Liberum veto meant that passing any law has to be agreed upon by ALL members of the parliament (mostly nobles). This was the reason not a lot of important legislation was passed or amended (like increasing taxation to support a bigger army, granting the king more powers, or even repealing the liberum veto right). Of course some people were worried and wanted to change the state of affairs, but their plans did not succeed. Some argued that the Commonwealth was so weak, it’s neighbors did not see it as a threat and therefore had no incentive to attack. Sadly, that was not the case, as the Commonwealth was surrounded by powerful empires ruled by absolute monarchs - Prussia, Russia and Austria-Hungary, that wanted to expand their influence and territory whenever possible. Most likely the Commonwealth survived as long as it did only because the status quo between these three empires. If one of them seized a sizable portion of Poland-Lithuania, the other two would come together and declare war against it because of fears of it becoming too powerful in the region.
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