Rationalism is an erroneous epistemological method (not to be confused with rationality) signified by separation of ideas from reality, improper reliance on deduction from axioms, false demand for "comprehensiveness" and "systems, " and a general tendency to intrincisism.
The methodology of rationalism begins with an axiomatic foundation, ideally founded on a self-evident, irrefutable idea. An axiomatic foundation allows the rationalist to dispense with the need for context in his argument, or any premises upon which it is based. He then proceeds deductively from that foundation, deducing conclusions without reference to facts or examples. A deductive process allows the rationalist to avoid the need to use facts and examples in his argument. Once a rationalist comes up with a theory, he holds it as an absolute, without attempting to integrate it with is prior knowledge or to consider how new knowledge might affect it. By avoiding the contextual, hierarchical nature of knowledge, the rationalist attempt to avoid any contradiction between his abstract ideas and the rest of his knowledge.
The disconnected nature of his knowledge causes a rationalist to flounder between absolute certain and ignorance. Since his ideas lack context or anchors to reality in the form of integration with the rest of his knowledge, challenges in the form of objections or new facts can cast into doubt his previous certainty about a topic. Since rationalism is detached from reality, rationalists are unable to apply abstract ideas to concrete instances -- and therefore must view each new concrete as a new situation. Despite their superficial commitment to reason, rationalists therefore become chronic empiricists, since they have no means to analyze a given situation in terms of basic principles. Objectivism refutes the basic rationalist approach by stressing that knowledge must be based on reality, and therefore can only be attained by keeping ones thinking close to reality at every stage of the process through application to concretes and integration with the rest of one's knowledge. An intellectual analysis must therefore begin with the context necessary for a particular thought process. Furthermore, rather than viewing concretes as isolated cases, the Objectivist approach attempts to connect instances to ones existing knowledge, and to look for patterns and principles within the evidence available. The Objectivist gets his ideas from reality and aims to validate new knowledge against reality while the rationalist gets his ideas from rationalizations and attempts to escape the need to confirm the validity of his ideas.