The Organization operates under the confusing concept of 'Provisional Infallibility'.
On the one hand, information contained in the Watchtower is from God's Holy Spirit and and so should be accepted without question; on the other hand, the Watchtower admittedly contains significant mistakes.
The Organization uses the irrational concept that Holy Spirit directs them but they are not inspired. This is illogical - inspired means to be directed by Holy Spirit. The concepts of infallibility and inspiration are simple, yet discussing them in line with Watchtower teachings becomes complicated because by definition it is impossible to have direction of Holy Spirit but not be inspired.
According to The American Heritage® Dictionary of the English Language, Fourth Edition:
Infallible; "Incapable of erring" (therefore to be infallible means to be perfect)
Inspire; "to affect, guide, or arouse by divine influence" (or in other words inspired means to be directed by Holy Spirit)
Therefore, if the Organization claims the direction of Holy Spirit it is by definition claiming to be inspired. In this case, it cannot make mistakes, by definition, it should be infallible in the same way the Bible is infallible.