Competition can have both beneficial and detrimental effects. Many evolutionary biologists view inter-species and intra-species competition as the driving force of adaptation and ultimately, evolution. However, some biologists, most famously Richard Dawkins, prefer to think of evolution in terms of competition between single genes, which have the welfare of the organism 'in mind' only insofar as that welfare furthers their own selfish drives for replication. Some social Darwinists claim (controversially) that competition also serves as a mechanism for determining the best-suited group, politically, economically, and ecologically.

On the negative side, competition can cause injury to the organisms involved, and drain valuable resources and energy. Human competition can be expensive, as is the case with political elections, international sports competitions, and advertising wars. It can lead to the compromising of ethical standards in order to gain an advantage; for example, several athletes have been caught using banned steroids in professional sports in order to boost their own chances of success or victory. And it can be harmful for the participants, such as athletes who injure themselves exceeding the physical tolerances of their bodies, or companies that pursue unprofitable paths while engaging in competitive rivalries.