If your morning commute involves crowded public transportation, you definitely want to find yourself standing next to someone who is saying something like, “I know he’s stabbed people, but has he ever killed one?” . It’s of course best to enjoy moments like this in the wild, but I am not above patrolling Overheard in London for its little gems (“Shall I give you a ring when my penguins are available?”), or, on an especially desperate day, going all the way back to the London-Lund Corpus of Spoken English, a treasury of oddly informative conversations (many secretly recorded) from the 1960s and 1970s. Speaker 1: “When I worked on the railways these many years ago, I was working the claims department, at Pretona Station Warmington as office boy for a short time, and one noticed that the tremendous number of claims against the railway companies were people whose fingers had been caught in doors as the porters had slammed them.” Speaker 2: “Really. Oh my goodness.” (Speaker 1 then reports that the railway found it cheaper to pay claims for lost fingers than to install safety trim on the doors.)
If you ever need a good cover story for your eavesdropping, you are welcome to use mine: as an epistemologist, I study the line that divides knowing from merely thinking that something is the case, a line we are constantly marking in everyday conversation. There it was, in the first quotation: “I know he’s stabbed people.” How, exactly was this known, one wonders, and why was knowledge of this fact reported? There’s no shortage of data: knowledge, as it turns out, is reported heavily. In spoken English (as measured most authoritatively, by the 450-million-word Corpus of Contemporary American English), ‘know’ and ‘think’ figure as the sixth and seventh most commonly used verbs, muscling out what might seem to be more obvious contenders like ‘get’ and ‘make’. Spoken English is deeply invested in knowing, easily outshining other genres on this score. In academic writing, for example, ‘know’ and ‘think’ are only the 17th and 22nd-most popular verbs, well behind the scholar’s pallid friends ‘should’ and ‘could’. To be fair, some of the conversational traffic in ‘know’ is coming from fixed phrases, like — you know — invitations to conversational partners to make some inference, or — I know — indications that you are accepting what conversational partners are saying. But even after we strip out those formulaic uses, the database’s randomly sampled conversations remain thickly larded with genuine references to knowing and thinking. Meanwhile, similar results are found in the 100-million-word British National Corpus; this is not just an American thing.
It’s perhaps a basic human thing: conversations naturally slide towards the social. When we are not using language to do something artificial (like academic writing), we relate topics to ourselves. Field research in English pubs, cafeterias, and trains convinced British psychologist Robin Dunbar that most of our casual conversation time is taken up with ‘social topics’: personal relationships, personal experiences, and social plans. Anthropologist John Haviland apparently found similar patterns among the Zinacantan people in the remote highlands of Mexico. We talk about what people think, like, and want, constantly linking conversational topics back to human perspectives and feelings.
There’s an extreme philosophical theory about this tendency, advanced in Ancient Greece by Protagoras, and in our day by the best-known living American philosopher, Kanye West. Protagoras’s ideas reach us only in fragments transmitted through the reports of others, so I’ll give you Kanye’s formulation, transmitted through Twitter: “Feelings are the only facts”. Against the notion that the realm of the subjective is unreal, this theory maintains that reality can never be anything other than subjective. Here (as elsewhere) Kanye goes too far. The mental state verbs we use to link conversational topics back to humanity fall into two families, with interestingly different levels of subjectivity, divided along a line which has to do with the status of claims as fact. The first family is labeled factive, and includes such expressions as realizes, notices, is aware that, and sees that; the mother of all factive verbs is knows (and according to Oxford philosopher Timothy Williamson, knowledge is what unites the whole factive family). Non–factives make up the second family, whose members include thinks, suspects, believes and is sure. Factive verbs, rather predictably, properly attach themselves only to facts: you can know that Jack has stabbed someone only if he really has. Non-factive verbs are less informative: Jane might think that Edwin is following her even if he isn’t. In saying that Jane suspects Edwin has been stabbing people, I leave it an open question whether her suspicions are right: I report her feelings while remaining neutral on the relevant facts. Even when they mark strong degrees of subjective conviction — “Edwin is sure that Jane likes him” — non-factive expressions do not, unfortunately for Edwin in this case, necessarily attach themselves to facts. Feelings and facts can come apart.
Factives like ‘know’, meanwhile, allow us to report facts and feelings together at a single stroke. If I say that Lucy knows that the train is delayed, I’m simultaneously sharing news about the train and about Lucy’s attitude. Sometimes we use factives to reveal our attitudes to facts already known to the audience (“I know what you did last summer”), but most conversational uses of factives are bringing fresh facts into the picture. That last finding is from the work of linguist Jennifer Spenader, whose analysis of the dialogue about railway claims pulled me into the London-Lund Corpus in the first place (my goodness, so many fresh facts with those factives). Spenader and I both struggle with some deep theoretical problems about the line between knowing and thinking, but it nevertheless remains a line whose basic significance can be felt instinctively and without special training, even in casual conversation. No, wait, we have more than a feeling for this. We know something about it.