On 14 December 2010 10:44, Jakob Voss <[log in to unmask]> wrote:

> Edward C. Zimmermann wrote:
>  On Thu, 9 Dec 2010 17:24:43 -0500, Denenberg, Ray wrote
> [...]
>> {1960,1961,1962,1963,1964,1965,1966,1967,1968,1969}
>> is a decade: 10 years.
> That's the basic fallacy. A decade "is" not the set of its years, but it
> "consists of" the set of its years. Similar a day is more than the set of
> its hours, it's just another kind of concept. For instance your wedding day
> is neither an interval, nor a set of moments. Sure you can mathematically
> define dates in such a manner, but this completely removes the human aspect
> of dates (call it cultural, sociological or anything, but *not* "purely
> logical"). Without this aspect you can just use a simple model based points,
> intervals, and precisions in time, all defined by seconds. Computers do not
> need minutes, hours, days, month, years etc. Human perceptions of dates are
> different.
>  This nicely highlights the need for conceptual clarity about what kinds
of things we are talking about. However, the approach of stating what the
"facts" are about what concepts mean is, I believe, mistaken. Concepts are
useful inasmuch as people agree on their meaning enough to have meaningful
conversations, make decisions that stick, etc. A process of consensus
building is necessary to achieve this state of agreement, and that can be
educative; pronouncements don't usually work.

"Your wedding day" is I guess a concept that we don't really want to be
dealing with directly. When I say that my wedding was on a certain day, I
mean that the actions that constituted that wedding took place within that
day. Unfortunately the concept of someone's "wedding day" is ill-defined:
people could use the phrase to mean the day on which their wedding took
place, as in "were you born on my wedding day?", or it could be used for the
set of events that constituted the wedding. We can have a set of photos
categorised "my wedding day", and it would be rather strange to see random
things from around the world that happened on that day, or photographs of a
clock, for instance. Personally, I don't think of a decade in that way, but
more just as a period of time.

Human perceptions of time-related things, and their concepts, are indeed
different, and they can change and develop. I don't think that this list
would be well employed trying to tease out all the ways in which people
think of time and events in time. I do think it is potentially useful to
give people a well-defined and richer vocabulary for expressing when things

Simon Grant
+44 7710031657