Acer asks:
What makes a chair a chair?
Answer by Craig Skinner
I assume you speak of the furniture item rather than the person in charge of a meeting or organization.
What makes a chair a chair is (as with all other things) that it matches the relevant definition, description, specification, concept or meaning, in this case:
“A seat for one person that has a back, usually four legs, and sometimes two arms”.
This definition is wide enough to include armchairs, pushchairs and wheelchairs. There will be borderline cases like deckchairs, but whether we include these is just a matter of stipulation.
End of story you might think. But no, Plato wanted more. Instead of a thing simply matching a definition or concept, for him it matched the relevant Form or Idea. All chairs in the everyday (sensible) world are imperfect instances of the perfect Form of a Chair which exists in the (intelligible) world of Forms. So what makes a chair a chair is that it is an imperfect copy, or instance, of the chair Form, it partakes of that Form. For Plato the world of Forms was more real than the everyday world which contains only imperfect copies. Notice that the Form is logically prior to the instances — if all chairs in the world were destroyed, the chair Form would still exist, only uninstantiated. And similarly with qualities, so that all red things, say, are instances of the Form of Redness, and so on.
Aristotle said the Forms were nonsense: of course, he said, the thing we’re talking about has the form of a chair, but its form exists in the chair itself, and so with all other chairs, so that if all chairs were destroyed, there would be no such form, and similarly if all red things were destroyed, no redness would exist.
I’m with Aristotle — forms and qualities exist in things, not prior to them, in rebus rather than ante rem, as the philosophers of old put it.
We’re not quite finished. Never mind whether chairs have their form intrinsically or copied from the perfect Form existing in a heavenly realm, some modern philosophers declare that chairs dont exist at all, really there exist only “particles arranged chairwise”. Why, they say, should we privilege the particles arranged “chairwise” as being a thing but not, say, the particles arranged as “my nose + the Taj Mahal + the moon”. No, they say, there are no composite objects such as chairs, otherwise we must accept crazy, gerrymandered objects like the nose-Taj Mahal-moon. Only the fundamental particles (whatever they turn out to be) exist. Awkwardly, this means you dont exist, only “particles arranged Acerwise”, but we can still talk about chairs, plants , planets and people as if they existed. Some of us (myself for one) find it hard to accept that we dont exist (but can still think, Descartes would surely consider we were joking). However, it seems to me, that if we agree particles exist and can be arranged chairwise, why not just say that matter has taken the form of a chair, or a human, or whatever, and we’re back to Aristotle’s view that a thing is a bit of prime matter taking a substantial form. As is often the case, Aristotle gets it right.
And now, worn out with not existing, I’ll settle the Craigwise-arranged particles in my favourite easychairwise particle arrangement.
Ask a Philosopher 
