In this talk from 2010, Greg Glassman introduces the concept of “invincible ignorance” to explain why debates about training safety so often fail. He argues that the real dividing line is not between differing opinions, but between those who can articulate what evidence would change their minds and those who cannot. Claims that movements like squatting or lifting overhead are inherently dangerous persist, he suggests, not because of data, but because some critics are unwilling or unable to engage in evidence-based reasoning. Glassman contrasts this with his experience that many physicians and physical therapists, when exposed to real-world results, are actually pragmatic and persuadable. The takeaway is strategic rather than confrontational: meaningful progress comes from identifying “vincible” ignorance, reframing ideas when necessary, and focusing on helping individuals one at a time—while recognizing that truly invincible ignorance is best left alone.