Logic issues

[ReneZ]

A typical issue is that evidence is not weighted on its objective strength, but on whether it is favourable or unfavourable to one's thoughts.

This issue is indeed very common, especially if it comes to an undeciphered writing system.

It is very common indeed, and can be found in all types of hypotheses about the Voynich MS, including theories about the origin, identifications of illustrations, etc.
It is closely related to 'confirmation bias' and I was intrigued to see the acute description of this by Francis Bacon, centuries ago already, in a recent post by Koen.