“Pragmatism examines the truth of theories or beliefs in terms of the success of their practical application. The pragmatic truth criterion evaluates science in terms of its products that benefit humanity.” Jose A. Martinez-Diaz
If the evidence no longer backs the theory the theory has to change.
That can be really tough to do. When we have believed something to be true for a long time it can be very hard to admit what we believed, and did as a result of that belief, is no longer true and that change needs to happen. We can actually go through a grieving process for the old belief.