What does "they alone" mean? "the community alone"?

Context:

A paradigm shift (or revolutionary science) is, according to http://en.wikipedia.org/wiki/Thomas_Samuel_Kuhn, in his influential book http://en.wikipedia.org/wiki/The_Structure_of_Scientific_Revolutions (1962), a change in the basic assumptions, or http://en.wikipedia.org/wiki/Paradigm, within the ruling http://en.wikipedia.org/wiki/Theory of http://en.wikipedia.org/wiki/Science. It is in contrast to his idea of http://en.wikipedia.org/wiki/Normal_science. According to Kuhn, "A http://en.wikipedia.org/wiki/Paradigm is what members of a scientific community, and they alone, share" (The Essential Tension, 1977). Unlike a normal scientist, Kuhn held, "a student in the http://en.wikipedia.org/wiki/Humanities has constantly before him a number of competing and incommensurable solutions to these problems, solutions that he must ultimately examine for himself" (The Structure of Scientific Revolutions).