How did European countries justify their imperialism?

Many Europeans who supported imperialism argued that new
colonies, and the new markets they brought, were necessary to avoid over-production,
which would lead to economic depression. (Opponents of imperialism, such as John Hobson,
said that was nonsense, but it was the reason that Lenin described imperialism as the
"final stage of capitalism.) Also, it's important to note that many examples of
imperialism, especially British imperialism, began with investment in foreign countries.
When political events in those countries jeopardized the capital invested in them,
business leaders prevailed on governments to intervene militarily, which sometimes lead
to almost direct rule. This happened most obviously in
Egypt.

The issue of raw materials, as well as the "White
Man's Burden," both referenced above, were very important, as was social Darwinism,
which justified imperialism as part of a natural stuggle between
races.

One of the more intriguing arguments imperialism is
that the acquisition of colonies in Africa and elsewhere tended to distract from the
class struggles prevalent in the industrialized European societies. Leaders appealed to
patriotism and to the jobs that imperialism supposedly created to get popular support
for acquiring territories overseas.