“You can argue opinions, but you can’t argue facts.”
This may, under some limited set of circumstances, be a true statement, but it assumes that a fact is something that we would all agree on if only we were sufficiently informed.
But facts are a byproduct of context. Facts are not discrete packets of truth, sharply defined and clearly demarcated from their surroundings. And a fact which we can all agree upon is the most useless and least interesting fact of all.
Another problem is that it sets up a polarity: it implies that facts and opinions are all there is, that they are the only two states of, well, I guess I’ll call it reality. But what of perceptions? You could, I suppose, say a perception is a form of opinion — but just because I can find many people to confirm what I perceive, and once we all agree and reach a consensus, then it’s a fact, right? Well…
Lastly, the statement sounds as though facts are more important than opinions; that facts finish the argument. But all too often, they begin the argument. Facts are often the least interesting thing a person can talk or argue about.