Last year the Lalolah River was ranked by the Sunvale Water Commission as the most polluted of the fifteen rivers in ...

Irina on January 15, 2020

@sprozes,

The argument tells us that last year the river was ranked as the most polluted in the district, but this year it is ranked only as the third most polluted. It then proceeds to conclude that "measures taken to clean up the river must be working." This conclusion is unsupported by the premises because it is equally likely that other rivers became even more polluted rather than that the river previously ranked first got cleaned up. The argument's flaw is in the fact that it overlooks this possibility, or in other words - it equates a decrease relative to the other ranked rivers with an absolute decrease when the river could have stayed as polluted as last year or became even more polluted but whereas the other rivers became polluted to even greater degree.