal has also argued that positing HOTs enables us to explain various things we could not explain in any other way.  One striking example is why thoughts are always conscious when they are verbally expressed (Rosenthal 2005, ch. 10); another example is why the so-called essential indexical appears to be irreducible, along with other features of the awareness and identification of the self (Rosenthal 2012).  Rosenthal has also argued that the HOT theory fits well with recent findings in psychology and neuroscience (e.g., Lau and Rosenthal 2011).

It is often claimed in the literature in philosophy that qualitative mental properties are intrinsically conscious, and cannot occur without being conscious.  Rosenthal rejects that claim, and has developed a positive account of qualitative consciousness that is thoroughly realist about conscious mental qualities, but explains what mental qualities are independently of consciousness.  That fits well with HOT theory, on which a state's being conscious is never an intrinsic property of that state.  But Rosenthal argues for his account of mental qualities independently of HOT theory (Rosenthal, 2005. chs. 5–7; 2015).