The philosophical study of well-being concerns what makes lives good for their subjects. It is now standard among philosophers to distinguish between two kinds of well-being:· lifetime well-being, i.e., how good a person’s life was for him or her considered as a whole, and· temporal well-being, i.e., how well off someone was, or how they fared, at a particular moment in time (momentary well-being) or over a period of time longer than a moment but shorter than a whole life, say, a day, month, yea