If we consider the various episodes of The Adventures of Huckleberry Finn that feature groups in action, we will see many examples of the folly of "collective thinking" or group action.
It is a group that goes around looking for a dead Huckleberry Finn early in the novel, firing off a canon to bring his body up from the river. Collectively, the town seems to "know" that Huck is dead. Huck feels no danger of being discovered by "the town" but he is very afraid of being found out by individuals who may be lurking on the island. This episode suggests a commentary on the intelligence or the tendency to achieve insight of a group (as opposed to an individual).
In the case of the feuding families, we see a similar commentary but this time it is one skewed toward moral insights. There, individuals are capable of falling in love across family lines yet the groups (the families) are incapable of recognizing the arbitrary nature of their continued dispute. Once the dispute becomes historic, it is essentially only founded on a difference in last names. Individuals (Sophia and Harney) are able to get past this formal difference and see each other as capable of love and companionship.
The cowardice of collective (or mob) action is explicitly dealt with in Chapters XXI and XXII, where Sherburn kills Bogs then diffuses a mob with a strongly worded speech. There a single man stands up to a crowd of townspeople and has a victory in the conflict because of his moral strength, which is greater than that of the gathered group of cowards who would not act individually.
Many more examples crop up in the novel where individuals are able to swindle, manipulate or outsmart the group.
Of course, the novel's most pointed commentary on individual man versus collective man comes in Huckleberry Finn's story. Huck battles against his conscience, which has been developed over his lifetime and imbued with notions of racism, dehumanizing ideas, false righteousness, etc. The formality of Huck's views, described always as categorical and unbending, are the product of collective thinking (e.g., society).
If Huck were to agree with the morality of collective man, he would have to turn Jim over to the authorities so that he could be returned, as property, to Miss Watson. Huck instead chooses to perform an act of great moral strength and courage and chooses to help Jim maintain his freedom and achieve permanent liberty by escaping the region.
It was a close place. I took it up, and held it in my hand. I was a-trembling, because I'd got to decide, forever, betwixt two things, and I knowed it. I studied a minute, sort of holding my breath, and then says to myself:
“All right, then, I'll go to hell”—and tore it up.
Put another way, Huck's conflict becomes a commentary on morality versus the law.
"If breaking the civil law is a sin, resulting in his eternal condemnation, he is willing to accept it. He chooses moral law and refuses to betray his friend. Huck chooses love over law" (eNotes).
Although Huck has been raised in a culture that equates religious law with civil law (so that it would be a sin to help Jim escape to become something other than someone's property), the individual realizes that there is another level of moral reasoning to consider. There is a deeper obligation for the individual than that of adhering to society's norms. One must do what one feels is right.
This precept speaks directly to the idea that the individual bears a moral power that is at least equal to the moral power of any group, if not greater. Also, this idea indicates a philosophical conclusion that suggests that those who would take shelter in the collective and so attempt to evade moral responsibilities are often acting immorally. Only when one takes responsibility to weigh questions of right and wrong can one be said to be acting morally. This can only happen on an individual level.