"I don't know" done well

Sooner or later someone will ask a question you can't answer. Bluffing is the worst response: experts in the room will notice, and your credibility on everything else drops. "I don't know" said well builds trust.

How to say it well

• Be direct: "I don't know."
• Say what you do know: "We tested it on three regions; we haven't tested other climates."
• Offer a reasoned guess, labelled as a guess: "My guess is it would drop somewhat, because lighting differs, but we'd need to test it."
• Turn it forward: "That's a good direction for future work" or "Can I follow up with you by email?"

Then do follow up if you offered to.

Separate "unknown" from "I didn't check"

If the question shows a real gap in your work, acknowledge it honestly: "That's a fair point. We didn't control for that; it's a limitation." Admitting a limitation calmly is more convincing than defending a weak point.

Why it works

Audiences trust speakers who know the edges of their knowledge. Science advances by finding what isn't known yet; a good unanswered question is a gift.

RememberNever bluff. Say "I don't know", share what you do know, label any guess as a guess, and offer to follow up.