Systems thinking can be seen as a reaction to the failure of natural science when confronted with complex, real-world problems set in social systems. Systems thinkers advocate using holism rather than reductionism in such situations. In systems theory, it's important to have perspective, as a very small observer of a single element may be oblivious to larger interactions that might be clear to a giant observer of the entire system. Systems theory suggests that knowledge of one type of system can be applied to many other types. By studying interactions and connections between the pieces of a system, the gained knowledge can be useful when confronted with other problems. Systems engineering encourages the use of modeling and simulation to validate assumptions or theories on systems and the interactions within them. Using system dynamics simulations enables one not only to observe events but also see patterns of behavior over time.