Many arguments in debates are intellectually wrong or flimsy at best. This is well known and oft mentioned by pedants. In my opinion, these transparently fallacious arguments are less insidious than their emotional counterpart, "verification by bluster". With a sufficient combination of affirmation, bravado, machismo, etc., humans appear to forget about the concept of proof.
- Confidence levels may be out of proportion to the supporting data. In a card game this would be called a bluff. If anyone asks "Are you sure?", then the answer is always "100%", in a firm voice and accompanied by a steady gaze. Do it right and humans just won't bother with whether the steely assurance is grounded in reality. This is particularly important in sales or management; complete detailed honesty about actual evidence would merely demonstrate "lack of belief".
- Naive arguers sometimes act as if winning means discrediting the other side's facts. Not necessarily true. It might be enough to invent a sufficiently nasty name for a part of the opposing argument, then repeat it endlessly.
- It's similarly naive to act as if an individual data point "speaks for itself". It's a comparatively simple matter of weighting. Take the contradictory data point, juxtapose it against a supportive data point, state assertively that you're providing "full context". Humans are unlikely to request entire data sets in any case, because analysis might involve, y'know, math.
- In general, complexity is a bad tack. Messy corner cases and ambiguous conclusions aren't gratifying. Exceptions to beloved rules are downright unsettling to some personality types. Hence the more profitable route of argumentation is to accept simplistic thinking, not challenge it. It won't work to spout admonitions to replace laughably course-grained prejudices with complicated observations. Confronted with the world as it is, right now, humans instead prefer a personalized/sanitized perspective in which solutions are easy, relationships are causal, and heroes and villains are well-defined.