What is the difference between modern and classical liberalism, without using too much philosophical jargon?

Classical liberalism is the idea that “individuals are inherently good” and that they don’t need to be restricted by laws. Laws in Classical liberalism are for restricting what governments can do. e.g. If you look at the American constitution, most of the stuff in there is about preventing governments from doing stuff like banning speech or guns. People are expected to be good enough to need no restrictions on their actions.

Modern liberalism a.k.a American liberalism happened as a consequence of the world wars and related atrocities, in which people realized people can do a lot of harm to each other, and may not be inherently good. Modern liberals a.k.a American liberals still believe people are “socially” good, but cannot be trusted with monetary/economic/(self-)defense related freedoms. So they believe people need to be restricted using laws about avarice and (self-)defense.

All liberals, classical and modern, believe in the equal goodness of all people in the domains they believe people should be allowed to be free in. So modern liberals believe governments should not be allowed to make laws defining social norms. Classical liberals are also against laws defining social norms, but they are also against laws defining economic norms (e.g. what currency should be used to settle debts).

This idea of equal goodness of people in various domains, is morphing in many ways into enforcing equality in various domains. So the latest class of liberals around the world are against all (or most) social norms. e.g. They are against toilets for different genders, and just having only 2 genders, and preventing people from switching genders, and laws defining the roles of women etc.

Essentially modern liberalism has discovered a contradiction between equality and freedom while preaching equal freedoms for all. On one hand freedoms frees people to discourage and encourage certain social norms. On the other hand that leads to a inequality because some norms are preferred and some norms are discouraged.

The word liberal is probably one of the most arbitrarily used in American politics. If you include classical liberalism, then it could easily mean either “conservative”, “progressive”, or “leftist,” all different things.

“Liberalism” is of course related to the word “liberty”—it is a school of political thought that renders everything the government does subordinate to its insurance of its citizens’ freedom.

What you’re calling “modern” liberalism was originally called “social” liberalism, to distinguish it from its parent—“classical” liberalism, which in America (although less so by the year), coalesced into “conservatism.” We have no original, primordial aristocratic order to “conserve,” so really that is a misnomer: it means placing the burden of justification on the advocate of curtailing liberty to improve the country, which is to say that its better to let the country remain imperfect, than to try to make it more perfect by strengthening the state at the expense of the individual.

The divide of left and right in America differed from that of the rest of the world for that reason—after the French Revolution (when the concept of “left and right” was formed), there were liberals/republicans on the left and monarchists/conservatives on the right. The fault line was really between the idea that government can be actively created on the left, and that something resembling monarchy and aristocracy is the inevitable and natural order of the universe on the right. All the ideas of classical liberalism—property rights, consent of the governed, representation by the people, were never really disputed in America, whose regime accepts the principle of liberalism in this sense to be non-negotiable, as it is taken to represent manifestly “inalienable rights.” Old World conservatives were sometimes illiberal—which is to say liberalism wasn’t a priority for them, but they didn’t actively oppose it, as fascists like Hitler and Stalin did.

For this reason, by the 20th century, left/right, somewhat uniquely in this country, became a contest between classical liberalism on the right—which meant a more strict modeling off the founding, that the government owed you nothing other than not to make your life worse than it already was—and social liberalism on the left, which promulgated modest compromises to freedom in order to empower the state to make society more just and equitable. In principle at least, both social and classical liberals believe that what really matters first and foremost, is that the citizenry be free, and that the state be the property of the people rather than the other way around—at knowing cost to the efficiency of its apparatus.

However, many on the left calling themselves liberals are in fact actively anti-liberal, which is to say “leftist.” Leftists do not believe in consent of the governed [something quite different than a simple voting majority—a subject for a different post] or property rights, which is the opposite of liberalism. For them, what matters is equality, at the expense (as it inevitably is) of freedom. Liberalism is equality of opportunity, and leftism is equality of outcome. Social or “modern” liberalism attempts to straddle the fence, assisting in the equality of outcome without going full scale leftist and curbing people’s fundamental freedom.

It should be noted that liberal and conservative are asymmetrical categories; a “progressive” is the opposite of a conservative, and an anti-liberal/fascist is the opposite of a liberal. It is possible to be a (constitutional, i.e. “American”) “conservative liberal” then…men like John F. Kennedy and D.P. Moynihan come to mind. People tend to give the political right a monopoly on “fascism” which is just a left PR victory; a fascist is simply someone who believes the people are the property of the state and does not recognize property rights, an anti-individualist, i.e. an anti-liberal.

In essence, the difference can be explained by a disagreement on the concept of liberty. A Classical Liberal would fall in line with the negative definition of liberty. This describes the absence of obstructions to liberty and is the justification for limiting governmental interference. A modern liberal promotes positive liberty which describes a state of unhindered ability to pursue your goals and desires. Positive liberty justifies State intervention to alleviate barriers such as poverty. A classical liberal would assert that the impoverished are free because of the absence of imposed obstruction, they are free to spend their money as they please, but they choose to be prudent. A modern liberal would argue that poverty is a barrier to freedom in itself, and measure should be taken to alleviate the impoverished condition.

The consequence of this debate are:

Libertarians (and conservative republicans to a lesser degree) adhere to classic liberalism. Their stance can be determined for any issue through two questions. Primarily, does the legislation expand the power of government or open the door to future abuse of power? If the answer is yes, they would oppose; if it is no you must ask the second question. Does this legislation unnecessarily infringe on individual liberty? With the same conclusions listed above.

Democrats believe in modern liberalism (in general), which includes elements of democratic socialism and distributive justice. They generally favor a mixed economy in tandem with an expansive welfare system. Any legislation that would allow free exercise of liberty, even at the expense of others, is justified so long as all parties still have liberty in the positive sense. Some dubbed Leftists take this to a far left vision of egalitarianism. Positive liberty in their context cannot be achieved in the presence of social norms that exclude minorities in respect to gender, class, and race.