Bryan asked:

Is there such thing as darkness?

Answer by Nathan Sinclair

This question reflects one of the earliest and most divisive disputes in philosophy: the existence of universals. When we conduct an inventory of the things in the universe we will find red things, tall things, just things(/people), courageous things(/people), but will we find in addition to those things also redness, tallness, justice, and courage.

Plato and Aristotle are the best known proponents of each side of this dispute, with Plato taking the side of those who believe in universals (also known as platonic forms), and Aristotle taking the side of those who deny the existence of universals.

Plato’s main argument (though he doesn’t seem to feel the need for much of one) is that we could not perceive things as having any common characteristics unless we were acquainted with the relevant universal.

Aristotle’s bets known argument is the third man argument. If two things are both men, and resemble each other in this respect only because they both instantiate the universal MAN, then what of the universal itself? It would seem that it could only resemble particular men if there was another universal (a third man) which they all instantiated. If not and the universal and the particular men can resemble each other without participating in higher universal, then surely the original individuals can resemble each other (and all be men) without the need of a universal MAN at all.

In Aristotle’s argument he relies on the assumption that universals are true of themselves: that the TALL will itslef be tall, that COURAGE will itself be courageous and so on. To modern eyes this seems ridiculous, but it was accepted by the vast majority of Ancient Greek philosophers. Still, the relationship of instantiation itself seems to need a universal (if any relationship does at all) and so some form of the argument still seems good.

In modern times the dispute turns on two problems:

On the skeptical side no one has a workable account of when two universals are the same. Merely being true of the same things isn’t enough (consider creature with a heart, and creature with a kidney, these two properties are surely different, everything with a heart has kidneys and vice versa).

On the positive side there seem to be some statements (such as “Humility is a virtue”) that seem to unavoidably rely upon the existence of universals. Those against universlas must either give a plausible re-interpretation of such claims which doesn’t rely upon universals, or abandon such statements altogether.

Putting aside the general issue of universals and looking at darkness are there any reason to suppose DARKNESS is particularly implausible?

Yes, it is both subjective and seemingly inessential to our claims about the world. Not only is darkness relative to particular visual equipment (what is dark to you ro I is not dark to an owl or a frog), and hence it would seem not a key feature of the worlds functioning. Moreover it would seem we could replace talk of DARKNESS with talk of ‘receiving insufficient light to form a visual image’. This might still leave us with a universal to deal with but it wouldn’t be DARKNESS. More generally we seem to have perfectly adequate and successful theories of the world which don’f use the term darkness at all. We could surely paraphrase claims about darkness in terms of average number of photons being received per square meter per second.

For my part I find (a modern version of) Aristotle’s argument pretty convincing, and I don’t believe in universals at all.