Why do empiricists disagree about whether people directly perceive physical objects?

Empiricists disagree about whether people directly perceive physical objects primarily due to conflicting interpretations of how sensory experience relates to the external world. This debate centers on the nature of perception and the challenge of accounting for perceptual anomalies, such as illusions or visual distortions.123

The disagreement generally falls into two main perspectives:

• Sense-Data Theory (Indirect Perception): Many empiricists argue that we are directly aware only of "sense-data"—private, mind-dependent mental images or sensations—rather than the physical objects themselves. Proponents, including figures like John Locke, suggest that these sense-data represent external objects, though this creates the "egocentric predicament": if we only perceive our own mental representations, we cannot be certain they accurately correspond to an independent physical reality.234
• Direct Realism: Other empiricists reject the necessity of sense-data, arguing that we can directly perceive physical objects or their surfaces. Direct realists contend that there is no need to infer the existence of objects from mental intermediaries, as our sensory systems allow us to observe the physical world immediately.21

These conflicting views persist because neither has fully resolved the difficulty of explaining how we gain certain knowledge of an external world while acknowledging the subjective, and sometimes deceptive, nature of human sensation.23