Is communism necessarily or strongly predisposed to totalitarianism? Were the two previous communist governments (and many communists hold that the Soviet Union and the People's Republic of China reverted to state capitalism and the bourgeoisie of the party in the middle of the 20th century) totalitarian?
First of all, we have to be a little more precise: totalitarianism is not very well-defined. You could make the case according to Wikipedia's definition that the West, including the United States, is "totalitarian" if you consider the ruling economic class as the government. Mass propaganda? We call them "commercials". Enforcing ideological purity? "Are you now, or have you ever been, a member of the Communist Party?" Mass imprisonment? The United States has the largest prison population in the world, both in absolute terms and relative to population. Violation of ordinary civil liberties? The War on (some people using some) Drugs, endorsed and enforced by supposedly liberal Democrats as well as Republicans. Genocide, mass murder, imperialist aggression? The American Indians, the Philippines, Vietnam, Iraq.
It very much looks like "totalitarian" means "a government I don't like" in just the same sense that "judicial activism" means "a decision I don't like."
We might adopt a weaker standard, and say communist governments in the past have acted specifically in egregiously bad ways.
Are such allegations true? Perhaps, but if you're like me, you're getting all of your information about the history of communist governments from sources massively biased towards capitalism. I'm not saying that such sources are necessarily wrong, but ordinary standards of critical thought demand that you take obviously biased information with a very large grain of salt.
To what extent were egregiously bad actions explained not by communism per se, but by local historical circumstances? It's not like pre-revolutionary Russia or China were magic happy utopias; they were brutal, violent repressive dictatorships resting on de facto slavery. As an analogy, imagine if the South had won the Civil War, and a generation or two later the vastly numerically superior blacks had finally overthrown slavery in a violent revolution. Would you not imagine that — whatever their political or economic ideology — they would have extracted savage vengeance against those who had subjected them to centuries of misery and brutal exploitation? And, as much as we deplore violence, how much could you blame them?
Communists are not stupid, nor are they indifferent to human suffering. The whole point of communism is a reaction to horrors of capitalist exploitation and oppression of the working class; if capitalism worked the way capitalists themselves say it ought to work, communism would be pointless. It's easy for people in the United States to close their eyes to exploitation, because we export most of it, and we've "bought off" a fair portion of working American people. If you want to see the pointy end of American capitalist oppression you have to travel to Mexico, Guatemala, Honduras, Nicaragua; indeed most of Latin America. Or just Detroit. Live in a lily-white suburb surrounded by other members of the top economic 10%, and it's very easy to convince yourself that everyone lives the same way, just with Target and Wal-Mart crap instead of Williams-Sonoma and Sharper Image crap. Communists are just former capitalists who have rejected the dogmas of the ruling class and opened their eyes to what's really going on in the world.
The next time that someone tells you that communism is totalitarian, ask them: compared to what?