Why did the Founding Fathers designate three branches of government?

Answer 1

There was a constitution before called the Articles of Confederation and it only had 1 branch. It was very weak and the states ran everything and the government did nothing. The founding fathers wanted 3 branches so just one branch couldn't control the country and the other branches could watch over other. That way the branches wouldn't be too strong or too weak.

[Improvement by Leviosa]

Actually it wasn't only the Founders who put forth the notion of "Separation of Powers" that is what the aim is for the division of the branches. The basic premise is based on the communication that went on between Montesquieu, a French philosopher and political scientist, and James Madison, who is commonly referred to as the "Father of the US Constitution." The entire idea of separating the branches is twofold.

Of the first part we look at American history; consequently, we had a bunch of quasi-leaders who had been functioning in various capacities, albeit still ruled by a monarchy. Therefore the first part was incumbent upon the American people (Colonist's at the time) and their understanding of principles of government, and forms of government. Principles of course refers to the role of government in the welfare of the citizenry, ergo, life, liberty, and the pursuit of happiness, or commonly referred to as natural rights. On the other hand the people needed to come to an understanding of which form would be best for them; they hated and loathed the monarchy (divine right of King/Queen) yet rather enjoyed the idea of participating in the process or democracy in this case a "Republication form of government."

Of the second part all of the Founders, especially Madison knew the minds of men. Knowing such and through his experience in the Virginia assembly knew that politicians were out for their's. He forbade any collusion between the branches. In fact, in the Federalist Papers (9-47) Madison, Hamilton, and John Jay argued that any such concentration would distort and therefore breed corruption amongst the other branches.

Answer 2

So that there would be more of a separation of government

And so that we would have a different government system than Great Britain (because that was the reason of the revolutionary war in the first place!)

Answer 3

because one person couldn't do all the work the they splited all the jobs up into three branches.

1. Executive
2. legislative
3. judical