Notes on 《How the Mind Works》Ch.5 —— Good Ideas

This chapter is about human reasoning: how people make sense of their world. Steven tries to elaborate it in 4 steps.

Step 1: Distinguish people's intuitive science and academic science

Why people don't really work like scientists:

• Natural selection shaped us to master the local environment not to earn good grades in science class, and that led to discrepancies between how we naturally think and what is demanded in the academy.
• The cost of science is expensive: In a large society with writing and institutionalized science, the cost of an exponential number of tests is repaid by the benefit of the resulting laws to a large number of people.But for the provincial interests of a single individual or even a small band, good science isn't worth the trouble.
• Our brains were shaped for fitness, not for truth. Conflicts of interest are inherent to the human condition, and we are apt to want our version of the truth, rather than the truth itself, to prevail.

Step 2: Explore how our intuitions work

People form concepts that find the clumps in the correlational texture of the world.

• Why people has the urge to classify?
• Not because the mind need to reduce the memory load.
• Not because the brain is compelled to organize.
• It is because the mind has to get inference out of forming categories.
• People form two kinds of categories:
• Fuzzy categories: come from examining objects and uninsightfully recording the correlations among their features. Their predictive power comes from similarity.
• Crisp categories: work by ferreting out the laws that put the clusters there. They fall out of the intuitive theories that capture people's best guess about what makes the world tick. Their predictive power comes from deduction.

People have several ways of knowing, or intuitive theories, adapted to the major kinds of entities in human experience: objects, animate things, natural kinds, artifacts, minds, and the social bonds and forces.

People wield inferential tools like the elements of logic, arithmetic, and probability.

Logic:

• Logic refers to inferring the truth of one statement from the truth of other statements based only on their form, not their content.
• The mind seems to have a cheater-detector with a logic of its own. When standard logic and cheater-detector logic coincide, people act like logicians; when they part company, people still look for cheaters.
• The mind does seem to use logical rules, but they are recruited by the processes of language understanding, mixed with world knowledge, and supplemented or superseded by special inference rules appropriate to the content.

Mathematical:

• Mathematics is part of our birthright.
• natural selection gave children some basic mathematical abilities: determining the quantity of small sets, understanding relations like "more than" and "less than" and the ordering of small numbers, adding and subtracting small sets, and using number words for simple counting, measurement, and arithmetic.
• Formal mathematics is an extension of our mathematical intuitions:
• Counting —>arithmetic and number theory
• Measuring —> real numbers, calculus, analysis
• Shaping —> geometry, topology
• Forming —> symmetry, group theory
• Estimating —> probability, measure theory, statistics
• Moving —> mechanics, calculus, dynamics
• Calculating —> algebra, numerical analysis
• Proving —> logic
• Puzzling —» combinatorics, number theory
• Grouping —> set theory, combinatorics
• 2 ways used that people can use their Stone Age minds to wield high-tech mathematical instruments and get to mathematical competence:
1. to set mental modules to work on objects other than the ones they were designed for.
2. practice: Mathematical concepts come from snapping together old concepts in a useful new arrangement.

Probability:

• The mind is not designed to grasp the laws of probability, even though the laws rule the universe.
• The brain can process limited amounts of information, so instead of computing theorems it uses crude rules of thumb.
• the more memorable an event, the more likely it is to happen.
• the more an individual resembles a stereotype, the more likely he is to belong to that category.
• "Probability" has many meanings.
• relative frequency in the long run.
• subjective confidence about the outcome of a single event.
• Our ancestors' usable probabilities must have come from their own experience, and that means they were frequencies.
• When probablity is presented in terms of frequencies not in terms of single-event, people are more accurate.

Step 3: Where our intuitions come from

• The mind couches abstract concepts in concrete terms. It is not only words that are borrowed for metaphors, but entire grammatical constructions.
• Two fundamental metaphors in language: space and force
• Parts of our mental equipment for time, animate beings, minds, and social relations were copied and modified in the course of our evolution from the module for intuitive physics that we partly share with chimpanzees.
• Metaphors can be built out of metaphors, and we continue to borrow from concrete thoughts when we stretch our ideas and words to encompass new domains.

Step 4: How intuitions are elaborated and polished to give the virtuoso performances of modern civilization

How is the human mind adapted to think about abstract entities?

• We have inherited a pad of forms that capture the key features of encounters among objects and forces, and the features of other consequential themes of the human condition such as fighting, food, and health.
• By erasing the contents and filling in the blanks with new symbols, we can adapt our inherited forms to more abstruse domains.
• Some of these revisions may have taken place in our evolution, giving us basic mental categories like ownership, time, and will out of forms originally designed for intuitive physics.
• Other revisions take place as we live our lives and grapple with new realms of knowledge.

Because human thoughts are combinatorial (simple parts combine) and recursive (parts can be embedded within parts), breathtaking expanses of knowledge can be explored with a finite inventory of mental tools.

Geniuses are wonks(Similar to Malcolm Gladwell's 10000 hours theory for success):

• The typical genius pays dues for at least ten years before contributing anything of lasting value.
• The epiphany is not a masterstroke but a tweaking of an earlier attempt.