What? Of course you can base your political views on rationality. For example, climate change is literally an existential threat to life on this planet, so the rational thing to do would be to support policies that preserve the biosphere and therefore dramatically reduce carbon emissions. This is rooted in the core biological desire to reproduce and care for your offspring. Similar arguments can be made for all basic human and animal needs, like food, shelter, etc.

If your point is that everything is contrived and therefore irrational, then that precludes this entire conversation to the point of uselessness.