People have a series of rationalizations. People say for example that science 
  and technology have their own logic, that they are in fact autonomous. This 
  particular rationalization is profoundly false. It is not true that science 
  marches on in defiance of human will, independent of human will, that just is 
  not the case. But it is comfortable, as I said: it leads to the position that 
  "if I don't do it, someone else will." 
  
  Of course if one takes that as an ethical principle then obviously it can serve 
  as a license to do anything at all. "People will be murdered; if I don't do it, 
  someone else will." "Women will be raped; if I don't do it, someone else will." 
  That is just a license for violence. 
  
  Other people say, and I think this is a widely used rationalization, that 
  fundamentally the tools we work on are "mere" tools; This means that whether 
  they get use for good or evil depends on the person who ultimately buys them 
  and so on. 
  
  There's nothing bad about working in computer vision, for example. Computer 
  vision may very well some day be used to heal people who would otherwise die. 
  Of course, it could also be used to guide missiles, cruise missiles for 
  example, to their destination, and all that. You see, the technology itself is 
  neutral and value-free and it just depends how one uses it. And besides -- 
  consistent with that -- we can't know, we scientists cannot know how it is 
  going to be used. So therefore we have no responsibility. 
  
  Well, that is false. It is true that a computer, for example, can be used for 
  good or evil. It is true that a helicopter can be used as a gunship and it can 
  also be used to rescue people from a mountain pass. And if the question arises 
  of how a specific device is going to be used, in what I call an abstract ideal 
  society, then one might very well say one cannot know. 
  
  But we live in a concrete society, [and] with concrete social and historical 
  circumstances and political realities in this society, it is perfectly obvious 
  that when something like a computer is invented, then it is going to be adopted 
  will be for military purposes. It follows from the concrete realities in which 
  we live, it does not follow from pure logic. But we're not living in an 
  abstract society, we're living in the society in which we in fact live. 
  
  If you look at the enormous fruits of human genius that mankind has developed 
  in the last 50 years, atomic energy and rocketry and flying to the moon and 
  coherent light, and it goes on and on and on -- and then it turns out that 
  every one of these triumphs is used primarily in military terms. So it is not 
  reasonable for a scientist or technologist to insist that he or she does not 
  know -- or cannot know -- how it is going to be used.

-- Joseph Weizenbaum