There are two important sub-questions here: what use is philosophy to any given individual, and what use is philosophy to society as a whole.

To the first sub-question I answer, given my characterization in an earlier thread of the faculties needed to do philosophy, that doing philosophy is literally practice at being a person, exercising the very faculty that differentiates persons from non-persons. Doing philosophy literally helps develop you into a better person, increasing your self-awareness and self-control, improving your mind and your will, and helping you to find meaning in the world, both in the sense of descriptive understanding, and in the sense of prescriptive purpose.

It is much like martial arts for the mind: as the practice of martial arts both develops the body from the inside and prepares one to protect their body from attacks from the outside, both from crude brutes but also from more sophisticated attackers who would twist the methods of martial arts toward offense rather than defense, so too philosophy develops the mind and will from the inside, and also prepares one to protect their mind and will from attacks from the outside, both from crude ignorance and inconsideration but also from more sophisticated attackers who would twist the methods of philosophy against its purpose, into what might better be termed "phobosophy". In a perfect world, the latter uses of either martial arts or philosophy would be unnecessary, as such attacks would not be made to begin with, but in the actual world it is unfortunately useful to be thus prepared; and even in a perfect world, with no external attackers, martial arts and philosophy are both still useful for their internal development and exercise of the body, mind, and will.



To the second sub-question, I answer that philosophy is the lynchpin of the entire chain of activities conducted by society, and so is instrumentally useful, in some distant way at least, toward any practical end whatsoever.

Every practical activity involves using some tool to do some job. That work may be the original job of keeping our bodies alive using the original tool of our bodies themselves, i.e. medicine and agriculture. It may be the jobs of making new tools to help with that, i.e. construction and manufacturing. Or multiplying and distributing our power to do that, i.e. energy and transportation industries. Or multiplying and distributing our control over that power, i.e. information and communication industries.

At the lowest level of abstraction away from the actual use of whatever tools to do whatever jobs, technological fields exist to maintain and administrate those tools, and business fields exist to maintain and administrate those jobs. A level of abstraction higher, engineers work to create the tools that those technologists administrate, while entrepreneurs work to create the jobs that those businesspeople administrate. Those engineers in turn heavily employ the findings of the physical sciences, which could be said to be finding the "natural tools" available from which engineers can create new tools tailored to specific needs. And though this step in the chain seems overlooked in society today, the ethical sciences that I envision could be said to find the "natural jobs" that need doing, inasmuch as they identify needs that people have, which we might also frame as market demands, toward the fulfillment of which entrepreneurs can tailor the creation of new jobs. And those physical and ethical sciences each rely on philosophical underpinnings to function, thereby making philosophy, at least distantly, instrumental to any and all practical undertakings across society.

I hold that the relationship of philosophy to the sciences is the same as that between administrative fields (technology and business) and the workers whose tools and jobs they administrate. Done poorly, they constantly stick their nose into matters they don't understand, and tell the workers, who know what they are doing and are trying to get work done, that they're doing it wrong and should do it some other, actually inferior, way instead, because the administration supposedly knows better and had better be listened to. But done well, they instead give those workers direction and help them organize the best way to tackle the problems at hand, then they get out of the way and let the workers get to doing work. Meanwhile, a well-conducted administration also shields the workers from those who would detract from or interfere with their work (including other, inferior administrators); and at the same time, they are still watchful and ready to be constructively critical if the workers start failing to do their jobs well. In order for administration to be done well and not poorly, it needs to be sufficiently familiar with the work being done under its supervision, but at the same time humble enough to know its place and acknowledge that the specialists under it may, and properly should, know more than it within their areas of specialty.

I hold that this same relationship holds not only between administrators and workers, but between creators (engineers and entrepreneurs) and administrators, between scientists (physical or ethical) and creators, and most to the point here, between philosophers and scientists. Philosophy done well guides and facilitates sciences, protects them from the interference of philosophy done poorly, and then gets out of the way to let the sciences take over from there. The sciences are then to do the same for creators, they to do the same for administrators, they to do the same for all the workers of the world getting all the practical work done.