Theories

thumb|200px|Sketch from Charles Darwin's Notebooks on Transmutation of Species (1837), arguably the first example of a phylogenetic tree. (1) represents a common ancestor, the barred branches represent extant descendants, and the unmarked branches represent extinct descendants. A theory is, in general, any hypothesis or set of ideas about something, formed in any number of ways through any sort of reasoning for any sort of reason.

An explanation is a set of statements usually constructed to describe a set of facts that clarifies the causes, context, and consequences of those facts. It may establish rules or laws, and clarifies the existing rules or laws in relation to any objects or phenomena examined.

physics principle stating that the laws of physics must be the same in all reference frames

hypothetical star orbiting the Sun, responsible of extinction events

political science theory about the expression of opinion

political and government system, where several sovereign states give up and share part of their sovereignty for their common governance

translation studies concept

Classification is the activity of assigning objects to some pre-existing classes or categories. This is distinct from the task of establishing the classes themselves (for example through cluster analysis). Examples include diagnostic tests, identifying spam emails and deciding whether to give someone a driving license.

In international relations, intergovernmentalism treats states (and national governments in particular) as the primary actors in the integration process. Intergovernmentalist approaches claim to be able to explain both periods of radical change in the European Union because of converging governmental preferences and periods of inertia because of diverging national interests.

explanation of human behaviour in terms of genetic and cultural evolution

theory regarding ancient Greek religion

theory that characterizes object complexity

belief in numerous life-bearing "worlds"

comparative anthropology and semiotics that seeks to define the heuristic concept of culture in operational and/or scientific terms

electric charge treated as continuously distributed in space

In politics, the term "incrementalism" is also used as a synonym for Gradualism.

theoretical concept within philosophy

combination of relativistic and quantum concepts

Mathematical theories

1976 theory developed by Sandra Ball-Rokeach and Melvin Defleur

Translation studies theory

how to produce solar power