assistant: Political power, as a general rule, is something that humans want to have. This is because no matter what a human cares about, it will almost always be easier to achieve with more political power. At the same time political power is scarce: if one person gets to decide something that means another person does not get to decide the same thing. This naturally puts humans in a competition over political power, colloquially often referred to as a power struggle.

Now consider how political power is used. In more primitive times maybe the leader, who was the biggest and strongest, was able to coerce the rest of the group into doing what they want, but this is no longer the case. In the modern world leaders cannot directly make others do what they want through their own strength - they are using the strength of the political system instead. For example, a lawmaker cannot possibly go around in person to stop millions of people from doing things they don't like but they can instead pass a law that prohibits the thing that they don't want others to do. But why does the lawmaker in this example get to make this decision in the first place? The answer is that the rules of the political system say that he does.

Things are now coming together: humans want political power and in the modern world political power is determined by the rules of the political system. Therefore humans will want to change the rules of the political system in their favor to increase their own political power. And the ones that are the most able to do this are the ones that already have a lot of political power in the first place. This can lead to a situation in which a single person becomes the one that gets to decide everything. In fact, throughout human history this arrangement was the predominant way in which societies were organized. In the past there were many different names for the one that got to decide - king, emperor, etc. - but nowadays you would call them a dictator.

Now, while it is theoretically possible for a dictator to be a benevolent person that upholds human rights and treats others with respect the sad reality is that this is exceedingly unlikely. Many of the most effective ways for humans to gain political power are highly unethical. Therefore the people who rise to the top are likely to be the ones that have no problem with for example incarcerating or killing the people who oppose them. Modern democracies aim to prevent unethical people from abusing their power for their own gain via what is called a separation of powers: a single person or group of people cannot legally gain enough power to single-handedly dominate the entire political system.

The most common way that political power is separated is to divide government into branches: a legislative branch that makes laws, an executive branch that enforces the law and does the actual decision-making, and a judicial branch that decides how laws are to be interpreted. Another common way is to have a federalized system in which a central government is opposed by many regional governments. The crucial feature is that the people wielding power cannot unilaterally make decisions to increase their own political power since this would be at the detriment of the other participants who will naturally not agree to have their own political power reduced.

As a final note, let us consider an example in which there was no separation of powers: Adolf Hitler, a notorious dictator, did not come into power through violent means but was instead democratically elected by the German people. However, once Hitler was in power he used his position to legally become both chancellor and president at the same time which granted him immense political power. Eventually a law was passed that granted him even the power to arbitrarily pass laws at his own volition and at that point he had essentially established himself as a permanent dictator. If it had been illegal to become both chancellor and president at the same time or if the constitution had prohibited to grant legislative power to the chancellor (the head of the executive branch), then Hitler may have never been able to become a dictator and history would have been very different. It is often said that those that do not learn from history are doomed to repeat it, so in conclusion the importance of a separation of powers is to prevent the rise of dictatorships or oligarchies.

prompter: Can you provide MLA formatted sources for this information?

assistant: The importance of the separation of powers in a political system can be observed in how well implementations of Trias politica function.
in Trias politica which is the most well successful implementation of separation of powers. you notice that the powers keep each other in check. With Police, Judge and Politicians being the three powers.
This will not prevent bad descisions but more likely will prevent extremely bad decisions and extremely good decisions. and will keep decisions more moderate. 
Mustafa Kemal Atatürk was a well known dictator that implemented some great ideas while Adolf Hitler implemented some horrible ones.
If powers are separated you will have less extreme cases that is the Importance of separation of powers