This final chapter concludes by pointing out that the two main scholarly contributions of this book are the result of trying to bring both intellectual history and politics back into political science research. First, the book draws on insights from the discipline of intellectual history to show how the meaning and content of “left” and “right,” and “liberal” and “conservative,” are constantly changing. Once we recognize this, we can stop making incoherent claims about politicians, groups, and parties moving “left” and “right” or becoming more or less “liberal” and “conservative” over time. If we do that, we may even give up on the left-right, liberal-conservative, ideological spectrum altogether. This potential change in language and modes of thinking could make our society a more civil, less combative, and less polarized place to live. Second, the book shows how a political factor, party control of government, influences party ideology development. I identified nineteen instances of long-term change in party control of government institutions, and in sixteen of those cases, party ideologies developed as predicted by the political institutional theory.