by no means exhaust the vital components of the system. The highway system as a whole consists of a highly designed, standardized, well-maintained, incredibly diverse set of objects and practices that are just as essential for the smooth transportation of the people using the system as are the vehicles that traverse it: the traffic lights, the signs, the rest stops, the paint on the road, the safety-rails, the traffic cones, and so on are as vital as the cars themselves. Even more saliently for the purposes of our discussion, consider all the knowledge that went into conceptualizing, constructing, and maintaining that system, and of the skills and knowledge that must be imparted to each driver before he or she is competent to control a ton of metal and plastic moving at 75 miles per hour: these skills (and the tens of thousands of man-hours behind their conceptualization and implementation) are likewise essential. Think of the actual production and maintenance of those roads, the hundreds of thousands of miles of concrete, construction, and cleanup— as well as the hours of political negotiations and legal regulations and labor disputes that sit behind every mile of that road. Only through the smooth operation of this system as a whole is actual use of the road—the sitting behind the wheel, listening to terrible music, with only some destination in mind—made possible.
If the previous comparison of philosophers to air-traffic controllers seems to elevate philosophy beyond its rightful station, then we might take comfort in the fact that, though we might play the role of the lowly dotted yellow line, this role is still deeply essential to the functioning of the whole. Philosophers are not scientists in just the same way that dotted yellow lines are not cars, or that air-traffic controllers are not pilots, or that traffic engineers are not commuters trying to get to work on time. Like our transportation analogues, though, philosophers have a vital role to play in the scientific project as a whole: a role of coordination,