I found Populism: A Very Short Introduction by Cas Mudde and Cristobal Rovira Kaltwasser to be very useful and conceptually clear, a worthy addition to Oxford’s charming Very Short Introductions series.
The real contribution of the book is that it provides a definition of populism that is both conceptually clear and empirically useful–no mean feat. Here it is:
We define populism as a thin-centered ideology that considers society to be ultimately separated into two homogeneous and antagonistic camps, “the pure people” versus “the corrupt elite,” and which argues that politics should be an expression of the general will of the people. …
Populism must be understood as a kind of mental map through which individuals analyze and comprehend political reality. It is not so much a coherent ideological tradition as a set of ideas that, in the real world, appears in combination with quite different, and sometimes contradictory, ideologies.
The points that populism is a set of ideas but not exactly an ideology, and that those ideas can mesh with both left-wing and right-wing political programs, seem to me clearly true. A lot of writing about populism or populist phenomena considers it to have some essential nature, but what I think this book is good at is showing how “thin” that essential nature is, and therefore how flexible and various populism is in practice.
The book is also good at explaining the relationship between democracy and populism, another fraught topic of late:
Populism is essentially democratic, but at odds with liberal democracy, the dominant model in the contemporary world. Populism holds that nothing should constrain “the will of the (pure) people” and fundamentally rejects the notions of pluralism and, therefore, minority rights as well as the “institutional guarantees” that should protect them. In practice, populists often invoke the principle of popular sovereignty to criticize those independent institutions seeking to protect fundamental rights that are inherent to the liberal democratic model. Among the most targeted institutions are the judiciary and the media.
In sum, I found the book to be a helpful aid in getting closer to an objective understanding of our present moment.