You Can't Get an 'Ought' From an 'Is'

Dialogues #43

“A barrier to entailment is something that gets in the way of there being valid arguments from premises of one kind to

conclusions of another. Hume’s Law is an example; it says that valid arguments cannot have descriptive premises and normative conclusions or, in slogan form:

you can’t get an ought from an is...” - Dr. Gillian Russell

🚨Episode 14 of the podcast is out! 🚨

Gillian Russell is the kind of philosopher who has published papers on the ethics of martial arts, presented a paper in Kuwait on virtual reality, spent decades working on the philosophy of language and logic, and writes cutting edge philosophy where you actually enjoy reading her work.

That's rare.

I first met Gillian through a workshop group I ran as a PhD student at Texas A&M. We were in the thick of the quarantine years, and I would contact philosophers all over the world to see if they were interested in presenting work in progress virtually to a few grad students and to other professors from around the world.

It gave scholars a chance to think through and stress test unfinished work, by getting feedback and comments that they could later use to polish a paper or book.

I love philosophy of language and philosophy of logic, and there aren't many philosophers like Gillian who are both technically, logically proficient and conversationally pleasant. So in this episode we get into logic and language, but on the way you will hear about why she was interested in philosophy in the first place.

She also made a name for herself early on by working on the ethics and epistemological issues within martial arts (you can read an abstract of one of her papers here, full PDF at the link).

We also get into her recent book, Barriers to Entailment: Hume's Law and Other Limits on Logical Consequence, which as I mention in the episode, is a landmark work in philosophy, uniting logic, ethics, metaphysics, philosophy of time, and philosophy of language.

Hume's Law is one example of a barrier, but she also addresses four others:

The particular/universal barrier: you can't get a universal claim from a particular claim
The past/future barrier: you can't get a claim about the future from a claim about the past
The is/must barrier: you can't get a claim about how things must be from a claim about how things are
The indexical barrier: you can't get an indexical claim ("I am typing") from a claim that is not indexical ("Jared is typing")

She addresses each barrier informally through ordinary language, but she also looks at the formal similarities between each barrier, using the most suitable logic for each claim: tense logic, modal logic, indexical logic, and deontic logic.

We don't get that technical in the episode, but if you're interested in those details, the book gives you that option.

It was a fun episode. Check it out.

Until next time,

Jared

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