Is disagreement protected in democracy

There are two major answers.

The first is the original answer of people like john Locke. They believed that every individual started with some basic, inviolable rights that either arose from human nature itself or were given to them by God, that the rights of groups were really no more than the rights of the individuals in those groups, that groups could only have a right to control others where individuals had that right. So, if I have no individual right to force people with views different from my own to be quiet, then no group had a right to do this, even if it was one person against the entire rest of the world.

The other answer is most famously associated with John Stuart Mill and his book On Liberty. It also figures significantly in the social thought of Karl Popper and his book The Open Society and Its Enemies. It is that a society can only keep from developing the wrong ideas by allowing its ideas to be constantly challenged by an adversarial process.