if p then q,
not q,
therefore, not p.
For example,
If this is wood, then it will float on water.
It does not float on water.
Therefore, this is not wood.
The peculiarity of the reductio argument is the nature of q. Q must be either a contradiction or plainly and certainly wrong.
How does this apply to Ukraine? Ukraine is a liberal democracy. A liberal democracy is a representative democracy in which thousands or millions elect an office holder. In a liberal democracy it is assumed that people are competent to elect their representatives.
This Sunday, April 21, 2019, Ukrainians will hold the run-off elections for its president. And by the estimate of the polls, Volodymyr Zelensky will be the overwhelming winner.
You say, so what? The fact of the matter is that he is winning on the basis that he is a well know television comedian, who for the last two years has starred in a television series “Servant of the People,” playing the role of a history teacher who by a quirk is elected the president of Ukraine. Otherwise, Zelensky has made no political pronouncements other than such generalities as wanting peace. It is solely on the basis of knowing a virtual, make-believe president, that the people will elect their next president. It is the ridiculous conflation of the actor Volodymyr Zelensky being identified with Vasyl Holoborodko (the virtual president).
This is a unique occurrence. It resembles the scenario in the British television series Dark Mirror, in which a cartoon bear, Waldo, runs as a candidate for political office, and gets a substantial vote. See below:
Here is the reductio ad absurdum:
If people are competent to elect a president, then the president chosen will be Holoborodko, who is believed to be Zelensky.
But Holoborodko is not Zelensky
Therefore, people are not competent to elect a president.
Daniel Dennett on Reductio ad Absurdum