@wjtk you have presented a couple of valid concerns; which bother me as well.
1. How can one be sure that there are no terrorists or people that have committed crimes against humanity amongst potential refugees? I mean European intelligence services may conducts their investigations but nothing can eliminate the risk 100%?
However, having said that, a terrorist that has been documented and fingerprinted is somewhat easier to watch than a terrorist that is physically present but not entered into any system (meaning entered illegally and never presented themselves to authorities). Yet both of these categories are easier to watch than online terrorists that recruit through the internet and brainwash young people into committing acts of terrorism. I am not saying that it is acceptable to have terrorists physically present in Europe. I am just comparing potential threat levels. Finally all threats are threats. Keep in mind, it is impossible to eliminate all threats and the best we can do is reduce them. Terrorists are not born, they are created. I am not saying that it is Europe's fault, but it is affecting Europe. I don't have a magic solution for this problem and I don't think anyone else does, other than big talk.
2. Today 1000. How we know what will the numbers be tomorrow? And would Europe opening the doors today to some encourage others to take the risky journey to Europe? Today nobody knows how many refugees the conflicts or other circumstance going on will create in the future.
What I know from having contacts in countries such as Syria is that people are only getting on these boats out of pure desperation. They are hoping that once they settle somewhere they can send for their families to join them. These people are not arbitrarily taking the risk in the search of a free lunch. Syrians that are seeking economic immigration don't come to Europe, they go to the GCC instead where they know from vast experience there is a much higher money making potential. Syrians that come to Europe are seeking security
. I cannot comment about migrants from other countries because I don't know enough about their circumstances, but I know about Syrians in particular because I volunteer with NGOs that are helping in Syria.
If the Polish gov decides to take on some refugees, I think we need to make an effort to integrate them into society, teach them Polish and get them familiarized with the Polish way of life. Otherwise they will isolate themselves in little islands and all sorts of problems can happen. On the other hand if the Polish gov decides NOT to take any, then I guess you have nothing to worry about?