What is a mental state? I believe to find an acceptable “What” to “a Mental state” definition, we need to start at the base roots of the very words allocated by human language to give understandable or sensible meaning. This has been separated into three distinct words.
Definition of “a”
A Relevant speech/language counterpart of orthographic “a”
Definition of “mental” – All found in Merriam-Webster
Of or relating to the mind; specifically: of or relating to the total emotional and intellectual response of an individual to external reality
• mental health
Of or relating to intellectual as contrasted with emotional activity
• mental acuity
Relating to, or being intellectual as contrasted with overt physical activity
• made quick mental calculations
Occurring or experienced in the mind: inner
• mental anguish
• a mental breakdown
Relating to the mind, its activity, or its products as an object of study: ideological
• mental science
Relating to spirit or idea as opposed to matter
• the distinction between physical things and mental ideas
Definition of “state” - relevant
Condition of mind or temperament.
• in a highly nervous state
Condition of abnormal tension or excitement.
Thus deducting from the aforementioned definitions “a mental state” would be time dependent due to the probability of change thus making the whole condition a variable of a specific frame of reference point, relating to the total emotional and intellectual response of an individual to external reality. An objective measurable state of emotional mental faculties can only be observed and calculated from an external point of view. An unknown amount of emotional dependencies exists subjectively within the individual that is impossible to measure by any means from the external, thus portions are extracted relating to the known thus giving limitational parameters constructed by the collective psychological views on Emotional and mental faculties of the mind. These together with the Time parameter is used to create a referenceable state that could be used in therapy when psycho analysing the origins that gave rise to the referenced.