They thought the power of the Government could limited by dividing the power between different branches and levels of government. The Constitution is based on the separation of powers and a system of checks and balances. The founders felt that by dividing the power between three branches the power of government could be limited.
They were following the advice of Baron Montiesque that power corrupts and absolute power corrupts absolutely. The philosophy was that people want to do good but are easily corrupted doing what is bad. Therefore people have to be protected from the power of the government.
The bill of rights the first 10 amendments to the constitution were also designed to limit the power of the government and protect the people from the power of the government.
The second amendment allows the people to have weapons so that the people can over throw the government. The tenth amendment is suppose to limit the power of federal government. Any powers that are not specifically given to the federal government are reserved for the state governments and the individual people.
