This analogy makes sense if you assume the conclusion that the argument for the post being a Basilisk is incorrect, but not as an argument for convincing people that it’s incorrect. To evaluate whether the argument is correct, you have to study the argument itself, there is no royal road (the conclusion can be studied in other ways, since particular proof can’t be demanded).
(See this summary of the structure of the argument.)
This analogy makes sense if you assume the conclusion that the argument for the post being a Basilisk is incorrect, but not as an argument for convincing people that it’s incorrect. To evaluate whether the argument is correct, you have to study the argument itself, there is no royal road (the conclusion can be studied in other ways, since particular proof can’t be demanded).
(See this summary of the structure of the argument.)