Personal identityPersonal identity is the unique numerical identity of a person over time. Discussions regarding personal identity typically aim to determine the necessary and sufficient conditions under which a person at one time and a person at another time can be said to be the person, persisting through time. In philosophy, the problem of personal identity is concerned with how one is able to identify a single person over a time interval, dealing with such questions as, "What makes it true that a person at one time is the same thing as a person at another time?" or "What kinds of things are we persons?" In contemporary metaphysics, the matter of personal identity is referred to as the diachronic problem of personal identity.
SelfIn philosophy, the self is the relationship of an individual’s own being, knowledge and values. Self relates the experiences of one's inner and outer living in presence. The first-person perspective distinguishes selfhood from personal identity. Whereas "identity" is (literally) sameness and may involve categorization and labeling, selfhood implies a first-person perspective and suggests potential uniqueness. Conversely, "person" is used as a third-person reference.
Psychology of selfThe psychology of self is the study of either the cognitive, conative or affective representation of one's identity, or the subject of experience. The earliest formulation of the self in modern psychology derived from the distinction between the self as I, the subjective knower, and the self as Me, the object that is known. Current views of the self in psychology position the self as playing an integral part in human motivation, cognition, affect, and social identity.
Thought experimentA thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences. The ancient Greek deiknymi, "was the most ancient pattern of mathematical proof", and existed before Euclidean mathematics, where the emphasis was on the conceptual, rather than on the experimental part of a thought-experiment. Johann Witt-Hansen established that Hans Christian Ørsted was the first to use the term Gedankenexperiment (from German: 'thought experiment') circa 1812.
