I made the mistake of thinking your example was an appeal to the populas but then I read something else. It is infact, specifically,
Argumentum ad numerum.
Do the number of people backing an idea make it more or less right?
It's a good question you pose. I think it doesn't make a positon more likely to be right, but it
possibly could be so.
But it's the fact that the populas can be wrong, which makes the argument unsound.
The actual
truth value of a specific situation isn't why the argument is fallacious. That's why I said it could "possibly be so". You see, you could argue that
blacks deserve the same rights as whites, and millions would agree. In this case, you would be correct.
But it's not the numbers that allow us to deduce that it is correct.
That is, your conclusion is true but your argument is fallacious. People forget this a lot and end up commiting
argumentum ad logicam.
So, the answer is that
such an argument is fallacious always but that doesn't mean the argument doesn't have a true conclusion.
An example of an untrue and fallacious argument would this;
Let's say that everybody agreed with the nazi regime, would that then mean it was likely to be right because of those thousands of thousands who agreed with it?
What about racism? There might be hundreds of thousands of racists, but like the nazis, they are clearly wrong.
So that's why the argument is unacceptable/fallacious.
Edited by mike the wiz, : No reason given.