Where Does LLM Grounding Come From? The Humans Who Wrote the Training Data
A short explainer on inherited grounding
The Objection
“LLMs aren’t grounded in physical reality. They’ve never touched anything, seen anything, experienced anything. They just shuffle symbols.”
This objection has intuitive force. An LLM has never lifted a heavy box or burned its finger or felt rain on its face. How can it understand “heavy” or “hot” or “wet”?
The Answer: Inherited Grounding
Consider who wrote the training corpus.
Not disembodied minds. Humans. Beings with bodies, living in a physical world, subject to gravity and temperature and weather. When those humans chose their words, their choices were constrained by physical reality.
“Heavy” means what it means because humans have lifted things. “Hot” means what it means because humans have touched flames. “Stumbled” appears in sentences describing loss of balance because humans have bodies that lose balance in predictable ways.
The physical world shapes human experience. Human experience shapes human language. An LLM learning the statistical structure of human language learns, thereby, the structure of human physical experience.
This is inherited grounding. The LLM hasn’t touched the world directly. But it inherits the grounding of the humans who did and then wrote about it.
An Analogy
Imagine a historian who has never visited ancient Rome. They’ve read thousands of documents written by people who lived there: letters, records, accounts, descriptions. Does the historian understand Rome?
Not the way a citizen did. They’ve never walked the streets or smelled the markets or felt the Mediterranean heat. But they’ve integrated information from people who did. Their understanding is mediated but real.
Now imagine the historian has read everything written by everyone who ever visited Rome. Every letter, every diary, every account, in every language, across centuries. Their understanding would be different from direct experience, but it would be extensive and structurally accurate.
That’s closer to what LLMs have: not direct experience, but comprehensive access to the descriptions generated by beings who had direct experience.
The Important Caveat
Inherited grounding is real but partial.
Humans didn’t just perceive the world. They acted on it. They tested their models through intervention. They learned from consequences. “Fire is hot” was confirmed by touching fire; “heavy things fall” was confirmed by dropping them.
That agentive loop isn’t directly in the corpus. The LLM inherits what humans observed and described, not the trial-and-error process by which they verified it.
This explains a puzzle about LLMs: they can reason accurately about physical concepts they’ve never experienced, but they can also confidently generate plausible-sounding nonsense. They have the observations without the error-correction that comes from action.
Inherited perceptual grounding: yes. Inherited agentive grounding: no, or at least much weaker.
Why This Matters
The grounding objection assumes LLMs are working with ungrounded symbols, floating free of reality. But the symbols came from somewhere. They were generated by grounded beings whose word choices were constrained by the world.
The training corpus isn’t a closed dictionary, words defined by other words in an infinite loop. It’s an artifact of human engagement with physical reality. The grounding is baked into the data.
Critics who say “but it’s never touched anything” are right about direct grounding. But they’re ignoring inherited grounding: the physical reality that shaped the language that shaped the model.
The LLM’s world-model was built by borrowing from billions of humans who did touch things, see things, experience things, and then wrote about what they learned.
That’s not the same as direct experience. But it’s not nothing, either.
This explainer accompanies “Functional Perceptual Grounding: LLMs Don’t Just Process Language. They Perceive It.”