The idea behind the concept of 'technology', and of 'technical progress' as   
a source of growth is simple, isn't it? Many kinds of scientific and   
technical knowledge are, at least in principle, public goods - once   
something is discovered, it can be used by anyone - and they can be thought   
of as growing in a cumulative way - new discoveries are added to what was   
known before. We are better off than our ancestors primarily because we   
know more.  
  
Economically valuable knowledge unavailable to past generations becomes   
readily available in reference works, textbooks, and so on. Equipment   
embodying complex techniques can be bought in the market (computers,   
software, vehicles, etc.) and people with experience and training can be   
hired as employees or consultants. There is an element of truth to the idea   
of a state of technology which changes over time but is available to all at   
a given date.  
  
Some (many) forms of economic knowledge, such as Pat Gunnings 'knowledge of   
buying and selling opportunities', don't fit this pattern and aren't what   
we usually mean by 'technology' - which isn't to say they are not important.  
  
On closer examination, of course, the simple picture given above dissolves   
- usable technical knowledge is a mixture of 'public' elements, available   
to all, with 'private' skills and knowledge peculiar to individuals and   
organizations, etc. The simple picture still seems to me to have its uses,   
though.  
  
Tony Brewer