Adopting others' opinions

There are some less clear-cut examples. For example, the 'smartest' [read: some combination of high-IQ, high-rationality, knowledgeable] people I know tend to identify as either libertarians or utilitarians, rather than as socialists. There are a few exceptions to this, but not many. From this, I could arguably assume that it would be correct to adopt a libertarian or utilitarian, rather than a socialist, mindset to politics without actually understanding why libertarians are libertarian.

Since political questions involve moral evaluation, you need to know not only that they are 'smart', but also that they share your ethical values. Even then, adopting others' political opinions is generally unreliable, since most people, even smart ones, are heavily biased when thinking about politics.

You don't trust a doctor because the doctor is smart, or because the doctor is a member of a smart society. You trust the doctor because there are procedures ensuring that experiments were performed to validate these claims.

I'm sure Hippocrates was well smarter than the median modern-medicine doctor, but I'd take a second-quartile modern medicine doctor over Hippocrates any day of the week.

The good parts of this article are better presented in Information Cascades, and I downvoted for the bad parts - i.e. political buffoonery and misuse of the term "groupthink".

You're actually not talking about what is called "group think", just about accepting expert opinion (whether or not there is group think in the groups of experts you mention is anther question). Anyway, your and my practice of taking the consensus of experts to be correct without understanding why they believe what they do is both rational and pragmatically necessary.

Also, at least in the States, "socialism" is not clearly defined anymore.

This may assume a degree of reliability associated with the opinions of smart people that is only very weakly justified. See for example this previous discussion here where I made a similar sort of argument to the argument made in this essay and was given a long list of examples where smart intellectuals have been essentially wrong.

As to concluding it is a good idea to be a libertarian or utilitarian because your smart friends are, here is the potential flaw: the libertarian and/or utilitarian world may be a better one for smart people and not as good for not as smart people. If you don't even know why they are libertarian, you certainly don't know enough to conclude it is not just self-interest on their part.

Reformulating a bit to make the discussion not about the actual labels:

For example, the 'smartest' [read: some combination of high-IQ, high-rationality, knowledgeable] people I know tend to identify as X, rather than as Y. There are a few exceptions to this, but not many. From this, I could arguably assume that it would be correct to adopt a X, rather than a Y mindset without actually understanding why people identify as X.

That breaks down as soon as the knowledgeable people use the same algorithm for deciding what to believe! I assume that's why you put "groupthink" in your title.

The problem arises because we don't have a habit of distinguishing

• A) "I believe X because I personally investigated the topic",

• B) "I believe X because leading experts in the field, who investigated the topic closely, believe X", and

• C) "I believe X because other smart-seeming people believe X".

(A gets the best knowledge but is not usually cost-effective, B is perfectly sensible, and C is the-blind-leading-the-blind, but is the cheapest)

(And that problem arises because everybody has an incentive to imply more knowledge than they actually have, while not being caught in outright lies, so being vague about where your knowledge comes from gets good enough results.)

Robin Hanson recently talked about the Bayesian requirement to take in to account the opinions of other Bayesians who have more information than you do. http://www.overcomingbias.com/2012/07/finding-our-beliefs.html

I completely agree with @TraderJoe that the vast majority of what we know is by accepting the word of someone else. I am a physicist, I have never measured the magnitude of the repulsion between electrons, I have never verified that there were excess electrons on two pieces of foil that repelled each other (where I viewed repulsion but had to take on faith that it was due to electrons). I have never measured time dilation, or the bend of light around a planet and seen it was consistent with special relativity. I have measured many superconducting devices and run lots of computer programs that I have written, but in no case did I "understand" all of the measuring equipment or the computer I was running on.

Talk about economies of scale, virtually EVERYTHING I know (except for some math I guess, and is that really "something?") I know because I believe somebody else who told me the answer.