In the end, philosophy offers the means of separating the workable from the absurd -- logic. It is worth reminding ourselves that Plato said of his Academy: let none enter but those who have mastered geometry. That was the geometry of Euclid, a geometry that depended upon logic that demonstrated much counter-intuitive knowledge was undeniable truth. Euclidean geometry and its descendants are the first introduction of high-school students to formal logic as necessary for proofs. Even today it is high-school geometry that separates the future college kids from everyone else, likely because it introduces formal logic essential to advanced thought in anything. Shapes? Geometry is still fascinating, but one would not be hurt too badly in most of life if one believed that bigger triangles have bigger angles than little triangles. (The angles of a 3-4-5 triangle are exactly the same as those of a 51-68-85 triangle, thank you).
Philosophers as different as Lukacs and Ortega y Gassett may disagree on the core of political reality (Marxism vs. romantic conservatism), but they agree on the same iron laws of logic to establish the reliability of a line of reasoning, and they recognize objective reality (typically, statistical evidence) as the test of truth. A really-bad philosophical construction, let us say racial bigotry (and modern antisemitism is racist in practice), fails because it is easy to pick apart for its shabby logic as well as consequences that become increasingly absurd. An anti-black racist can easily use Mike Tyson as an example of all that he finds wrong with black people... but ignores Neil de Grasse Tyson, who does have five things in common with Mike Tyson: masculinity, having made much money, the same surname, being black, and being from and living in the Greater NYC area.
It is impossible to prove one's core values. Believe certain things, and one is an Islamic fundamentalist. Believe some other things, and one is a Marxist. I am evidently neither, and I need not go into the details. People can look at what I post and glean my core values. We all have reality to hammer away at stupidity; we may simply disagree on how to use it.
The greatest evil is not now done in those sordid "dens of crime" (or) even in concentration camps and labour camps. In those we see its final result. But it is conceived and ordered... in clean, carpeted, warmed and well-lighted offices, by (those) who do not need to raise their voices. Hence, naturally enough, my symbol for Hell is something like the bureaucracy of a police state or the office of a thoroughly nasty business concern."
― C.S. Lewis, The Screwtape Letters