A method for retrodicting source-rock quality and/or paleoenvironmental conditions are disclosed. A first set of system variables associated with source-rock quality is selected (705). A second set of system variables directly or indirectly causally related to the first set of variables is also selected (710). Data for variables selected to be known quantities are estimated or obtained (720). A network with nodes including both sets of variables is formed (715). The network has directional links connecting interdependent nodes (715). The directional links preferably honor known causality relations. A Bayesian network algorithm is used with the data to solve the network for the unknown variables and their associated uncertainties (725). The variables selected to be unknowns can be input nodes (paleoenvironmental conditions), intermediate nodes, output nodes (source rock quality), or any combination thereof.