Taking the good of other people or the good of the group as a whole into consideration is a positive thing in order to help a democracy function. If each citizen in a democracy votes only for his or her own interests, and did not take into consideration what vote would most benefit the group as a whole, then nothing would ever get done because desires would be too spread apart. In this scenario, it would seem that interest groups or factions would be beneficial to society. Second, let us consider the cons of having such factions. When people are caught up in an interest group, they tend to only consider what their group wants. People may fail to take their own individual needs into consideration, or, more likely, they may fail to consider what is beneficial for the whole, organic society.

However, the true consideration is whether or not democracy can exist without such interest groups or factions. I believe the answer is that a democracy will inevitably have factions, therefore it is irrelevant whether or not these factions are a good thing or a bad thing. There are only so many possible interests that people in a given society will hold, and aside from the few extremists...

The majority of people will have the same basic needs. Furthermore, this is complicated by the fact that no culture is compromised of only one group of people. Regardless of how unicultural, as opposed to multicultural, a society may be, divisions such as men and women, young and old, intellectual and physical talents, and - unless it is a communistic society - poor and wealthy. Something different will be in the best interest of the young than the old, for the men than the women, and so on.
A democracy functions by each person voting for what is best for themselves or what they think is best for society, and even then what someone believes is best for society tends to be based on what someone thinks it best for him or herself. Therefore, even if no one calls a fraction of the society an "interest group" or a "faction," humans will automatically break down into groups that think the same way. The basic reasoning behind democracy is that people are rational, and any rational person will notice that their interests match up with the interests of other people. Reasonably, upon