For no particular reason I just want to clarify a confusion that I have encountered fairly often, that's what the difference is between Socialism and Social Democracy. Socialism aims to achieve a more just society by putting the means of production in the hands of the government, it is against privatization (though not necessarily for common ownership, that's communism). That has a priori nothing to do with planned economy in case you wonder.
Social Democracy means you acknowledge that the free market fails to automatically take into account certain goals your society might value, that are most often those based on solidarity and long-term plans. For example environmental protection, help for medical emergencies, social help etc. An unregulated free market is merciless on the sick, the old, the poor, or the unlucky, simply everybody who fails to contribute directly to economic growth for whatever reason, e.g. by having too many kids. Social democracy includes the human wish not to see your neighbors starve the moment they can no longer be productive, and recognizes that one day you might be in that same situation.
The way it is typically done is to take away money from those who have plenty, e.g. by taxes, and give it to those who need it to survive. Yes, that means redistribution of wealth. You do that backed up by a democratic system to ensure this redistribution is considered just by the majority of people and not in conflict with more fundamental laws. Needless to say, the people who have the big money will complain about it. Keep in mind they made their money in a system that is considered unjust by the majority of people living around them. The outcome is a social market economy, that is, one that combines a capitalist mode of production with the belief that society should protect all its members from economic and social need.
Justice is however something that is perceived very different depending on what culture one has grown up in. I for example find it quite amusing that Americans like to talk about Germany as a 'social welfare' state as if that was something undesirable. As far as I am concerned, I am very relieved that if I am in Germany I know all my neighbors do have a health insurance, I know all my friends have an unemployment insurance, and I know they can live from social help should it be necessary. Of course there's parties in Germany who are more left or right leaning, more or less liberal, more or less conservative, but overall the idea of a social market economy is more generally accepted.
Choose what you want. That's what democracy is good for.