Here in the US we've seen major political parties completely realign themselves, Goldwater conservatives bear more resemblance to today's Democratic party than they do to today's GOP. Doesn't the fact that politics changes, imply that it's a reincarnation of opinion and tribalism, rather than a science rooted in fact (which is immutable)?
Not to put words in your mouth, I think the space between us is that I see a separation between policy and politics. I view politics as the science of cultivating power, and policy as something measurable and scientifically testable. Not a matter of opinion.
IMO opinion is a reflection of people's inability to commit to statistical facts, and operate using mathematical precision. There is actually no need to make decisions on the basis of opinion, if one has unlimited resources for computation, decisions are just optimization of a Bellman loss.