After reading “Knowledge”, I feel like this runs counter to a lot of the themes I’m trying to follow like the ones found in “Essentialism.” This book explains epistemology which is the philosophy behind what we know, how we know it, and how that relates to everything around us. I like the distinction the author makes between “I know” and “I think” because we oftentimes treat those terms as synonymous. Ultimately, if I really delved into many of the subjects found in this book, I would be using a lot of my mental resources and time to try to answer questions that really don’t hold up to the question “Is this useful?”

1. The hunt for knowledge has never been easier. Hard questions can be answered with a few keystrokes. Our individual powers of memory, perception, and reasoning can be double-checked by distant friends and experts, with minimal effort. Past generations would marvel at the number of books within our reach. These new advantages don’t always protect us from an old problem: if knowledge is easy to get, so is mere opinion, and it can be hard to spot the difference.
2. What is the difference between just thinking that something is true and actually knowing that it is?
3. Like many resources, knowledge can be acquired, used for diverse purposes, and lost—sometimes at great expense. But knowledge has a closer connection to us than resources like gold and water. Gold would continue to exist even if sentient life were wiped out in a catastrophe; the continued existence of knowledge, on the other hand, depends on the existence of someone who knows.
4. Knowledge demands some kind of access to a fact on the part of some living subject.
5. The Cynical Theory: whether someone’s idea counts as knowledge or mere opinion would be determined by his status as a leader or a loser, and not by anything in the idea itself or its relation to reality.
6. Human languages have remarkable diversity. But despite this diversity, a few terms appear in all known languages, perhaps because their meanings are crucial to the way language works, or because they express some vital aspect of human experience. These universals include ‘because’, ‘if’, ‘good’, ‘bad’, ‘live’, ‘die’… and ‘know’.
7. Knowledge links a subject to a truth. This feature of ‘knowing that’ is called factivity: we can know only facts, or true propositions.
8. The Ancient Greek philosopher Protagoras (5^th century BCE) held that knowledge is always of the true, but also that different things could be true for different people.
9. Protagoras says something more radical: it is true for me that the wind really is cold and true for you that the wind is warm. In fact, Protagoras always understands truth as relative to a subject: some things are true-for-you; other things are true-for-your-best-friend or true-for-your-worst-enemy, but nothing is simply true.
10. Relative truth has had more sophisticated defenders since Protagoras, but most philosophers have favoured objective truth. What is true is true for all of us, full stop, whither or not we are aware of it.
11. Ancient Greece was in fact the birthplace of two distinct skeptical traditions, the Academic and the Pyrrhonian. Academic skeptics argued for the conclusion that knowledge was impossible; Pyrrhonian sceptics aimed to reach no conclusions at all, suspending judgment on all questions, even the question of the possibility of knowledge.
12. Stoic epistemology draws a distinction between impressions and judgments. The Stoics noticed that you can have an impression—say, of shimmering water on a desert road—without judging that things really are as they seem. Judgment is the acceptance (or rejection) of an impression; knowledge is wise judgment, or the acceptance of just the right impressions. In the Stoic view, people make mistakes and fall short of knowledge when they accept poor impressions.
13. Academic Sceptics were happy to agree that knowledge would consist in accepting only impressions that couldn’t be wrong, but they proceeded to argue that there simply are no such impressions.
14. Because impressions are always fallible, the Academic Sceptics argued, knowledge is impossible.
15. We can avoid being misled by our sensations if we keep in mind that they are not designed to show the true nature of things; rather, their deliverances need to be checked against and interpreted in the light of our clear and distinct ideas.
16. If what seems to be real is real enough to be a reliable source of pleasure and pain, then you can be as certain that it exists as you need to be.
17. Sometimes, feeling sure you are right accompanies actually being wrong.
18. The way you think when you understand what someone says is different from the way you think when you see something with your own eyes, and different again from the way you think when you are engaged in reasoning or puzzle solving.