All scientific work is incomplete – whether it be observational or experimental.

All scientific work is incomplete – whether it be observational or experimental. All scientific work is liable to be upset or modified by advancing knowledge. That does not confer upon us a freedom to ignore the knowledge we already have, or to postpone the action that it appears to demand at a given time. Hill, Austin Bradford (1965). The Environment and Disease: Association or Causation? p. 300