@UlrikeHahn Thank you for your essay! It feels right to me, the different modes of engagement are important. However, I think that they are not necessarily distinctive features. A politician can be successful by using the scientific mode of engagement and consider all evidence, and a "scientist" may bulldoze competitors (Lysenko). The key difference seems to be what counts as success: power in politics and knowledge in science. These two different aims are of course not independent of the two modes of engagement. This is true especially at a time of increasing political polarization, when the tension that you discuss in your essay matters a lot and politicians are tempted to gain power by deviating from the scientific mode of engagement.
My feeling is that the whole system becomes unsustainable if politics deviates too much from what is known. Producing good science and infusing the public discourse with good science then seems to be useful.
I have tagged this post as my opinion. This is not really a solution to the problems addressed towards the end of your essay, but it may help to convey that this post lacks scientific rigor. I am confused as well.