That's a tall order. I'll try:

Noticing that people who are the best in any sport practice the most and concluding that being good at a sport is simply a matter of practice and determination. Tabula Rasa in general.

The supply-demand model of minimum wage? Is this political? I'm not saying minimum wage is good or bad, just that the supply-demand model can't settle the question yet people learning about economics tend to be easily convinced by the simple explanation.

That thermodynamics proves that weight loss + maintenance is simply a matter of diet and exercise (this is more Yudkowsky's fight than mine).