It's become a commonplace of critical praise to claim that a book is necessary. Books that receive this supposed encomium are usually topical, obviously and evidently tied to an issue subject to heated discussion on twitter, late-night tv, and cable news. A necessary book has a clear, delineated point of view that expresses a politics that fits easily into our current political binary (liberal/conservative, Democrat/Republican, etc. etc.). It could be a novel with a protagonist who is transgender, or a refugee, it could be a polemic against a powerful figure, ideology, or institution, it could be a personal essay that dissects a traumatic experience. The critic who employs the word necessary is telegraphing his or her agreement with the political point of view of the book under review.
There's nothing inherently wrong with deeming a book necessary, but it's a word that, used without a consciousness of its purpose, says little to nothing about the book itself and much more about the reviewer and the reviewer's politics. It's a euphemism that signals a belonging to a particular club, a defensive deployment meant to shield the critic from attack in a deeply polarized climate dominated by quick outrage and increasingly quantified methods of critiquing literature, for instance, the starred rating rather than a complex analysis.
When the critic deems a book necessary, the label functions as a means of dividing the presumed readership of the book. Anyone who reads that a book about the mass incarceration of black Americans, for instance, is necessary, receives a signal not that the book has some crucial function to perform in the world (though it may or may not - the course of history will indicate whether or not it performs such a function), but rather that the book bolsters a political belief that he may or may not share. The reader who already feels outrage towards the situation of black Americans in prison will feel positively towards the book; the reader who believes that imprisoned black people fare no worse than white people will feel negatively. As a result, the first group may very well read the book, share the review on social media, or otherwise indicate support for it, while the second is unlikely to do those things, or might take an actively negative action, such as purposely giving the book low ratings on sites like Amazon and Goodreads. Any book with controversial or possibly inflammatory content, once it's reviewed within this critical economy of necessity, is subject to this binary (including books that attempt to critique, dismantle, or question the existence of a binary). If this demarcation sounds simplistic, that's because it is, but that is where the line is drawn by the word necessary.
It's a word that is nearly always meant positively, though its effects are anything but. It's a means of preaching to the choir. The problem is that necessary is so very rarely followed by the answers to the obvious questions: to whom? for what purpose? to what end? The critic takes for granted that the reader can answer those questions already, isolating the book among readers that are most likely to share its point of view. Instead of persuading individuals to allow themselves to be challenged and to question their immediate assumptions and opinions, the critic who talks of necessity presumes that not only is his point of view fundamentally correct, it needs no qualification and no explanation. Necessary is an encrypted word; decoded, it says: "Agree or you're wrong."
To demonstrate how important it is to follow up any description of a book as necessary with an explication of why, to whom, and for what purpose it is so, I will employ a highly inflammatory example: Mein Kampf is necessary. Now, if I were using the word necessary the way that it is most commonly used critically today, I would have just declared myself a Nazi. So I will answer the questions that ought to be engendered by that statement: Mein Kampf is necessary as a primary source for research for people who study Nazism and anti-Semitism because it was historically a crucial and widely-read text for followers of Hitler and helps to explicate the history that followed it. The truth is that Mein Kampf did perform a function historically, one that in retrospect we can recognize as necessary to the events that followed. The fact that that function was genocide on an unprecedented scale does not make it less necessary, only more horrifying.
In great part, the difficulty facing critics at this moment implicates the fraught issue of identity. As we increasingly use online aggregators, complete with ratings and mini reviews, to catalogue our likes and dislikes, we also increasingly conflate these quantified masses of data with our very identities. It's no wonder, then, that a book's necessity becomes conflated with the degree to which we agree with it. As a result, the critic risks being locked into a position that demands allegiance rather than analysis, answering a yes-or-no question instead of a why, or how. Politically speaking, this is disastrous. If a book's necessity is determined by whether or not we agree with it beforehand, then persuasion in literary form is no longer possible. A necessary book, in today's critical usage, is a sterile book, a book without the very power the critic claims for it. Before we claim that any given book is necessary, we need to confront our reasons for doing so, and if we do so, we need to say why.