A logical fallacy is an argument that doesn't hold together. All of its assumptions might be true, but the conclusion doesn't actually follow from them.
"Fallacy" is used to mean a few different things, though.
Formal fallacies happen when you try to prove something with a logical argument, but the structure of your argument is broken. For instance, "All weasels are furry; Spot is furry; therefore Spot is a weasel." Any argument of this "shape" will have the same problem — regardless of whether it's about weasels, politics, or J... (read more)