"We often hold our views prejudicially, that is without looking at the opposing arguments, and then we react in a knee-jerk kind of way to people who differ from us." Greg Koukl
Most people will read this quote and immediately react by saying, "Yes, that is exactly what my 'opponents' do all the time! I get so sick of that!" I can only encourage you to look in the mirror. In truth, the odds are that you too react in this way (as do I). It is a reality of humanity, although people are far more willing to see it in others than in themselves.
When dealing with a "hot topic" issue, ask yourself why there are so many otherwise intelligent people on both sides? Is it possible that you really are not as well acquainted with the opposing justifications as you should be? Is it possible you are not even familiar with the purported justifications for your own position? Have you really thought those through or are you allowing yourself to be run by your emotions and your desires, simply repeating what others have said because it is what you want to believe, assuming that those "others" did their research when in reality they too are simply repeating some meme they have heard over time?
I find that ad hominem attacks are often a cover for a lack of reasons. This is a natural outgrowth of the emotional basis for our convictions. When we formulate our worldviews based upon what we want to be true, we have no answer when asked to give a rational argument. The only avenue available to us is to lash out emotionally and attack or ridicule our opponent. The reason ridicule is such an effective tool is precisely because people base their opinions on emotions. By making an emotional appeal, we strike directly at the heart of the source of our convictions.
We do not demand a rationale for opinions. We let those with whom we want to agree off the hook, allowing them to get away with simply making an assertion and assuming that an assertion is the same as an argument. We construct straw man versions of what our opponents have to say, not because we have any real desire to understand why they believe as they do, but because want to feel more secure in our convictions and are afraid of confronting anything that might challenge them. This accounts for the sad state our culture finds itself in and our inability to discuss our differences calmly and rationally. How can you discuss an issue rationally when you have no rationale?
Perhaps it is time for us all to educate ourselves more thoroughly, truly keeping an open mind, before we allow ourselves to become so emotionally invested.