When one is religiously committed to a philosophy, one will do anything but admit the philosophy is flawed.
We see it in the Republican party - "tax cuts for the wealthy will create jobs!" is the mantra. When the biggest tax cuts for the rich in the history of the country are pushed through, and 11 years later we're still in the job doldrums, well, that doesn't prove the philosophy wrong, it just means they weren't cut enough! Yeah, that's the ticket!