adapted from Linstone 1981
| proponent | Life span | description |
| Locke | 1632 to 1704 | empirical; agreement on observation and data |
| Leibniz | 1646 to 1716 | theoretical, truth is really in the analytical description, the truth doesn't depend on any particular data set |
| Kant | 1724 to 1804 | theoretical and empirical data complement each other, truth is in the synthesis, the synergism of multiple models |
| Hegel | 1770 to 1831 | dialectic confrontaion between models or plans leading to resolution |
| Merleau-Ponty | 1908 to 1961 | reality is currently shared assumptions about a specific situation |