In Genetics and Reductionism, by Sahotra Sarkar, page 4, he considers what it means for a feature of a person to be genetic. He says that although many people assume it's simple and they understand it, actually it's a tricky problem and presents several unsatisfactory answers and explains their flaws. He doesn't offer the correct answer.

Here's the answer: A feature is genetic if the knowledge for the feature is the person's genes.

This is an example of the general purpose value of epistemology: epistemolgy is needed for solving problems in many other fields.

Let's consider an example. Jack is born and grows up to be a seven foot tall basketball superstar. Is his height genetic? Is his basketball playing genetic?

On both of these questions, some would get confused. They would say the basketball playing is a caused by a "gene-meme interaction" (or "gene-environment interaction"). That is true. Basketball coaches, and parents, are more encouraging to tall children. His cultural environment responds to tallness. And although many would overlook it, becoming tall is not purely genetic but requires environmental help, for example Jack must be fed regularly. The genes alone cannot make Jack tall without the meals.

Some would therefore conclude that both height and basketball skill, and pretty much everything else, are partially genetic.

But let's look at the knowledge. There is no knowledge about basketball in the genes. There is only knowledge about it in coaches, parents, other kids ... in Jack's culture. So basketball playing is not genetic, full stop. Note that this conclusion matches common sense, and also that it can give meaningful answers instead of just vaguely saying everything has multiple causes.

As to height, his parents don't know anything about making Jack tall[1], but his genes do have knowledge about how to construct a tall person. So height is genetic. Again the knowledge-based definition gets the common sense answer.

[1] There are some humans ideas about making people tall. You can stretch them. You can feed them "health food". You can bless them. To the extent the parents do those things — and they work — then the height is partially caused by knowledge in the parents.

Science and Human Values by Jacob Bronowski, pp 60-61

I once told an audience of school-children that the world would never change if they did not contradict their elders. I was chagrined to find next morning that this axiom outraged their parents.

What is wrong with those parents, and how can they be saved from destroying their children's minds?

Science and Human Values by J Bronowski, p 27

there exists a single creative activity, which is displayed alike in the arts and in the sciences. It is wrong to think of science as a mechanical record of facts, and it is wrong to think of the arts as remote and private fancies. What makes each human, what makes them universal, is the stamp of the creative mind.

An Introduction To The Thought Of Karl Popper, p 151, by Roberta Corvi quotes Popper:

the task of the professional philosopher is critically to investigate the things that so many others accept as evident. In fact, quite a lot of such opinions are mere prejudices, uncritically accepted as evident by very often simply false. And to get away from them, perhaps something like a professional philosopher is required, who will take his time to reflect on them critically.

which is from pages 8-9 of Offene Gesellschaft, offenes Universum, Franz Deuticke, Vienna, 1982

So whenever someone says an idea is too obvious for critical debate, too evident to take seriously disagreement about it, too well established to doubt ... well, that's silly. As Popper points out, people take for granted many false ideas, so the fact that it seems really obvious to you is no guide to its truth.

Here is (my summary, my words) the most important idea contributed to Popper's philosophy of science by someone other than Popper. It was contributed by David Deutsch in his book The Fabric of Reality:

Most ideas are criticized and rejected for being bad explanations. This is true even in science where they could be tested. Even most proposed scientific ideas are rejected, without testing, for being bad explanations.

Although tests are valuable, Popper's over-emphasis on testing mischaracterizes science and sets it further apart from philosophy than need be. In both science and abstract philosophy, most criticism revolves around good and bad explanations. It's largely the same epistemology. The possibility of empirical testing in science is a nice bonus, not a necessary part of creating knowledge.

In his book, David Deutsch gives this example: Consider the theory that eating grass cures colds. He says we can reject this theory without testing it.

He's right, isn't he? Should we hire a bunch of sick college students to eat grass? That would be silly. There is no explanation of how grass cures colds, so nothing worth testing. (Non-explanation is a common type of bad explanation!)

Narrow focus on testing -- especially as a substitute for support/justification -- is one of the major ways of misunderstanding Popperian philosophy. Deutsch's improvement shows how its importance is overrated and, besides being true, is better in keeping with the fallibilist spirit of Popper's thought (we don't need something "harder" or "more sciency" or whatever than critical argument!).

Emphasis on explanations is a theme with Deutsch. His upcoming book, The Beginning of Infinity is subtitled "Explanations that transform the world".

