I've been wrong millions of times.
I've occasionally even been right, although that depends on whether you ask my wife.
But only a handful of times in my life have I been so completely certain about something that I would have bet my life on it, only to be proved wrong. This is the business one.
I rang the office one day and couldn't get through. I tried again from a different number. Still nothing. I checked the CCTV while it was ringing and saw the member of staff just sitting there.
He'd previously told me he didn't use the loudspeaker, so I'd ruled that out. No handset in his hand meant one thing to me: he was ignoring the phone.
I confronted him. He denied it. I was so certain I'd seen it with my own eyes that I called him a liar.
He still denied it, so I checked the call logs. He'd been on another call at the exact moment mine came in, on loudspeaker, exactly what he'd told me he didn't do.
I'd been wrong about the lie. He had broken a rule and concealed it, but I had accused him of something he hadn't done. Neither of us came out of it clean, but only one of us had been called a liar for something he hadn't done.
I apologised straight away.
It's one of the first things I tell new managers when they're considering disciplining a member of staff: never flat out call someone a liar.
Being certain doesn't make you right. Listen, gather the evidence and leave room for the possibility that you're wrong.
Sometimes even your own eyes give you the wrong answer.