On a given set of 1000 questions, over time the trend has been to answer slightly more of them correct every year, progressively raising unstandardized scores, over the set of all IQ testees, since IQ testing was formalized in the 1950s.

Extrapolation is the most questionable statistical tool, and while extrapolation ad absurdum is a way to show a formal predicate logic argument to be incorrect or underspecified, it is an almost fully general attack against real datasets, which basically always have some trend line that ultimately passes sensible thresholds like zero bounds. Showing this, however you form the trend line, is not saying a whole lot.

Extrapolation prior to 1950 is not a very useful tool to evaluate intelligence trends, and this is entirely separate from the periodic recalibration of IQ tests to keep the average at 100 (however many correct answers out of 1000 this corresponds to).