The reasons — or excuses — for a pro-censorship stance are usually twofold:

• social;
• political.

Sometimes the social reasons given (i.e. child pornography or pornography in general, gambling, religion-related, public order, etc.) can be taken at face-value as the real, factual reasons behind an Internet censorship idea. This was the case several times in Poland, and probably is the case in most European censorship debates.

Sometimes, however, they are just an excuse to cover the more insidious, real political agenda (like censoring dissent speech and opposition, as in China, Iran, Korea).

The crucial issue here is that it is not easy to tell whether or not there is a political agenda underneath the social argumentation. And while it is counter-productive to assume malice and such political agenda in every case, it is also expedient to be aware of the real possibility it is there, especially when the number of different actors involved in such a debate is taken into account.

There is a number of (often important and pressing) social issues that are brought up as reasons for Internet censorship, including:

child pornography (this is by far the most potent argument used by censorship supporters, and it is bound to show up in a discussion sooner or later, even if it starts with a different topic — it is wise to be prepared for its appearance beforehand);

• pornography in general;
• gambling;
• addictions (alcohol, drugs available on the internet, allegedly also to minors);
• public order (this one is being used in China, among others);
• religion-related;
• libel laws;
• intellectual monopolies,
• local laws (like Nazi-related speech laws in Germany).

The crucial thing to remember when discussing them is that no technical solution ever directly solved a social problem, and there is no reason to believe that the technical solution of Internet censorship would solve any of the social issues above.

Censorship opponents also have to be prepared for the inevitable adding of new social excuses in the course of the debate. For example, in Poland with the Register of Illegal Sites and Services, the Internet censorship idea was floated due to anti-gambling laws and foreign gambling sites. During the course of the discussion there were other excuses used to justify it, namely child pornography and drug-related sites.

That's why it is important not only to debate the merits of the excuse, but to show that Internet censorship and surveillance is never justified, regardless of the issue it is supposedly meant to tackle.

It is worth noting, however, that such adding of additional excuses for censorship can backfire for its proponents. If the anti-censorship activists make the pro-censorship actors (i.e. by using the “slippery slope” argument) state clearly at the beginning of the discussion that such censorship shall be used for the stated purpose only, adding additional excuses for it later can be countered by a simple pointing that out and claiming that they are already slipping down this metaphorical slope even before the measures are introduced.

These are fairly straightforward. Being able to surveil and censor all Internet communications (and with each passing day the importance of Internet as a communication medium rises) is a powerful tool in the hands of politicians. It enables them to make dissent and opposition disappear, make it hard or impossible for them to communicate, easily establish the identities of oppositionists.

As Internet censorship requires deep packet inspection, once such a system is deployed, there are no technical issues stopping those in control to modify the communications in transit. That opens the door to even broader set of possibilities for a willing politician, including false flag operations, sowing dissent among the ranks of opposition, and similar actions. The Counter-arguments

There are three main groups of arguments that can be used to fight Internet censorship and surveillance ideas:

• technical and technology-based;
• economy- and cost-related;
• philosophical (including those based in human rights, freedom of speech, etc.).

At the end of this section some useful analogies are also provided.

The good news is, all things considered there are very strong anti-censorship arguments to be made in all three areas. The bad news, however, is that all three kinds need to be translated to or used in emotional arguments to sway the general public at some point.

Again, as a rule neither the general public nor the politicians and civil servants that further the pro-censorship agenda have decent understanding of issues involved. Putting the issues in easily-grasped and emotionally loaded examples or metaphors is an extremely potent tactic.

Several counter-arguments (for instance, jeopardising e-economy, or pushing the blocked content into darknets, as discussed below) are related to the Law of Unintended Consequences: the fact that we cannot ever predict all possible consequences of any action, especially intrusive actions with regard to complex systems. Introducing censorship in the Internet is just such a case. Calling upon this fact and this law can itself be a good counter-argument.

It is also well worth keeping in mind to make sure (if at all possible in a given local political situation) that the anti-censorship action cannot be manoeuvred into any particular political corner (i.e. so that it's not called “leftist issue”). Censorship and freedom of speech are issues that are of interest to people from any side of the political spectrum and being able to reach out even to groups that would not be willing to agree with you on other issues is crucial. Technical arguments

Due to the technical make-up of the Internet there are several strong technical arguments to be made against Internet censorship. The main categories these fall into are:

• it requires far-reaching infrastructural and topological changes to the network;
• it requires high-end filtering equipment that will likely not be able to handle the load anyway;
• it does not work: it is easy to circumvent, it does not block everything it is supposed to, and it blocks things that are not supposed to be blocked.

There are several ways content might be blocked/filtered on the Internet, and several levels that censorship can operate at. Each has its strong and weak points, none can guarantee 100% effectiveness, all have problems with over-blocking and under-blocking, all are costly and all require Internet surveillance.

Effectiveness of Internet censorship measures is never complete, as there are multiple ways of circumventing them (depending on the given measure).

Over-blocking occurs when a legal content that should not be blocked is accidentally blocked by a given censorship measure. Depending on the particular scheme chosen this might be a problem pronounced more or less, but it is always present and inevitable. It does not relate to situations where the block list intentionally contains certain content that should not officially be blocked.

Similarly, under-blocking is content that officially should be blocked, but accidentally isn't. It is not content accessible by circumvention, but simply content that is accessible without using any special techniques that “slipped through the fingers” of the particular censorship scheme.

Both the resources required (equipment, processing power, bandwidth) and the cost of handling the list of blocked content also vary between censorship schemes and depend on method used.

Whether or not a method employs deep packet inspection (DPI) is indicative of both how intrusive and how resource-intensive it is.