here are both physical and mental states going on in space and time. We can always locate physical things, events and processes-they take place somewhere. Unlike physical states, mental states do not appear in physical space. Mental states are not visible to the public world and are only real in the sense that they occur in your experience. Physical objects, processes and events are all publicly observable while mental states are private to the individual and cannot be experienced by anyone other than the experiencer. Mental states are known from direct or immediate acquaintance.
Intentionality is the feature whereby many mental states posses a representational content. They seem to be about or directed upon other states of affairs. Some intentional states, such as beliefs, portray how the world actually is. If a the world is as a belief represents it as being, the belief is true, otherwise it is false. Other intentional states, such as desires and intentions, represents how a person wants the world to be. Desires and intentions that do not succeed in bringing about the state of affairs at which they are aimed are frustrated or unfulfilled. Sensations however lack intentionality. Sensations are not about anything else, they just are. Senses that lack intentionality are referred to as non-Intentional states.
Many philosophers, including John Searle, have claimed that intentional states are intrinsic to brains and are not derived from other intentional systems. Computer programs, by contrast, are not intrinsically about other states of affairs, and do not possess genuine underived intentionality. The contents of such programs only exist because we are there to interpret the programs. In a world without minds, things such as computer games would lack content, as would language, books and symbols in general.
It is difficult to try and regard Intentionality as a purely physical phenomenon. Casual Co-Variation claims that changes in your surroundings cause changes in your brain states. This is shown in the example of tree rings. The nature of a tree ring varies from year to year depending on what the weather is like.
Intentional states are holistic. They presupposes a whole network of other beliefs and because of prepositional content, they can be logically inconsistent with each-they can be rationally adjusted. Non-intentional states and physical states do not appear to be holistic. This is because they are atomistic, meaning that they stand alone and do not imply the existence or non-existence of anything else.
There is a difference between 1st and 3rd person perspectives which helps mark the difference between mental and physical states. To give a description of yourself you do not need to look at yourself in the mirror or study yourself in depth. You have automatic access to your thoughts and feelings. Another person wishing to describe you however does not have access to your thoughts and feeling and must therefore study your character in depth. They can only guess at what your mental belongings are as they are private to the individual and cannot be viewed by any test or scan.