Here's something worth reflecting upon:
We take other men's knowledge and opinions upon trust; which is an idle and superficial learning. We must make them our own. We are just like a man who, needing fire, went to a neighbor’s house to fetch it, and finding a very good one there, sat down to warm himself without remembering to carry any back home. What good does it do us to have our belly full of meat if it is not digested, if it is not transformed into us, if it does not nourish and support us?
— Montaigne in The Complete Essays (“Of Pedantry”).
It's easy to take others' opinions and make them our own; they’re the ones who did all the work and presented their ideas on a particular subject. It requires very little effort on our part to agree with those opinions and make it seem like we came to that conclusion ourselves.
We don't need to read the whole report, just the executive summary. Quickly glance at a sensationalistic headline and you’ve got the full story, right? Who has time for the nuanced argument? Do the thinking for us. We only have time for conclusions, please. This is especially true in an age of abundant technology and distraction.
It's easy to skim a book to get to the point as we see it. “We skip reading the whole thing,” Seth Godin writes, “because it's easier to jump to what we assume the writer meant.”
Many great works are interpreted more than they are read in their entirety.
It's easy to gloss over the parts that contradict our opinion and read the ones that support our position or stance. See: Confirmation Bias.
We read but often we don't digest. Reading involves effort; the more you put in the more you get out.
The same applies to conversations. We are so busy thinking we understand the other person that we start thinking about what we want to say before they've even made their point. We hear them, but we're not really listening.
Being aware of this is the first step in shifting mindset towards the pursuit of true understanding. When it comes to taking the opinions of others and making them our own, we skip the thinking. We don't do the required work.
Complement with how to retain more of what you read.