Cognitive science is a branch of science which studies the nature of mental processes and the operation of the mind, particularly functions such as perception, attention, consciousness and memory. Unlike psychology it does not confine itself to humans, nor even to animals, but seeks laws that would apply to non-biological beings or alien life forms, as long as they could be said to have a 'mental process'. As described, this is an expansive and exhilarating vista. However, it should be recognized that cognitive science is not equally concerned with every topic which might bear on the nature and operation of the mind. Social and cultural factors, emotion, consciousness, non-human animals, comparative and evolutionary approaches, connectionism, nonsymbolic or nonpropositional AI, and non-mathematical problem solving are frequently de-emphasized or excluded outright, often on the basis of key philosophical conflicts. Nonetheless, it is possible to conceive of cognitive science as more broadly occupied with the mental however and wherever it is implemented.
Cognitive science has much to its credit. Among other accomplishments, it has given rise to models of human cognitive bias and risk perception, and has been influential in the development of behavioral finance, part of economics. It has also given rise to a new theory of the philosophy of mathematics, and many theories of artificial intelligence, persuasion and coercion. It is has made its presence firmly known in philosophy of language and epistemology - a modern revival of rationalism - as well as constituting a substantial wing of modern linguistics.
The field, reflecting this broad concern, is highly inter-disciplinary. Cognitive Science may be seen to consist of, take part in, and/or collaborate with psychology (especially cognitive psychology), linguistics, neuroscience, artificial intelligence (neural network research in particular), and philosophy (especially philosophy of mind and philosophy of mathematics, but also with applications in philosophy of science). Cognitive science is usually seen as compatible with and interdependent with the physical sciences, and makes frequent use of the scientific method, as well as simulation/modelling, often comparing the output of models with aspects of human behavior. Still, there is much disagreement about the exact relationship between cognitive science and other fields, and the inter-disciplinary nature of cognitive science is largely both unrealized and circumscribed (for example, it is hard to imagine much useful issue from a relationship with linguistics which does not take up a Chomskyan program.) It should again be realized that the interdisciplinary scope of cognitive science does not extend into all areas which are concerned with the nature and operation of the mind (nor should it), though a broader perspective is always possible.
The key difference between cognitive psychology and prior versions of psychology was that the former assumed that internal mental process was investigatable by empirical methods, not just quasi-empirical methods.
Cognitive science further assumes that either kind of method is valid, and that cognition (being formally defined) does not depend on the substrate it takes place in (like scientific investigations, robotic copying of animal behavior, and software simulating human language), and therefore investigations of these processes provides insight into human and near-human (e.g. chimpanzee), cognition.
Assertion of equivalence of Euler's Identity (basis of complex analysis in mathematics) with basic cognitive processes, George Lakoff and Rafael Nunez[?], 2000. Basis of cognitive science of mathematics.
One of the most universally affirmed ideas of cognitive science is the importance of the unconscious mind; many, if not most, important mental processes are considered to be inaccessible to the conscious, introspecting observer. ... Anyone who has ever forgotten something and then remembered it will be familiar with the idea that some things are simply unavailible to you at some times. ... Linguists find on one hand that people - even the young and the uneducated - form sentences in ways seemingly governed by very complicated rule systems. On the other hand, the same people are remarkably inept at identifying the rules that lie behind their own speech, and linguists must resort to very indirect methods to determine what those rules might be. Thus, if speech is indeed governed by rules, those rules seem to lie below conscious consideration. This may leave cognitive science's claim to study what we think and feel in the same awkward position occupied by Freud's theories...
Probably most cognitive scientists believe the Mind/Brain Identity Theory, the idea that, whatever "mind" and "intelligence" are, they are rooted strictly in the brain, and do not make use of, depend on, or interact with anything non-physical. Nonetheless, there is reasonable consensus that there is sense in talking about the organization of the mind without talking about the organization of the brain, and that cognitive scientists are not simply neuroscientists. Often the justification for this takes place by reference to different levels of analysis. A cognitive scientist is likely to assert that what he says about reasoning is true at the symbolic level of abstraction, while what the neuroscientist says is true at the physical level implementing the symbolic level (much as your computer as a physical object implements a virtual machine on which your word-processor runs).
Symbolic vs Connectionist approaches There is some debate in the field as to whether the mind is "best" viewed as a huge array of small but stupid elements (i.e. neurons), or as a collection of higher-level structures, such as "symbols", "schemas", "plans", and rules. One way to view the issue is whether it is possible to accurately simulate a human brain on a computer without accurately simulating the neurons that seem to make up the human brain.
Cognitive Science tends to view the world outside the mind much as other sciences do; thus it has an objective, observer-independent existence.
The term "cognitive" in "cognitive science" is "used for any kind of mental operation or structure that can be studied in precise terms." (Lakoff and Johnson 1999) This conceptualization is very broad, and should not be confused with how "cognitive" is used in some traditions of analytic philosophy, where "cognitive" has to do only with formal rules and truth conditional semantics. (Nonetheless, that interpretation would bring one close to the historically dominant school of thought within cognitive science on the nature of cognition - that it is essentially symbolic, propositional, and logical.)
The earliest entries for the word "cognitive" in the OED take it to mean roughly pertaining to "to the action or process of knowing". The first entry, from 1586, shows the word was at one time used in the context of discussions of Platonic theories of knowledge. Most in Cognitive science, however, presumably do not believe their field is the study of anything as certain as the knowledge sought by Plato.