Picture some serious non-fiction tomes. The Selfish Gene; Thinking, Fast and Slow; Guns, Germs, and Steel; etc. Have you ever had a book like this—one you’d read—come up in conversation, only to discover that you’d absorbed what amounts to a few sentences? I’ll be honest: it happens to me regularly. Often things go well at first. I’ll feel I can sketch the basic claims, paint the surface; but when someone asks a basic probing question, the edifice instantly collapses. Sometimes it’s a memory issue: I simply can’t recall the relevant details. But just as often, as I grasp about, I’ll realize I had never really understood the idea in question, though I’d certainly thought I understood when I read the book. Indeed, I’ll realize that I had barely noticed how little I’d absorbed until that very moment.
…All this suggests a peculiar conclusion: as a medium, books are surprisingly bad at conveying knowledge, and readers mostly don’t realize it.
I think that there are two groups to blame: readers and writers.
As Matuschak points out, readers do not read actively enough. I have pointed out that I read a nonfiction book with an eye toward reviewing it. As I read, I am thinking in terms of summarizing each idea in my own words and of coming up with a critique.
Book authors pad too much. Sometimes, I will finish writing a book review and say to myself, “If people read this review, they don’t have to read the book.”
In my opinion, the educational return on investment for the consumer is highest on essays and blog posts. Books are next.
Podcasts are difficult to compare with written materials. One of their advantages is that you can listen while doing something that keeps you from reading, which means that the opportunity cost can be low. Another advantage is that sometimes a conversation is more stimulating than a monologue. But when you could be reading, that is more likely to be educational than listening to a podcast.
One thing about books is that a lot of effort goes into them. Authors spend time working on them. Editors spend time screening them. Editors and others spend time making suggestions about them.
Another thing about books is that they are focal. People can use heuristics like “What are the best-selling books”? or “Who are the authors I’ve heard of?” But even if you do that, before you read the book you should search for an essay by the author that is based on or is the basis for the book.
My guess is that writers could contribute more at the margin by blogging than by composing books. But perhaps blogging is a more difficult skill.