How "big" is a thought? Nicholson Baker thinks "most are about three feet tall, with the level of complexity of a lawnmower engine, or a cigarette lighter, or those tubes of toothpaste that, by mingling several hidden pastes and gels, create a pleasantly striped product" Perhaps we'd better ask, what makes for a "unit" of thought? Or still better: is there a unit of thought? Is it a concept or a word, or a sentence, a paragraph or a document?
Locke would have had no problem saying "yes." It's an idea—most likely a complex idea. In other words, it's something expressed by a word. Others, like Kant, have argued that a thought requires a proposition, judgment or sentence (and that a concept is something like an abbreviated thought).
Ranganathan, inventor of faceted systems and the five laws of library science thought that a "document" was an "embodied micro thought" on paper "or other material, fit for physical handling, transport across space, and preservation through time."
I myself like Collingwood's idea that "the true 'unit of thought'" is not "the proposition but something more complex in which the proposition served as answer to a question." So for him a thought always presupposes a question and represents an answer to such a question. I would add that such answers usually require more than a sentence, and that at least a paragraph is necessary for anything that approaches "the level of complexity of a lawnmower engine." My paragraphs usually are between 200 and 500 words long.
If you need more than a paragraph to answer a question, you probably need more than one thought for the answer.
Whether thoughts come in chunks or objective units of meaning, like the seven (or ten) digits that make up a telephone number and knowledge has a granular structure is an entirely different question. I am skeptical about our ability to identify the beginnings and ends of particular thoughts. That skepticism does not imply, however, that we should not try to formulate one thought at a time.
1. If a "unit of thought" presupposes a question, it presupposes other units of thought, whether they be clearly expressed or not.
2. The paragraphs in this blog are therefore not quite representative.