Political perspectives can roughly be grouped into three historical camps: Conservatism, (classical) Liberalism, and Marxism.
The essential difference between these schools is in their solution to the problem of human values. Liberals see individuals as rational, self-interested, and autonomous beings who can best resolve their conflicting material and spiritual values through voluntary cooperation. This means advocating a free market with a free marketplace of ideas (i.e. a pluralistic society) being its essential corollary.
Conservatism and Marxism also sees the individual as self-interested, but therefore as fundamentally irrational, corrupt, and unable to resolve conflicting values independently. Conservatives believe that individual desire is inherently corrupting and therefore advocate centralized guidance and control of spiritual values, and prohibition of material goods which might lead to spiritual corruption. Marxists believe that the pursuit of material goods is inherently violent and conflicting, and the essential controls must be of material pursuits. Marxists belittle ideas as irrelevant and advocate control of self-interested motivates through centralized social structures such as compulsory state-run schools. Conservatives are explicitly opposed to the marketplace of ideas, while Marxists explicitly view ideas as irrelevant, but in practice ruthlessly suppress dissent when it conflicts with their policy goals.
Since man is an integrated being, both Conservatives and Marxists end up advocating the same policies in the downward spiral to prevent the perverse consequences of the controls they instrument. Unchecked, they both lead to tyranny.
It should be noted that these are only tendencies and the vast majority of people are some combination of these three perspectives. Judging intellectuals means evaluating the particular combination of these perspectives. Furthermore, these perspectives are not primaries, but derivates of a basic perspective of human nature. This means that political views rarely change directly, but rather filter up through changes in a person’s basic view of human nature.