If the purpose of guns were to kill, cops would not be allowed to have them because, in civilized countries contrary to James Bond movies, they don’t have a license to kill.
A tool or instrument, observed Friedrich Hayek, cannot be defined outside of human purposes. For example, the definition of a hammer must include what most people want it for, that is, as the online Merriam-Webster dictionary tells us, “for pounding.” In his 1942 Economica article “Scientism and the Study of Society” (reproduced in his The Counter-Revolution of Science), Hayek noted:
Take the concept of a “tool” or “instrument,” or of any particular tool such as a hammer or a barometer. It is easily seen that these concepts cannot be interpreted to refer to “objective facts,” that is, to things irrespective of what people think about them. … If the reader will attempt a definition he will soon find that he cannot give one without using some term such as “suitable for” or “intended for” or some other expression referring to the use for which it is designed by somebody. And a definition which is to comprise all instances of the class will not contain any reference to its substance, or shape, or other physical attribute.
An automobile is, to quote Merriam-Webster again, an “automotive vehicle designed for passenger transportation.” People use it to go from point A to point B. Under this general purpose lie many specific ones. For many, A will be mainly their homes and B, their workplaces. Some, no doubt, will use their car to go and commit a bank robbery, and escape afterwards. For terrorists, the space between point A and point B may be any place where there are pedestrians to crush. Collectors and museums may even dispense with the transportation function, although the original purpose remains part of the attraction.