Regulæ ad directionem ingenii ut et inquisitio veritatis per lumen naturale

The dictionary definitions of the word consciousness extend through several centuries and reflect a range of seemingly related meanings, with some differences that have been controversial, such as the distinction between 'inward awareness' and 'perception' of the physical world, or the distinction between 'conscious' and 'unconscious', or the notion of a "mental entity" or "mental activity" that is not physical.

A partisan definition such as Sutherland's can hugely affect researchers' assumptions and the direction of their work:

Most writers on the philosophy of consciousness have been concerned with defending a particular point of view, and have organized their material accordingly. For surveys, the most common approach is to follow a historical path by associating stances with the philosophers who are most strongly associated with them, for example, Descartes, Locke, Kant, etc. An alternative is to organize philosophical stances according to basic issues.

Mental processes (such as consciousness) and physical processes (such as brain events) seem to be correlated, however the specific nature of the connection is unknown.

Schema of the neural processes underlying consciousness, from Christof Koch