Another big idea of Deutsch's is that Popperian epistemology is true for all people. It sounds obvious when stated in that form, but it becomes controversial when one mentions that children are included in "all people". I think Popper would have approved of this, but he didn't go through and explain the consequences and implications for education. Deutsch has done so in detail.

Edit:

In An Introduction To The Thought Of Karl Popper, p 41, Roberta Corvi summarizes Popper, "The practical problem of induction is thereby solved: it is transformed into the problem of testing a theory". This is just the kind of empiricist mistake which Deutsch has improved on. Empirical approaches are insufficient in general because they cannot address philosophy (and epistemology should apply to all knowledge), but even in science when testing is possible, strong empiricism (i.e. we learn primarily using observation) is still a mistake.

Here are some comments on essays from the two volume book Critical Rationalism: Essays for Joseph Agassi

Paul Feyerabend / Universals as Tyrants and Mediators

No strong thesis. (No point.)

Ben-Ami Scharfstein / Our Difficulties in Finding the Right Words

Thesis is that Popper was wrong in "The Myth of the Framework". But he doesn't mention Popper or seem aware of Popper's arguments. He just says stuff Popper already refuted. Also I easily thought a bunch of severe criticisms while reading it. Also it was offensive because it said that blind or deaf people don't think like full human beings.

Also it's careless, e.g. it says "What the adult finds so difficult, the young child finds impossible." But a young child can do it, at the very least, by the method of growing up to be an adult then doing it. So it's not impossible for him. Truth is hard to come by so we have to be more careful than that.

Abner Shimony / The Confrontation and Monadology

Very short dialogs with lots of metaphorical and poetic type language and no clear arguments. Philosophy needs to make clear, understandable statements to be any good.

John Watkins / Epiphenomenalism and Human Reason

No strong thesis or conclusion. Has textual analysis about what specific people thought and meant to say (who cares?). Also contains a list of 5 arguments for pessimism and point by point optimistic commentary which is OK.

Hans Albert / Religion, Science, and the Myth of the Framework

Meandering religious discussion. Concludes atheism is true for some reason (old news, isn't it?). No strong thesis.

Tom Settle / You Can't Haev Science As Your Religion!

Pleasant, conversational writing style. Anti-materialist themes. Complains that the "selfish" gene theory of Dawkins is able to explain "altruistic" behaviors of animals. Calls Dawkins' approach "an impertinent and even insulting program" over this superficial clash of words. He doesn't argue his strong, closed-minded insults made from ignorance.

Nathaniel Loar / Religion and Rational Philosophy: Coming of Age

Lots of discussion of what other people said (who cares? I wanted a thesis). But bonus points for mentioning Xenophanes. The most interesting part was some negative comments on Bartley's views: apparently he was quite religious in outlook.

David Miller / How Little Uniformity Need an Inductive Inference Presuppose

Discussing induction with formal symbols and a formal style does not suddenly make it interesting. Popper refuted it more than enough times, and this isn't even a refutation. Most of this is tedious analysis of many possible meanings of sentences inductivists have uttered. It also comes to a conclusion about how the more evidence you have, the less strong of an inductive principle is needed. This is a vaguely pro-induction conclusion which Miller follows up by insulting induction for some reason. And anyway it can't be true unless Popper was wrong about induction's non-sequitur status, e.g. this whole argument presupposes you can have positive evidence for statements which actually you can't.

Mario Bunge / The Poverty of Rational Choice Theory

This one has a clear thesis: rational choice theory is flawed. OK, cool, and I agree. But the quality of argument is poor. Example:

[Gary S. Becker] concluded [in his 1955 Ph.D. dissertation] that discrimination by whites against blacks reduces the incomes of both groups — a result that went against the conventinoal wisdom that discrimination favors the whites. Regardless of the truth value of this conclusion, it clearly refutes the "rationality" assumption. Indeed, if discrimination does go against the self-interest of the whites, why have so many of them been practicing it systematically and for so long in the USA, Africa, and elsewhere? Was it not because it is highly profitable at least in the (rather longish) short run?

Bunge says the truth value of the conclusion doesn't matter. But it does. If it's false that racial discrimination is counter-productive, then racism presents no problem to the rationality principle. It's only if Becker's conclusion is true that a bunch of white people have behaved contrary to their self-interest.

