Argumentation involves formally representing chains of reasoning and evidence, often via diagrams.

Category theory handles categorisation and groups.

Chunking involves mentally lumping a group of separate activities or concepts into a single unit.

Compiled skills are skills so highly practised that they can be performed without thinking about them.

Connectionism is a way of representing knowledge as a set of connected links, rather than as a modular structure.

Craft skills are informal skills normally viewed as too low-level to merit being formally taught.

Design rationale is a way of recording the reasons for each decision during design of a product or system.

Expressive behaviour is behaviour which shows what sort of person you are (c.f. instrumental behaviour).

Expressive behaviour: A worked example. This article works through the example of a doomsday group.

Facet theory involves being able to categorise the same topic in more than one way (e.g. via several hierarchies).

Graph theory is a body of mathematics that deals with networks. It's invaluable for representing knowledge.

Game theory involves formally modelling the outcomes from interactions between different strategies.

Instrumental behaviour is about getting something done, as opposed to expressive behaviour (qv).

Instrumental behaviour: A worked example. Instrumental aspects of a doomsday group's behaviour.

Liminality involves places of transition, e.g. between a sacred space and a normal one.

The mathematics of desire is an informal description for regularities in human aesthetic preferences.

Necker shifts occur when you realise that there's a completely different way of viewing the same object or situation.

The Pareto principle is another name for the 80:20 principle, where 80% of one thing comes from 20% of another.

Passive ignorance vs active ignorance is about happening not to know something, versus not wanting to believe it.

Pixy dust is an informal name for indicators of excellence that don't require much space.

Prototype theory is a form of category theory based on the idea of varying degrees of category membership.

Range of convenience refers to the contexts in which a term can meaningfully be applied.

Schema theory is about mental templates, such as the schema for a sports car as opposed to a town car.

Script theory is a form of schema theory that deals with mental templates for events and activities.

Significant absence is when the absence of something is significant (e.g. the dog that didn't bark in the night).

Sociotechnical approaches are about the ways that technologies and human behaviours affect each other.

Spare capacity aka slack is present when a system is not using all of its resources; it's useful during unexpected demand.

Subsystem optimisation vs system optimisation involves what's good for the part versus what's good for the whole.

Systems theory is a formal approach describing the behaviour of systems; this often produces surprising effects.

The uncanny valley occurs when a person or object is neither quite one thing nor another (c.f. liminality).