Having spent many a column espousing the wonders of the internet, my final column will sound a warning on the dangers.

The first is anonymity. This can be a curse and a blessing online. Sites such as Wikileaks – which desperately needs funding to stay open – provide a valuable place where information can be put into the public domain anonymously.

But there is a flip side. Glance at the comments below any newspaper opinion article and you will be given a whirlwind tour of the most unpleasant aspects of the public psyche.

You don’t overhear conversations such as this in the pub or at work. It’s the anonymity that provides people with the cover to get away with such language without being hit in the face.

And it’s the anonymity the internet provides that allows authoritarian regimes to spy on businesses without the state being held responsible.

It allows criminals to perpetrate scams online that cost the public billions of pounds a year, and illegal downloaders to ply their craft without fear of apprehension.

One of the original, long-abandoned arguments for ID cards was that they could provide a person with a secure online identity, so when you logged on to your bank’s web site, for example, you could prove your identity. If people were more accountable for their online interactions, they might be more civil – and law abiding.

But the internet carries an arguably more pervasive and long-term danger than the provision of anonymity and that is the way that it changes and shapes thinking and the way people interact with information.

The online forum edge.org recently tackled this problem. It asked leading scientists, technologists and thinkers: How is the internet changing the way you think? A number of people, including American writer Nicholas Carr and science historian George Dyson, outlined fears that the web is at risk of reducing serious thought rather than promoting it.

One argument posits that a more democratic approach – with everything posted online attributed an equal weight, whether right or wrong – encourages a cavalier attitude to the truth.

Another is that collecting information online reduces our attention span. We will scan a Wikipedia article on a subject, rather than read a book about it.

Furthermore, it is harder to distinguish between the relative value of sources online. Whereas in real life we would trust a professor more than a eight-year-old, online those boundaries are blurred by a lack of clear distinction between sources – both people would be able to type a comment on a site, and we have no way of knowing who they are, other than their words.

The “trust distinguishers” we use in the physical world are easier to fake online. Whereas a professor offline could be examined for reliability by his age, manner of speaking and so on, these things are easier to disguise on the web.

In many ways the internet represents many of the same problems as a democracy. By giving an equal voice to all, it empowers many of those who are disenfranchised economically or socially and who would not otherwise be heard.

But at the same time, it gives an equal voice to the extremities of society – making it easier for those who run extremist jihadi sites, or sites that deny the holocaust, to spread information.

Just as in real life, nobody should be denied freedom of speech online. The internet can and must be accessible to everyone. But we need to develop and teach new ways in which to distinguish between, and prioritise, information that we find online if we are to retain our notions of what is correct and incorrect.