In CBT circles, there are two dimensions of thought: validity and utility. Validity is whether or not a belief is true; utility is whether or not it's useful. Different therapists have different beliefs about validity and utility...recently, a lot of therapists are looking only at utility. They don't believe in truth, so trying to figure out whether or not someone's beliefs are true strikes them as a waste of time.

Ellis is big on "rational" talk, but surprisingly he's really talking about utility. To Ellis, a rational belief is a helpful belief, and an irrational belief is an unhelpful one.