John C. Lilly said-

In the province of the mind what one believes to be true,
either is true or becomes true within certain limits.
These limits are to be found experimentally and experientially.
When so found these limits turn out to be further beliefs to be transcended.
In the province of the mind there are no limits. However, in the province of the body there are definite limits not to be transcended.

Justifications

A quote from Robert Anton Wilson from his book THE WIDOW'S SON portrays the way we think.

All of this was justified, in the minds of men who were not totally vicious or fanatical, by the atrocities which the Irish Catholics had committed in their several rebellions, and by the hundreds of years of religious wars throughout Europe in which ferocity was the rule and massacres on both sides left each sect convinced the other was barbaric and inhuman.
Jonathon Swift, who had been part of the Protestant ruling class in Ireland in the worse of the Penal era, wrote once that the English Protestants might as well eat the babies of the Irish Catholics, since they already devoured rest of the country. This led people to say, later, that Swift was mad, or embittered, or something like that.
Swift also said, “We have enough religion to hate each other, but not enough to love each other.” That led people to say he was a cynic.

Most of the Irish in 1771 could read neither their own language nor the English of the conquerors. They were not only illiterate and impoverished but dirty, smelly, ignorant and superstitious. The Penal Law accomplished that much.

When humanitarians like Swift or Burke or such types would argue in relieving the Irish from the Penal Laws, common-sense people therefore had an answer to this sentimental liberalism. The answer was that the Irish could not be helped because they were obviously an illiterate, ignorant, dirty and smelly people.