Laputa is a flying island whose inhabitants are solely intellectualls who devote themselves to the disciplines of sciences such as mathematics and astronomy. It is clear these people can only think abstract thoughts and are unable to practically apply their knowledge. One example is that they have mastered the principles of magnetics and levitation, but are unable to make proper clothes or build good buildings, because they take all meausurements with instruments such as a compass rather than a measuring tape. In addition, the people of this island are so lost in their abstract thoughts that they all need servants to remind them of what they were talking and of what they need to do.
It is clear that in this satire Swift is satiring the dangers of taking the power of reason too far. Reason, although clearly beneficial in the scientific advances it has fuelled, can only be followed with a good dose of common sense for it to be of any practical use.