"You can't do much carpentry with your bare hands and you can't do much thinking with your bare brain." -- Bo Dahlbom.
The book is by Philosopher Daniel Dennett. The book is surprisingly readable for a philosophy book, which are full of jargon and big words. Dennett took special care in writing in a simple an clean way. For this, he recruited help from undergraduate students in his university, Tufts. The book content was discussed at an undergraduate seminar Dennett offered, and he then got help from these students review the book. This is later revealed as one of Dennett's thinking tools: "Explain to nonexperts: use a decoy audience". I think that worked: the book is accessible to an undergraduate, but a motivated one.
The first chapter explained about intuition pumps and thinking tools. An intuition pump is a simple mind tool. Dennett mentions Galileo's thought experiment that concluded small and big things fall with the same speed as an intuition pump. (Galileo thought about tying a light rock to a heavy rock. If you accept the faulty premise, since the combined system is more heavy it should fall faster, but on the other hand, since the light rock is supposed to fall slower, shouldn't it be slowing down the heavy rock it is tied to. Contradiction.)
A good story/narrative, such as "Sour grapes by Aesop", qualifies as an intuition pump for thinking about some behavioral motivations. Dennett says scientists often underestimate the use of informal tools of prose & poetry as intuition pumps. But this is probably rightly so, because some intuition pumps are misleading. Dennett calls these "Boom Crutch" (he has a catchy name for everything), and uses those to replace the technical jargon.
Chapter 2 is about general thinking tools. Dennett says "History of philosophy is smart men making tempting mistakes". But he is of course not saying that as a negative. He later continues to say the following. Making mistakes is the key to making progress. In contrast to animals, humans can remember their previous thinking, and reflect on their previous thinking and learn. For writing, blurt it out, then you have something to work with. You need to make mistakes to find the right questions. Philosophy is what you do to figure out the right questions.
To give examples of thinking tools, Dennett talks about reductio ad absurdum ("argument to absurdity"). He talks about Occam's razor: "Don't add unnecessary parameters to overfit the data". He also talks about the dual of Occam's razor: Occam's broom with which one whisks away data/facts that doesn't fit the theory. This commits the omission fallacy, and is an example of a Boom crutch. He also mentions other Boom crutches, "rathering" and "surely" which are used for dictating a false dichotomy. Finally, Dennett talks about "Jumping out of the system", a.k.a. Jootsing (he has a short funny name for everything). He says that for there to be creativity, there needs to be rules to rebel to.
I stopped reading at Chapter 3: Thinking tools for meaning or context. This is a big book at 460 pages. Although it is readable, I wasn't motivated enough as the thinking tools mentioned became more specialized for philosophy. The book talks mostly about philosophers' toolkit, and these tools are not as useful for nonphilosophers.
After reading the book, I got a pretty good idea about how the philosophers work. A friend once mentioned me a quote "Philosophy is a race to see who can think the slowest". It is said in jest of course, and probably a better way of putting "slowest" is "deepest/most exhaustively".
For us the nonphilosophers, the practical minded, the question should be: what are the thinking tools that can make our lives better?
I think some thinking tools carry across domains, but most are not. That is why we specialize in domains, and learn thinking tools that apply for those domains. And often our minds are shaped for good or bad by these tools. My mind is shaped by computational thinking, a psychologists mind is shaped by behavioral thinking, etc. I was surprised the first time I saw this in action: For the same problem of making a toy car follow a circular trace, my Electronics Engineer friend had devised a differential formula and control theory solution, whereas I had an algorithmic/programmatic solution. I guess now the trending paradigm is to devise a machine learning solution. (Sapir-Whorf hypothesis anyone?)
The thinking tools may not necessarily be internal to our brains, they could be prosthetics. A simple but powerful prosthetics is writing. A good example is checklists, as Atul Gawande pointed out. As a more complicated prosthetics, Steve Jobs once called the Mac as a bicycle for the mind. A thought amplifier.
"I think one of the things that really separates us from the high primates is that we’re tool builders. I read a study that measured the efficiency of locomotion for various species on the planet. The condor used the least energy to move a kilometer. And, humans came in with a rather unimpressive showing, about a third of the way down the list. It was not too proud a showing for the crown of creation. So, that didn’t look so good. But, then somebody at Scientific American had the insight to test the efficiency of locomotion for a man on a bicycle. And, a man on a bicycle, a human on a bicycle, blew the condor away, completely off the top of the charts.
And that’s what a computer is to me. What a computer is to me is it’s the most remarkable tool that we’ve ever come up with, and it’s the equivalent of a bicycle for our minds.” -- Steve Jobs