Human Rationality and the Limits of Scientific Knowledge

Understanding Rationality and Knowledge

Rationality is the specific feature that distinguishes humans from other animals. It enables humans to know and act on appropriate reasons, remaining firm and secure.

Rationalism vs. Empiricism

• Empiricism: What is perceived by the senses is real.
• Empiricism: The mind begins as a tabula rasa.
• Rationalism: Reason discovers within itself the first principles of knowledge.
• Rationalism: The senses deceive us.

Characteristics of Sensations

• Qualitative: Each sense always reacts the same way, regardless of the nature of the stimuli.
• Selective: Of the stimuli surrounding us, only a few can produce sensations.
• Inexact: They are not an exact copy of the stimuli; everything influences the sensations.
• First Level of Knowledge: We perceive objects as wholes, more or less defined, and recognize their qualities.

The Psycho-Physical Process of Sensation

First Phase: Excitement. The action of stimuli on the nerve endings of the organs, including both external and internal stimuli.

Second Phase: Conduction. The excitement of the sense organs becomes nerve current information that leads to brain neurons.

Third Phase: Interpretation. Impulses reach the brain centers where they are interpreted, sending other effector impulses to the muscles, etc.

Skepticism, Realism, and Relativism

Skepticism: A current of knowledge that questions and/or denies the human capacity for firm and sure knowledge; the most one can obtain are more or less probable opinions.

Realism: A set of theories asserting the ontological distinction between the subject and the known object; the object exists independently of the mind. We perceive objects of reality in a direct way.

Relativism: Denies the existence of absolutely true universal knowledge because it always depends on the person's point of view.

Modern Science and the Limits of Knowledge

Modern science identifies limits to human knowledge through the theory of special relativity and the uncertainty principle.

1. Special Relativity: The constancy of the speed of light puts limits on what can be seen and known. We can only know the remote past of astronomical objects that are very distant from us.
2. Uncertainty Principle: Certain pairs of physical variables, such as position and linear momentum, cannot be determined simultaneously and with arbitrary precision. The more certainty sought to determine the position of a particle, the less one knows its linear momentum.