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I recently came across the following sentence in some documentation for a programming API:

Angular animations are defined as logical states and transitions between states.

https://angular.io/docs/ts/latest/guide/animations.html

What is the definition of "logical" in this context? I have seen the word "logical" used as an adjective this way before, and I sort of gather from the context that using "logical" like this is meant to describe the noun that follows as an abstraction. For example, the "states" in the example sentence are just conceptual states. Is this correct? Is there a definition out there that clarifies this?

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  • Presumably entities which have a logical existence, but no practical one. How interesting.
    – WS2
    Commented Jan 10, 2017 at 22:44
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    Who knows, without further context. Perhaps they mean Boolean states, i.e., states that have either of the two logic (truth) values true and false. Provide more context, if you want better help.
    – Drew
    Commented Jan 10, 2017 at 22:45
  • en.wikipedia.org/wiki/State_%28computer_science%29
    – michael.hor257k
    Commented Jan 10, 2017 at 22:56

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This is a highly technical usage dating from the early days of discrete circuitry.

All circuits have some physical quantity -- typically voltage -- that represent a binary state. For example, +5 volts might mean "true", while 0 volts meant "false".

In this situation, its voltage was referred to as "physical state" and the binary value it meant as its "logical state". In this sense, logical means "abstract".

As computers get more sophisticated, the hierarchy of abstraction gets more elaborate. In the case you cited, there is a memory address somewhere set to 0000, 0001, or 0002, which the animation software interprets as "Paused", "Running", and "Finished". The latter possibilities describe the software's logical state.

For parallelism, the numerical values should be the "physical state", but in fact, no one ever says that -- perhaps because the numbers are just the logical state of a sequence of binary digits, and those binary digits are the logical state of potential energy stored in microscopic capacitors deep in the computer.

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  • The context here is animations - that's very far from "the early days of discrete circuitry."
    – michael.hor257k
    Commented Jan 10, 2017 at 23:44
  • @michael.hor257k -- language is a coded social history. Look at the etymology of handicapped, sex, or schist for examples. The dawn of electronics is not "very far" in the past.
    – Michael Lorton
    Commented Jan 11, 2017 at 0:36
  • @michael.hor257k The main point is that logical refers to the abstraction or concept that maps to something physical. The distinction between logical and physical is made throughout electronics and in computer science— people of a certain age may remember partitioning one physical hard drive into logical C and D drives. Nowadays, we have enough computing power for abstractions of abstractions (virtualizations), and thus the more marketing-friendly term virtual may be more familiar to the end user.
    – choster
    Commented Jan 11, 2017 at 2:43

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