Capitalism, Socialism, and Communism have been discussed quite a bit lately. Some have even suggested Capitalism doesn't work and we need more of a mix of Capitalism with Socialism or Communism. However, there is a great difference between the underlying principles of each system that are important to understand before one decides to start calling for more Socialism or Communism. Although many people don't understand it, the fundamental principle of Capitalism is property rights and thus by extension, individual freedom. Capitalism simply means you have the ability to keep your own property, which then gives you the freedom to choose how you use your own property. (Property is anything you own, like money, land, your home, your car, etc). Laws of the State would still apply in cases where your use of property infringes on the rights of others. Capitalism is not anarchy; it simply means people are free to choose.
Socialism and Communism, on the other hand, are based on the principle that an individual ultimately does not have property rights, at least not above a certain level of possessions. Socialism and Communism are often justified because of its humane and equal treatment of the working class. However, that equal treatment is only accomplished through seizer of another's property. Once the people "own" all property (most commonly the means of production) someone has to run it. Who else runs what the people own than the people in charge? Although the people "own" it, its use is actually determined by those in power. Those in power thus "represent" the people, but usually end up owning all the property, not the people.
Socialism and Communism are not inherently evil as many people are led to believe. In fact, either one could work quite well among people who willfully choose it. The question is who will choose it willfully? Those who have much personal property usually don't want it, but those who have much to gain usually do. How do those without gain something under Socialism or Communism? By forcing those with property to give it up against their will. This is the problem with these as systems of government - they basically represent the forced confiscation of personal property against an individuals wishes.
When everyone is forced to live under Socialism and Communism you remove their right to own and control their own property, and thus you remove their individual freedom. If the collective wants what you have they take it, whether you like it or not. You have no legal means to stop the confiscation of your property; thus you have no freedom. You cannot have freedom without property rights, and so by basic principle Socialism and Communism remove a measure of your individual freedom.
As for why not have a mixture of Capitalism and Socialism or Communism, we already have such a mix today in the US. As long as a majority will support and vote for representatives who will raise taxes on the minority (rich people), this is allowed in the US. A truly Capitalist society based on individual property rights wouldn't allow such unequal confiscation of property (unequal meaning taking more from one person than the other, or taking a greater percentage of tax from one than the other).
The Constitution gave Congress power to level "uniform" taxes, but since the 16th amendment allowed income taxes the idea of taxing a minority for the benefit of the majority has gained much popularity. Today we certainly have property rights and freedom, but they are curbed to a certain percentage (based on tax rates) depending on your yearly income. For example, some high income earners in high tax States end up paying over 50% of their yearly income to various Federal, State, and Local taxes. So the question today is not why not have a mixture of Capitalism and Socialism or Communism, but a question of whether we should have more Socialism/Communism and less Capitalism.
We really need to ask ourselves, 'Do we want more individual freedom, or do we really want more government control over our lives?'