What impact did slave rebellions have on attitudes toward slavery?

The major impact that slave rebellions had on attitudes
towards slavery was to harden them and to make Southerners more apt to support slavery
and to oppose efforts to free slaves or to improve the conditions of
slavery.

Slave rebellions filled Southerners with fear. 
The rebellions made Southerners fear that their lives could be taken by discontented
slaves.  The fact that some rebellions included free blacks worried whites as well. 
These things made them think that they only way to preserve their own safety was to make
slaves too afraid and timid to try to rebel and to prevent the number of free blacks
from getting higher.  This led to harsher laws governing slaves in, for example, the
time after Nat Turner's rebellion.

Later rebellions did
also harden the attitudes of Northern abolitionists.  They made abolitionists even more
certain that slavery was a great evil since slaves were willing to kill and be killed to
try to end it.

In these ways, slave rebellions did not
change minds about slavery.  They simply made people more certain of the opinions they
already held.