Don't Live in Your head
Know thyself!

Who could possibly be against the Socratic maxim?

Well, the ever-insightful Goethe, for once.

He argued that it is only through others that we can hope to gain insight into what is going on with us, not through introspection. We are simply too messed up to be our own judge. He wrote:1
Here I confess that the great and so important sounding task: "Know thyself!" has always seemed suspicious to me, as a trick of secretly conspiring priests who wanted to confuse man by unattainable demands and to lead him from the activity towards the outside world to a false inner contemplation. Man knows himself only in so far as he knows the world, which he becomes aware of only in himself and only in it. Every new object, well looked at, opens up a new organ in us.
In other words, our first order of business is to observe the world as it really is, which in turn gives us access to new insights, new capabilities, new inner lights.

However, it is not primarily material objects we should be concerned with, but other people:
But the most supportive are our neighbors, who have the advantage to compare us with the world from their point of view and therefore to gain a closer knowledge of us than we can gain ourselves.

In mature years, I have therefore paid great attention to the extent to which others would like to recognize me, so that I could become clearer about myself and my inner being in and through them, as through so many mirrors.
The people around us serve as mirrors that we should take seriously. If done right, this is the exact opposite of narcissism: whereas the narcissist projects his own grandiose image outwards and then enjoys looking at this false projected image, Goethe looks at the real image of himself as reflected back from the truthful mirror provided by trusted friends.

This means our task is to distinguish between distorted mirrors and truthful mirrors: between those people who are honest and well-intentioned and those who are dishonest and don't want the best for us, and between our own projections (what we want to see reflected back) and truthful reflections.

Adversaries do not come into consideration, because my existence is abhorrent to them, they reject the ends according to which my actions are directed, and the means to this end they consider to be just as much a false endeavor. I therefore reject them and ignore them, because they cannot advance me, and that is what everything in life depends on; from friends, however, I let myself be as much conditioned as guided to the infinite, I always look to them with pure trust for true edification.
There's really nothing I can add to that, except pointing out that distinguishing between "adversaries" and "friends" can be very tricky indeed.