I can define a liberal in a lot less space than that article - in a word, 'opposite' or 'wrong'!
Liberals aren't for liberty, but rather control / more laws. 'Progressives' are really digressing mankind. 'For the middle' - hell no - they want to create haves & have nots more than any other group, with them on top, of course. For science - maybe if its poor science that only serves to agree with their next effort to make them lots of money ( ie. 'carbon credits' ). Religious freedom - nope - they want to suppress religion. Equal rights - nope - special rights for the 2%'ers / outliers of normal society.
Whatever makes sense, whatever they call themselves that insinuates something good, it is always the opposite.