Man is a social animal. One frequently found result in psychology is that people often look at others when they are trying to assess the validity of their positions.
For example, if you are in a room that is slowly getting hot most people will not simply open the window (or crank up the air conditioning if you are in the USA). They first look around whether others show signs that it is hot for them too, then maybe they ask others, and only if others agree they open the window. What might be mistaken for politeness is actually the need to verify their own position by looking at others.
Most of the times this process is okay or even beneficial (others might disagree regarding the room temperature), but it can also lead us astray. Sometimes one extreme minority position is the only one with the drive to convey their position and this might make them appear larger or more influential than they are. The loudmouth religious fanatic draws a lot of attention, so do religious groups in general when they plaster the inside and outside of buses with their advertisement.
Another great example is animal research. For years there were stickers on the doors of the university library “denouncing” the town Tübingen as a place where animal experimentation is conducted. The stickers look like the signs you have at the border of the town, but instead of the “University town Tübingen” it reads “Animal Experiments Town Tübingen”. Beside annoying me (it’s vandalism, after all) I have mostly ignored them. A while ago, however, someone stuck another sticker above them reading: “I am healthy thanks to animal experiments!”
And this got me thinking — which of the two positions is the minority opinion? Against animal experimentation or in favor of animal experimentation?
Hard to say — in reality both are probably the minority opinion. The vast majority is probably indecisive regarding the issue. They simply didn’t think about it, as they didn’t think about hundreds of thousands of other issues that play no active role in their lives.
Where it gets dangerous, however, is when people try to use the opinions of others to assess their own. In this case the only opinion they were confronted with was — for a long time — stickers against animal research. Because this group of enemies of animal experimentation were the only ones for a long time who had the drive to place stickers with their opinion in public places. Without the other side showing their position too, this is a dangerous situation, because the opponents of animal experimentation might feel very strongly about their position, but they might be a minority and they might not see the advantages (or be in the age group or have the illness that they could benefit from it).
So, I suppose it was high time that someone from the other side publicly showed his opinion — even if it was by the same vandalism as the opponents.