Bunge then asks why people did it. Maybe because they were racists? Maybe they didn't know it was counter-productive. Maybe they didn't think about economic efficiency when choosing the behavior. Easy question to answer, yet somehow Bunge seems to think he's scored a strong point with his rhetorical question that isn't supposed to leave Becker an answer. Finally Bunge asserts without argument (in the form of a question) that Becker was wrong. If you're going to bring up Becker's dissertation, and say it is false and actually racisim is profitable, shouldn't you mention some of Becker's arguments and criticize them?

Also, btw, Bunge's pro-racism views seem to me the kind of thing one should be a bit more catious about. Do you really want to assert racisim is beneficial without careful deliberation and argument? That's the kind of really awful, anti-liberal conclusion I'd want to be thoughtful about.

By the way this whole thing is a bit strange because Becker's conclusion that people did something that wasn't in their interest clearly contradicts the rational choice theory Bunge says he was advocating (which says people always know what's in their interest and do it).

By the way, rational choice theory, in that incarnation, is ridiculous since just plain ignores ignorance including ignorances of not-yet-invented technologies. If it was right I would have invented the iPhone before Apple since it was in my interest to do so. Except Apple would have invented the iPhone earlier too since that was in their interest. And don't forget my neighbor. This thing is quite a mess!

Noretta Koertge / A Popperian Sociology of Science: The Problem of Credit

Belives there is such thing as "epistemic weight" which is justificationist (weight = amount of justification/authority provided). Uses the common technique of discussing arguments other people wrote instead of providing a strong, original thesis. And, as is common, it picks a variety of boring and unimportant arguments to discuss, such as the feminist claim that it's undesirable for science to be objective because science should incorporate progressive political views.

It considers what it'd be like if all academic papers were published anonymously so people didn't worry about credit and fame, only content.

Lawrence A. Boland / Style Vs. Substance In Economic Metholodogy

It says:

One would think that given all the current discussion of Karl Popper's views of the philosophy of science that communication ought to be easy

But that is not what Popper said nor what his views mean. It's a lot closer to the opposite. Communication is hard, hence Popper's view that by an effort we can learn from each other. The effort is required because of the difficulty to communication (and knowledge creation generally).

Ernest Gellner / Promethus Perplexed

Perplexing mix of stuff. Boring for lack of a strong thesis (i.e. lack of a point).

Jeremy Shearmur / Philosophical Method, Modified Essentialism and the Open Society

His comments about how Aggasi's work is hard to understand due to lack of structure were interesting, and apply somewhat to Popper. He made some good points about ways thinkers can go wrong.

Gershon Weiler / Reason and Myth in Politics

Promised discussion about Israel in the introduction but then mostly talked about Plato. I was disappointed.

Jagdish Hattiangadi / The First World War and 1991

Makes the good point that "liberal nationalism" (which apparently Aggasi advocated) is a contradiction. In my words, liberalism is about cooperation and harmony and the resolution of conflicts, and nationalism sets up separate groups with separate interests and thereby irreconcilable conflicts. Hattiangadi points out a different contradiction about how liberalism allows autonomy to individuals and nationalism instead to groups.

Makes several comments about Edmumd Burke which are wrong. One fact they are incompatible with is Godwin's extreme praise for Burke. (This makes a good generic criticism of all wrong-headed attitudes towards Burke. Just ask yourself: if this was true, would Godwin have liked Burke so much?)

we have a duty towards our children: to educate them, to teach them to construct a better world. A less violent world. For the goal of civilization is precisely the elimination of violence.

In An Introduction To The Thought Of Karl Popper by Roberta Corvi which gives the cite Corriere della Sera, 16 July 1992.

Nomad by Ayaan Hirsi Ali is a good book. However this statement in her Letter to My Unborn Daughter is silly:

I will bring you up to have faith in yourself, in science and your own reason and the force of life. And I will never seek to impose my own beliefs or unbelief on you.

The things in the first sentence are Ayaan's beliefs. She says both that she will cause her daughter to have them, and that she won't.

Ayaan fully intends to design her parenting so that her daughter does grow up to have certain beliefs rather than others. She's not going to be passive about it. Somehow she's trying to limit what "beliefs" encompass even though she's well aware that some cultures have wildly different beliefs about science, faith, life and reason (explaining that is a theme of her books).

A theme of Nomad is that modern Western culture is objectively better then primitive, tribal cultures, and that relativism is a mistake. Ayaan is wise to choose to promote her belief in science to her daughter. Her statement "I will never seek to impose my own beliefs" is a thoughtless platitude of just the type her book rightly opposes.