This PDF-format paper looks at varying aging theories and what they might mean for the prospects of developing medical technologies to halt or reverse age-related degeneration. "The feasibility of developing any such treatment depends on the existence of common factors involved in causing many or most of the manifestations. Further, in order to be 'treatable' a factor would need to be sufficiently independent of any function that we need to live happily in order that altering the factor did not cause significant adverse effects. Few would want an anti-aging treatment that resulted in blindness or some other major side-effect. The potential for the existence of treatable common factors is highly dependent on aging theories. Depending on which theory you believe, the likelihood of finding such factors ranges from 'impossible' to 'very probable'."