They are based on a few key intuitions. The first is that scientific knowledge is not communicated (only) via isolated scientific papers, linked to each other via citations. Rather, it is exists in different kinds (data, experiments, ideas,...), it is communicated in different forms (papers, talks, blogs), it evolves almost continuously over time, and it is connected in a knowledge network (papers describe experiments that are built over datasets, all based on ideas inspired from other talks or blogs). 

The second intuition is that the network which would be so useful to navigate in the sea of scientific knowledge is not objective, but subjective. Whether a paper is inspired from another, or whether a person contributed to a paper may be proven facts or may be opinions, which may also take different forms. The third intuition is that we can use the power of the community as editors to help us select knowledge among a sea of information, rather than leaving this role to a selected few. The fourth intuition is that editors and the community of readers can create knowledge. This is a huge potential that is currently untapped for various social and technical reasons, but that can be used to service the scientific community. Finally, LJ enforce diversity in search, correcting the problem that is generated by having too much content of the kind we like, or that we are used to, thereby restricting our search breadth. You can begin to see things at work at liquidjournal.org or read our paper on the topic.