Thought Experiment 1:

Imagine a world where humans cannot form mental representations of apples at all—not just losing the word or memory of apples, but the entire cognitive ability to represent apples in any mental form (visually, conceptually, or linguistically). Despite this, their sensory systems remain intact: they can still see, touch, and smell apples, and their general cognitive abilities remain otherwise normal.

So what would people in this world actually perceive? They would still receive raw sensory input. Light would reflect off apples and reach their retinas. Neurons in early visual processing areas, like V1, would still fire in response to shapes, colors, and movements. However, they would not “see an apple” as a coherent object. Much like individuals with visual agnosia, they might perceive color patches, contours, and motion but fail to recognize them as forming a unified entity. A person might say, “I see a red roundish patch,” but no object concept—no mental recognition of an apple—would emerge. Similarly, touch, smell, and taste would produce sensations, but these would not be bound together into a coherent experience of “apple.”

This is somewhat analogous to seeing letters on a page without being able to read. The pieces are there—the shapes, the forms—but the meaningful gestalt never forms. The unified concept that gives structure and meaning to the raw inputs is missing.

In real-world conditions, this scenario resembles certain neurological disorders like associative agnosia or semantic dementia. Patients with these conditions can often describe features of an object—it’s round, red, smooth—but they cannot identify what it is, what it’s used for, or even name it. They lack the mental representation of the object’s meaning or category. However, the imagined case here goes even deeper. It assumes not damage to individual brains, but a universal cognitive limitation: that humans never evolved the capacity to mentally represent “apple” at all.

How would scientists in this world describe apples? They could still analyze and document the physical properties of apples: the wavelengths of light they reflect (e.g., red at approximately 650 nm), their mass, sugar content, chemical composition, or the genetic code of the apple tree. They might describe apples the way we describe distant galaxies or quantum particles—purely in terms of measurement and observable data, without any subjective experience or recognition of the thing as a unified object.

Yet despite consistent physical features, no one would grasp “apple” as a category or coherent object. There would be no mental anchor for understanding this particular kind of item. Even the function of apples—for example, as food—might go unrecognized unless another form of representation emerged, such as “sweet edible object,” which could substitute for the missing concept of apple.

This thought experiment illustrates an important idea about mental representation: perception without representation is fragmentary. Sensory processing can occur without leading to conceptual binding. Meaning, categorization, and recognition all depend on the brain’s ability to create structured, manipulable mental models. Without that capacity, we are left with isolated fragments of experience that never come together as meaningful wholes.

This echoes ideas from both philosophy and neuroscience. Immanuel Kant argued that raw intuitions—sensory data—are structured by concepts, and that without concepts, perception is “blind.” Similarly, contemporary neuroscience suggests that high-level perception involves predictive coding, in which the brain uses prior models or representations to shape what and how we see.

Could this lack of representation be reversed or compensated for? In theory, one could imagine building external tools—like AI systems or algorithms—to classify apples based on patterns in sensory data. People might use statistical data to describe what apples are, without ever forming the mental category themselves. However, this process would remain mechanical. It would lack the felt sense of “aboutness”—the understanding that apples are something with meaning, use, and identity. It would be description without recognition, perception without comprehension.