Question:

How can we know the date of an event or writing from thousands of years
ago if the date was not recorded at that time? For example, someone may
say, “this was written around 58 AD”. How can we know that for sure? Or
even when someone says, “the book of ____ was written in 16th Century
BC”. How can we know that for sure?

Answer:

There are a number of ways to estimate the date of ancient events. Some
we know quite exactly, others we only know approximately. One example of
an event we know quite well is the Santorini eruption. This was a massive
volcanic eruption on the island of Santorine in the Aegean Sea. The
eruption happened in about 1650 BC. This produced a massive tidal wave
and layers of ash across the entire earth. It also affected climate for a
few years afterward. An arial photograph of the caldera of this eruption
is below.

Satellite image of Santorini. Clockwise from center: Nea Kameni; Palea
Kameni; Aspronisi; Therasia; Thera

We know the date of this eruption within about 20 years or so from a
variety of data. One is from the ice cap in Greenland. One can count
backward in time by looking at the anual layers of ice which have been
deposited in Greenland. The ash from this massive explosion produced
obvious evidence in the Greenland ice cap. In addition, we have carbon
dating from remaining settlements on Santorini which were obviously
destroyed at that time. Archaeologists are fairly conficent that it was
this massive explosion which virtually destroyed the Minoan civilization
on Crete and many of the Greek islands at that time.

The reason I mention this is that some events in the Near East can be
dated with respect to this event. In addition, the Babylonians and
Assyrians recorded solar eclipses, tying events in their history to these
events. Scientists can calculate the occurrances of such eclipses several
thousand years into the past. From this kind of data we can obtain some
dates to within one year starting several hundred years BC. One such
event occurred on July 15, 763 BC. There are remaining difficulties
justifying the Assyrian, Babylonian and Egyptian chronologies, but we have
sufficient data that we can calculate dates to within a year or so for
many of the most significant events in the Near East after this date.

There are other methods for calculating the dates for certain events.
Some of these are more approximate. For example, Carbon-14 radiometric
dating is fairly accurate. Besides, we can cross-reference C-14 ages with
things such as the solar eclipse in 763 BC and the Santorini eruption.
For over two thousand years ago, the size of the uncertaintly grows
significantly for C-14 dates. There is some doubt about the assumption
that the carbon 14 content in the atmosphere is constant. There are also
issues of cross-contamination and other corrections. Given all this, one
can say that carbon 14 ages are good to perhaps 5-10% back to 2-3000 BC
and perhaps even more uncertain for earlier dates. When we read that a
settlement in Syria was established in 8500 BC using C-14 and pottery
evidence, it might be good to assume it is between 8000 and 9000 BC and,
conservatively, between 7500 and 9500 BC. Remember that there are a
number of cross-checking kinds of evidence which can be used, such as
pottery style, metal use and many others. The determining of the age of
ancient finds in obviously an inexact science. You should take dates with
a grain of salt, but scientists do have good enough technologies available
to them that if you allow for a sufficient error in the dates you read
about, in most cases, the dates quoted by scientists and archaeologists
will be reasonably good.

You ask a separate but related question. What about the date a particular
book was written? This is a more difficult question than establishing the
date when king Hezekiah lived. You will find this discussed in various
articles and answered questions at the web site. In every case we do not
have the original biblical book. For this reason, archaeologists and
scientific data are not particularly helpful to determine the date at
which a book was written. Scholars must use evidence internal to the
books themselves to determine the date at which they were written. For
example, we can estimate the date when the book of Mark or Acts was
written to within less than ten years from what we know about the author,
when the books were quoted by others, the historical context and so
forth. You can be fairly confident that Mark was written about AD 65. It
may have been written as early as. Almost certainly it was written before
AD 70 as it was written before the destruction of Jerusalem. For Old
Testament books, the date of authorship is more difficult to establish.
If we can assume that Isaiah wrote the book of Isaiah (which, by the way,
is very difficult to prove) then we know Isaiah’s carreer spanned from
about 740 BC to about 690 BC, so we know the date this book was written.
When was Genesis written? This is far more difficult to establish.
Multiple arguments are advanced with regard to the age of the book from
Hebrew style used to the accuracy (or lack thereof) of cultural and
historical references in the book. The bottom line is that we do not know
when Genesis was written. It may have existed in parts in oral form for
hundreds or even thousands of years, but only put to writing some time as
late as 800 or 900 BC. We simply do not know.

Bottom line, if you want to know how confident you should be about a date
quoted for an event or a book you will have to do some of your own
research. In doing so, keep in mind that some scholars assume that the
Bible is not inspired by God. They have agendas which cause them to want
to move the dates as late as possible. You should watch for their
biases. Of course, believers have their biases as well, which is why you
should look at the evidence and the arguments, not the conclusions of
those you read.

John Oakes, PhD