Editing Philosophy of science (section)

===Observation inseparable from theory===
[[Image:Einstein cross.jpg|thumb|right|Seen through a telescope, the [[Einstein cross]] seems to provide evidence for five different objects, but this observation is theory-laden. If we assume the theory of [[general relativity]], the image only provides evidence for two objects.|alt=Five balls of light are arranged in a cross shape.|263x263px]]
When making observations, scientists look through telescopes, study images on electronic screens, record meter readings, and so on. Generally, on a basic level, they can agree on what they see, e.g., the thermometer shows 37.9 degrees C. But, if these scientists have different ideas about the theories that have been developed to explain these basic observations, they may disagree about what they are observing. For example, before [[Albert Einstein]]'s [[General relativity|general theory of relativity]], observers would have likely interpreted an image of the [[Einstein cross]] as five different objects in space. In light of that theory, however, astronomers will tell you that there are actually only two objects, one in the center and [[Gravitational lens|four different images]] of a second object around the sides. Alternatively, if other scientists suspect that something is wrong with the telescope and only one object is actually being observed, they are operating under yet another theory. Observations that cannot be separated from theoretical interpretation are said to be [[theory-laden]].<ref name="StanTheoryObs">{{cite web|url = http://plato.stanford.edu/entries/science-theory-observation/|title = Theory and Observation in Science|access-date = 2014-02-25|last1 = Bogen|first1 = Jim|year = 2013|website = Stanford Encyclopedia of Philosophy|archive-url = https://web.archive.org/web/20140227105420/http://plato.stanford.edu/entries/science-theory-observation/|archive-date = 2014-02-27|url-status = live}}</ref>

All observation involves both [[philosophy of perception|perception]] and [[cognitive process|cognition]]. That is, one does not make an observation passively, but rather is actively engaged in distinguishing the phenomenon being observed from surrounding sensory data. Therefore, observations are affected by one's underlying understanding of the way in which the world functions, and that understanding may influence what is perceived, noticed, or deemed worthy of consideration. In this sense, it can be argued that all observation is theory-laden.<ref name=StanTheoryObs/>