MUNICH — It only takes two minutes to gather enough material to make a person squirm or provoke them to pick up the phone to call a lawyer. Two minutes to see that racism flourishes not only on the fringes but also in the heart of our societies, in the minds of philosophy students and doctors.

A quick scroll through the comments on many newspapers’ Facebook pages before they’ve been moderated reveals racist messages posted on almost every article about the Lampedusa disaster and the more than 200 people who died.

All you need is a Facebook name and a few minutes on a search engine and you can often find someone’s address, telephone number, level of education, membership of various clubs, dates for presentations and much more. It’s not difficult to refine your search. There are websites that specialize in searching social networks, while Facebook and Twitter themselves offer tools that allow users to apply highly specific information filters.

It’s a paradoxical phenomenon. On the one hand, users make their profile settings as private as possible so that no strangers can see what they do and like. On the other hand, these same users post inflammatory comments on the Internet that are available for virtually all to see.

For example, there is the doctor who objects to refugees because he thinks they are all Islamists who oppress women. Or the atheist who posts a rigorous and thoughtful discussion about whether the state must remain strictly secular. But when he writes about the refugees killed in the Lampedusa disaster, his primary concern is that the political left will exploit the tragedy for its own ends.

There is also the former philosophy student — now a teacher — who writes texts and gives detailed presentations about racism. He often meets and helps migrants in his daily life. But on Facebook he writes that refugees are potential enemies of the state who may find it difficult to adjust to German culture and sooner or later express their grievances through violence.

In your permanent file

These examples are just a taste of the wide range of prejudiced or unsavory comments on the Internet. They are the kind of statements that are sometimes uttered over dinner or at the pub. But many people don’t seem to consider the fact that the virtual world retains permanent traces of these comments and doesn’t differentiate as to whether the writers have thought long and hard about the subject or simply poured their rage out over the keyboard. On Facebook a person’s comments are forever linked to their name.

The way Facebook is set up gives many users the impression that they are not being watched. The profile page is a clearly defined space where each user can decide how much he or she wants to give away. Comments are only partly public: Although other people can read them, they are not collected together and are soon enough lost in the sea of content.

In 2012, however, it became clear what happens when the profile page set-up is altered. Facebook introduced the new timeline function, which allowed users to scroll down and view historical comments and actions as well as the exact date when they were posted, right back to the moment when the account was set up.

Shortly after this change, Facebook users suddenly began complaining that their private messages were being published on their timelines. There was no proof, however, and Facebook strongly denied the claims. It is far more likely that users had simply changed their social networking habits and that before the introduction of the timeline they had interacted more openly and freely. “Impression management” — i.e., can my boss see the pictures from that weekend party? — was not yet a concern.

Facebook is continuing to refine its search function with the “graph search.” In the future it will be possible to generate more exact results and search through comments to see what friends are saying. This means that all comments will be collected and ordered.

For the moment, Facebook comments remain a jumble. But never forget that they are visible.