Descartes was the first of the modern rationalists and has been dubbed the ‘Father of Modern Philosophy.’ Much subsequent Western philosophy is a response to his writings, which are studied closely to this day.
In epistemology, rationalism is the view that “regards reason as the chief source and test of knowledge” or “any view appealing to reason as a source of knowledge or justification”. More formally, rationalism is defined as a methodology or a theory “in which the criterion of the truth is not sensory but intellectual and deductive”.
Rationalists believe reality has an intrinsically logical structure.
Rationalists argue that certain truths exist and that the intellect can directly grasp these truths. That is to say, rationalists assert that certain rational principles exist in logic, mathematics, ethics, and metaphysics that are so fundamentally true that denying them causes one to fall into contradiction. Rationalists have such a high confidence in reason that empirical proof and physical evidence are unnecessary to ascertain truth – in other words, “there are significant ways in which our concepts and knowledge are gained independently of sense experience”.
Empiricism is a theory that states that knowledge comes only or primarily from sensory experience. One of several views of epistemology, the study of human knowledge, along with rationalism and skepticism, empiricism emphasizes the role of experience and evidence, especially sensory experience, in the formation of ideas, over the notion of innate ideas or traditions; empiricists may argue however that traditions (or customs) arise due to relations of previous sense experiences.
Empiricism in the philosophy of science emphasizes evidence, especially as discovered in experiments. It is a fundamental part of the scientific method that all hypotheses and theories must be tested against observations of the natural world rather than resting solely on a priori reasoning, intuition, or revelation.
Humanism is a philosophical and ethical stance that emphasizes the value and agency of human beings, individually and collectively, and generally prefers critical thinking and evidence (rationalism, empiricism) over the acceptance of dogma or superstition. The meaning of the term humanism has fluctuated according to the successive intellectual movements which have identified with it.
Generally, however, humanism refers to a perspective that affirms some notion of human freedom and progress. In modern times, humanist movements are typically aligned with secularism, and as of 2015 “Humanism” typically refers to a non-theistic life stance centred on human agency and looking to science rather than revelation from a supernatural source to understand the world.