The Problems of Ontology

Never mind "What's Stuff?", what's a knife?

Easy peasy. A knife is... er... a sharp edged, hand-held tool for cutting.

Or, to quote the OED (hope this counts as Fair Use) "A cutting instrument, consisting of a blade with a sharpened longitudinal edge fixed in a handle, either rigidly as in a table-, carving, or sheath-knife, or with a joint as in a pocket- or clasp-knife..."

Do you see it? The wood?

The essential observation to make is that a knife is defined in no small part by what it does, how it is used, and not by intrinsic, objective characteristics: the purpose or application of a thing would seem to be a defining characteristic. I could sharpen the edge of a credit card and use it as a knife, but would it be a knife? Maybe. Certainly if I bind it soundly to a good, strong carrot.

What about a knife that has lost it's handle? Is it still a knife - a handle-less knife? What about a knife that has lost it's blade? How can I even refer to a blade-less knife?

[I pick these examples for several reasons, one of which is that I do recall a Radio 1 DJ running a phone-in for words defining things that don't exist (strangely high-brow for Radio 1, but it was a long time ago), and - although I can't remember the word that was coined - I do remember a definition: "A blade-less knife without a handle."]

The Ontology of Everything must take such things into account.

The military like(s) to talk about Capability - we have a Rapid Response Capability, a Persistent ISTAR Capability, a Nuclear Deterrence Capability, u.s.w. - but, alas, one cannot have (or not have) an unqualified Capability.

What one can have are degrees (qualitative or quantitative) of Capability, where Capability becomes the ability to achieve a certain specified result (or perhaps class of results) under specified circumstances (e.g. environmental conditions, available resources, etc.).

An example I have used before involves the comparison of a Knife and a Screwdriver in terms of their "Capabilities".

A (good) knife is good for cutting and probably stabbing too. A screwdriver is not only good for tightening or removing screws, it too is probably a good stabber. And for certain types of screw (usually small slot headed screws) a knife can be an acceptable screwdriver.

So, what do you need for a Stabbing Capability? There are (at least) two choices. And what differences between a knife and a screwdriver should or could be used to separate them in an ontology... or what similarities would put them in the same category?

It would appear that an Ontology of Everything would be hard to keep orthogonal.

How can one construct an ontology of Things when Thingness is so fuzzy?

Ha!

Not telling (yet) But here's a clue: don't.