Science as a collective institution aims to produce more and more accurate natural explanations of how the natural world works, what its components are, and how the world got to be the way it is now. Classically, science’s main goal has been building knowledge and understanding, regardless of its potential applications — for example, investigating the chemical reactions that an organic compound undergoes in order to learn about its structure. However, increasingly, scientific research is undertaken with the explicit goal of solving a problem or developing a technology. Along the path to that goal, new knowledge and explanations are constructed. For example, a chemist might try to produce an antimalarial drug synthetically and, in the process, discover new methods of forming bonds that can be applied to making other chemicals. Either way (so-called “pure” or “applied” research), science aims to increase our understanding of how the natural world works.

The knowledge that is built by science is always open to question and revision. No scientific idea is ever once-and-for-all “proven” Why not? Well, science is constantly seeking new evidence, which could reveal problems with our current understandings. Ideas that we fully accept today may be rejected or modified in light of new evidence discovered tomorrow. For example, up until 1938, paleontologists accepted the idea that coelacanths (an ancient fish) went extinct at the time that they last appear in the fossil record — about 80 million years ago. But that year, a live coelacanth was discovered off the coast of South Africa, causing scientists to revise their ideas and to investigate how this animal survives in the deep sea.

Despite the fact that they are subject to change, scientific ideas are reliable. The ideas that have gained scientific acceptance have done so because they are supported by many lines of evidence and have generated many expectations that hold true. Such scientific ideas allow us to figure out how entities in the natural world are likely to behave (e.g., how likely it is that a child will inherit a particular genetic disease) and how we can harness that understanding to solve problems (e.g., how electricity, wire, glass, and various compounds can be fashioned into a working light bulb). For example, scientific understandings of motion and gases allow us to build airplanes that reliably get us from one airport to the next. Though the knowledge used to design airplanes could be modified and built upon, it is also reliable. Time and time again, that knowledge has allowed us to produce airplanes that fly. We have good reason to trust accepted scientific ideas: they work!