The first and most important principle is that we cannot and should not draw a line between state censorship and private or civilian censorship.
[Rather] the majority of censorship is self-censorship, but the majority of self-censorship is intentionally cultivated by an outside power.
Why? (A) preventing someone from writing/saying/releasing something in the first place is the only way to 100% wipe out its presence, and (B) encouraging self-censorship is, dollar for dollar and man-hour for man-hour, much cheaper and more impactful than anything else a censorious regime can do.
Think about how many man-hours it takes to search thousands of homes one-by-one to confiscate and destroy a particular book, versus how cheap and easy it is to have a showy book burning or well-publicized arrest of an author which scares thousands of families into destroying the book if they have it. Will the show trial or book burning scare people into destroying every copy? No, a few will keep it, [but that is vanishingly small number overall.]
A great question to get at this is: Did the trial of Galileo succeed or fail?
If we believe that the purpose of the Inquisition trying Galileo was to silence Galileo, it absolutely failed, it made him much, much more famous, and they knew it would. If you want to silence Galileo in 1600 you don’t need a trial, you just hire an assassin and you kill him; this is Renaissance Italy, the Church does this all the time. The purpose of the Galileo trial was to scare Descartes into retracting his then-about-to-be-published synthesis, which — on hearing about the trial — he took back from the publisher and revised to be much more orthodox. Descartes and thousands of other major thinkers of the time wrote differently, spoke differently, chose different projects, and passed different ideas on to the next century because they self-censored after the Galileo trial — an event whose burden in money and manpower for the Inquisition was minute compared to how hard it would have been for them to get at all those scientists. The final form of Descartes’ published synthesis was self-censorship — self-censorship very deliberately cultivated by an outside power.
The structures that cultivate self-censorship also cause what we might call middleman censorship, when one actor (organization or person) is pressured into censoring someone else’s work, but via the same structures (fear, self-preservation) that cause self-censorship. The publisher who pulls a controversial title, the screenwriter who removes some F-bombs or queer content from a colleague’s first-draft script, the arts organization which refuses to screen a politically provocative film, or the school librarian who makes use of Scholastic’s infamous option to “opt out of diverse books” at a school book fair, these people are not censoring their own creations, but their complicity in censorship is often motivated by the same structures of fear and power which censorship regimes use to cultivate self-censorship.
Why would such an organization waste hundreds of man-hours per copy on crossing out pages when they could have trivially burned the book and moved on?
It was a projection of power, something to make authors and printers think “I don’t want my book to go through that.” This also made use of middleman censorship: one could apply to the Inquisition for an official license granting permission to own restricted books, but one of the conditions of this seeming-privilege was that you yourself had to go through and cross out the sentences they banned. This made the very people who loved and wanted to read restricted books into middleman censors excising text from their own copies, and experiencing the same mortifying and emotionally manipulative reinforcement a child does when forced to write a motto on a blackboard. It was a didactic tool designed to be a constant reminder of the authority’s presence
This illusion of infinite resources itself is one of the goals of such regimes, making people more afraid, and less willing to defy. It is about projecting power, and we must not fall for it as we evaluate the actions of such regimes asking “Why did they do A not B?”
ensorship systems want to be visible. They don’t tend to invisibly and perniciously hide their traces, they tend to advertise it: in big printed letters, blacked-out passages, or a brightly-colored screen. Even when a blocked website redirects you to ERROR: THIS WEBSITE IS BLOCKED, that is a deliberate choice, because that causes the most self-censorship ripple impact.