When we only had one or two TV or radio channels we sometimes watched/listened to programmes that we didn't really interest us at first. There simply wasn't anything else on. So now and again you might stumble upon something unexpectedly interesting and expand your horizons a bit. No chance of that now. We zap from channel to channel usually only giving a new programme a few seconds' chance before zapping on. Every opinion and subject is out there but most of us only check our favourite channels/sites; those that confirm our view of the world.
We generally assume that access to the net ensures free debate and strengthens democracy. Goverenments try to combat free discussion and political dissent by blocking social networks like Facebook and Twitter as well as stopping bloggers from publishing inappropriate information. However, there are cases where undemocratic governments actually embrace social networking as a means of combatting dissent.
There's a fascinating TED lecture by Evgeny Morozov (How the net aids dictatorships, don't forget to read the discussion under the film) where he claims that social tools can be used to spread disinformation and also enable authorities to gain access to vast amounts of information that would have been impossible in the past. They may even positively encourage bloggers to write on seemingly important issues in order to give the impression that there is indeed free debate in the country. This seems a much smarter policy than simply cutting access or blocking certain sites. Morozov is not denying the power of the net to strengthen democracy and education. He's just pointing out the reverse side of the coin that seldom appears in public debate.
Just as the net enables global networking and increased access to knowledge it can also lead to passivity. Only a small minority of net users are active in any significant way. One problem on the net is that you can choose what information you want to see. You read the news you want to read, visit sites whose views you agree with and seldom get confronted by opinions that challenge your own. Of course this has always been true to some extent but today you are able to filter out unwanted facts and uncomfortable opinions more effectively than ever before.
I remember before commercial radio started and those in favour of it claimed that with commercial radio we'd get a wider choice of music. Now we've got dozens of commercial channels all of which play "non-stop hits" mixed with phone-in competitions. The only channels that play new music and a wide variety of styles are the state-run channels (at least that is true here in Sweden). Without them we'd just hear the same hits round the clock.