The person changing their view deserves to be judged by the new view they now hold.

Changing your mind gets treated as evidence of unreliability rather than of thinking. The old position is held up as the real one, the new one as convenient, and the person ends up answering for something they no longer believe. That makes updating expensive, so fewer people do it, and everyone’s arguments become more entrenched than their actual opinions.

When somebody tells you they see it differently now, respond to what they are saying today rather than to their file. You can be curious about the change without treating it as a confession. Do the same for yourself, since the person hardest on you for changing is often you.