G. Capano and M. Howlett, “Causal logics and mechanisms in policy design: How and why adopting a mechanistic perspective can improve policy design,” Public Policy and Administration, vol. 36, no. 2, pp. 141–162, Apr. 2021, doi: 10.1177/0952076719827068.

Policy solutions are comprised of policy instruments whose adoption is expected to be conducive to a desired outcome, with a policy design in turn composed of a mix of such tools expected to more or less comprehensively attain a set of goals.