||In the fairly strict sense understood here, the idea of a research program(me) was introduced and developed by Imre Lakatos in a number of papers in the late 1960's and early 1970's. Lakatos may be seen as seeking some sort of reconciliation of the views of Karl Popper and Thomas Kuhn. Lakatos characterized research programs as consisting of a hard core of central theoretical principles or laws, surrounded by a protective belt of auxiliary hypotheses. Research programs are series or sequences of theories which are connected by the hard core of the program which all members of the program share. The hard core of a research program is not open to modification. However, the protective belt may be altered, and changes to the protective belt constitute shifts between different phases of the research program. Research programs are capable of making progress in a theoretical sense when they make predictions, as well as in an empirical sense when the predictions are confirmed. Programs are evaluated in terms of their progressiveness, and a rational choice between competing programs is made on the basis of comparative judgements of progress. In some respects, Lakatos's idea of a research programme is intended as a refinement of Kuhn's idea of a paradigm. Larry Laudan later developed a related proposal with his notion of a research tradition.