Here is a brief talk that I gave at the University of Queensland in Brisbane (25 October 2018). It accompanies a blog post  Evidence-based policymaking and the new policy sciences [and powerpoint ppt]:
"In the ‘new policy sciences’, Chris Weible and I advocate:

a return to Lasswell’s vision of combining policy analysis (to recommend policy change) and policy theory (to explain policy change), but
focusing on a far larger collection of actors (beyond a small group at the centre),
recognising new developments in studies of the psychology of policymaker choice, and
building into policy analysis the recognition that any policy solution is introduced in a complex policymaking environment over which no-one has control.

However, there is a lot of policy theory out there, and we can’t put policy theory together like Lego to produce consistent insights to inform policy analysis.
Rather, each concept in my image of the policy process represents its own literature: see these short explainers on the psychology of policymaking, actors spread across multi-level governance, institutions, networks, ideas, and socioeconomic factors/ events.
What the explainers don’t really project is the sense of debate within the literature about how best to conceptualise each concept. You can pick up their meaning in a few minutes but would need a few years to appreciate the detail and often-fundamental debate.
Ideally, we would put all of the concepts together to help explain policymaker choice within a complex policymaking environment (how else could I put up the image and present is as one source of accumulated wisdom from policy studies?)."
... see the post for more, and use the powerpoint to read along if you like.