Generally speaking, science endeavors to find useful models of reality to try and explain why an observation or pattern of observations that we see actually occurs. For example, in chemistry we can use a model for a gas in a container where we describe the gas as consisting of particles colliding with the sides of the container thus giving rise to gas pressure. In psychology, depression has been described in some cases as a lack of the neurotransmitter serotonin in the brain. Traditionally science has proceeded along two main lines: the natural sciences that study the natural world (e.g., physics, cosmology, chemistry, geology, zoology etc.) and the social sciences that study human behavior and society (e.g., psychology, anthropology, sociobiology etc.)
However, the differences between these two streams have become somewhat blurred, with some crossing over (e.g., neuroscience, genetics). Science depends on a number of assumed beliefs, namely: (1) The universe is an ordered and rational place so that doing science makes sense (why should it?); (2) The underlying “laws of nature” governing the universe tend to be mathematical and are in a sense “beautiful” (to the mathematician!), and the question is why mathematical;
(3) The laws of nature are stable over time and are the same throughout the part of the universe that we can reach with our instruments (why not chaos?); and (4) Our minds are rational and we are capable of uncovering the laws of nature (why should we be able to do this?).