What is the difference between rationalism and objectivism in a nutshell (if that is possible)?
Objectivist Epistemology has concepts as mental representation of existents. Rationalism is based on “pure reason”, ideas disconnected from reality.
Stated simply, rationalism merely relies on logic from whatever premises the subject wants, without concern for perceived reality. For example, one could start with the premise “Unicorns exist, and that unicorns are the source of life”, and from there infer whatever they want on those basis. The premises don’t need to be attached to perceived and perceivable reality.
Objectivism, on the other hand starts with observed reality as the foundation, and infers logically from there.
Rationalism is logic detached from perception.
Empiricism is (can be) perception detached from logic.
Objectivism is logic used with perceived reality as the base.
What is the difference between rationalism and objectivism in a nutshell (if that is possible)?
A rationalist believes it is possible to deduce reality a priori, starting from “self evident” truths.
Bob Kolker
Objectivism claims, with supreme confidence, that reality is knowable – and the same for all living creatures and unliving things. It claims that the truth about reality can be obtained by humans with certainty. Objectivism says that this reality, and these truths about it, exist objectively, impartially, and neutrally – and can be learnt and known in the same way.
Rationalism is “pure logic” or “pure reason” (as taught by Descartes, for example) unconnected to, or dependent on, the senses or practical experience. Thus this “pure thinking” is also unconnected to reality.
Using you mind in the rationalist way is supposedly pure and uncorrupted, and thus leads to more objective and more certain truth. Now, this is a good try and decently plausible, in my humble opinion.
But it ultimately makes no sense! Aren’t the mind and the thinking processes always corrupted by the senses and experience? And through them, isn’t the brain and act of thinking always corrupted, tainted, warped, and prejudiced by reality?
We want the brain and thinking processes to be thusly “corrupted, tainted, warped, and prejudiced” by the external world. This is how we learn about reality!
As far as I can tell, the “pure reason” of rationalism – while it has some surface appeal – is pure nonsense.