During World War II there were four major competing political philosophies.
Germany and Italy called themselves Fascists. Russia called itself Communist. America called itself Democratic Capitalists. Japan called itself an Empire, but was clearly a Military dictatorship (the emperor was controlled by a military council and was practically a slave.)
The Fascists hated Communists. They rounded them up and sent them to concentration camps - it was just as bad as being a Jew. In fact, many of the Nazis were surprised that we did not join them and attack 'our mutual enemy', the communists. They were friendly with Japan's Military Dictatorship because they had certain idea's in common. The Communists and Democratic Capitalists disliked everyone else.
Now however, a bunch of far right nutcases who have been calling liberals communists and socialists don't like it when we call them Fascists back. So they try to re-write history and claim that Fascists were some how liberals.
They do this in large part by lying about the principals behind fascism and communism. They talk about the things they have in common, ignoring the many things that they had different. This is not that hard. It's kind of like saying that Lions and Toy Poodles are the same thing because they both have fur. Or claiming that the United States is no better than terrorists because we both kill for political reasons. This logic is incredibly stupid, because it at heart ignores both history, stated beliefs, and the clear differences between the groups. Terrorism is not defined by killing for politics, but by killing CIVILIANS for politics.
You need to go back and look at what the actual fascists said they were about and compare it with what the actual communists said they were about. You need to believe the people that claim to follow those philosophies, not people that hate them.
First and foremost, Fascism was based on superiority, where as Communism was based on equality. The communists thought everyone was the same, and should all get the same stuff. They ignored exceptional-ism, Fascism on the other hand was about arrogantly believing you were superior than others and should therefore control or eliminate them.
Yes, both economic systems claimed to be merit based, but so is capitalism. Communism embraced egalitarianism and hated private property. It embraced unions and strikes by the workers who had their labor stolen from them for no payment. The idea was that the meritorious people would do far more work than the meritorious people, but generously give them the same food and luxuries. Fascism however loved private property and thought that the meritorious people should be rewarded and the less meritorious should be treated like dogs or outright killed. It hated unions and strikes, as ways for the weak to control the meritorious.
Communists put people in work camps because they tried to get extra stuff for themselves for any reason (even if they had earned it) - or disagreed with communism. Fascist put people in work camps because they thought they were inferior - or disagreed with Fascism.
The basic philosophies of Fascism and Communism directly oppose each other. Communists believed we are all ants, while Fascism believed that they are gods and everyone ELSE is an ant. Those are very different beliefs.
Communism is nothing more than the unalloyed extreme misinterpretation of a key leftist democratic principle: "all men are created equal". Similarly, Fascism is nothing more than the unalloyed extreme misinterpretation of a key rightist capitalism principle: "The worthy should be rewarded".
Note, while the extreme misinterpretations were wrong, they are based on valid ideas. Both of these directly contradictory statements (If someone is worthy, then all can not be equal.) have value to them. They are true, even though they oppose each other.
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How can two apparently contradictory statements be true? It has to do with understanding the real meaning behind them. All men are created equal does not mean that people are equal NOW (nor is it restricted just to men - women are equal to). It means that nothing that happens at or before birth - or is mostly determined by birth - makes a man less equal. The word 'created" is the key one. You can't be born superior because of race. Similarly, the 'worthy' should be rewarded refers to what they themselves DO, not what they were born as.
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But back to the main point. Fascism is very clearly not liberalism. It is in fact the exact opposite of what liberalism is. Liberalism is based on 'all men are created equal', although we don't go to the ridiculous extreme of communism. Similarly capitalism is based on the "worthy should be rewarded", although it doesn't go to the ridiculous extreme of fascism.
Why do far right zealots claim fascists are 'liberal'? Because they can't admit that conservatives might be wrong so anyone that is wrong must be liberal.
More importantly, HOW how do far right zealots claim it is? They look at the methods of Fascism instead of the principles behind it. They see that both Fascists and Communists act with disregard for the rights of individuals and think that 'dictatorship' or 'anti-freedom' is what makes them bad.
Now, being a dictator is evil. You can tell someone's a dictator when they refuse to compromise (or arrogantly claim that compromise is when their opponent does what they tell them to). But Fascism and Communism are more than simply dictatorial governments.
The methods are not what made Communism or Fascism wrong. If you used less evil methods, they would still be wrong. For example, pre-1970 America did not round up and kill black people, we just created a huge 'separate but equal' apartheid system, using democracy not dictatorship. The Jim Crow laws were still fascist even if they flourished under a democracy instead of a dictatorship.
What makes fascism wrong is not their methods, but their ideology. Because fascism is not about the methods, but about the ideology behind the method.
It was wrong in the 1940's Germany/Italy, it was wrong in the 1950's American deep south, it's wrong today.
But back to the original point. Fascism is based on inherent superiority.. Liberalism is based on no superiority. Anyone that is a liberal can not be a fascist and anyone that is a fascist can not be a liberal. They are directly opposing viewpoints.
How do you tell if someone of the left has become too communist? They don't want to reward anyone for being superior. How do you tell if someone on the right has become to fascist? They believe someone is inferior without proving that that specific person has done something that makes them inferior.
Key examples of Fascism in the far right today are the anti-gay political agenda and the anti-minor immigrant issue. In the first case, they think gays are inferior without any logical reason (religious beliefs can not count in a country with religious freedom). In the second, they are declaring the kids inferior, wrong, and attempting to punish and blame them for crimes their parents committed.