The Right tries to achieve a god-given basic state, often described with 'freedom' and 'liberty'. It thinks that the less government there is, the better. But the point here is that this is not a conclusion. It is the thesis, or even the axiom. The Right may argue that 'free markets' are useful, but that is not why the Right desires them. The god-given basic state of humanity, the cowboy on his ranch, is the goal the Right wants to achieve.
Of course, the Right is often right (no pun intended), when it comes to the benefit of little government influence, the invisible hand and the pure power a free market can unleash when it comes to generation of wealth. But this just strengthens the arguement for the god-given state. It is not the reason for this desire.
The Left tries to achieve a human-created state. A state that allows everybody to live a life free of misery. They are willing to use any means necessary to achieve this. If big government is necessary, then so be it.
Of course, the Left knows that free markets are incredibly powerful at creation of wealth, and it often argues in favor of them. But free markets are just a tool the Left begrudgingly uses to increase the size of the cake it ultimately wants to redistribute.
Both are extreme ideologies, of course. The Failure of the Right often is that it doesn't want to create a society anybody actually would want to live in, but rather a visionary god-given state that in its truest form is probably not desirable for most people. The Failure of the Left is that it overestimates the human ability to govern itself and ignores harmful side effects of laws and centralization.
In todays NYT I found this:
We could save billions in health care costs and make healthier food cheaper if we taxed nutritionally weak foods.
Now, this proposal is obviously on the left hand side of the political spectrum. The Right will disagree with this, and it will give all kinds of arguments. But the real reason the Right disagrees is that such a tax would remove the country from the god-given state.
The Left, on the other hand, welcomes such a proposal. It is always looking for easy ways to make life better. There might be negative side effects of such a new tax, but it's something the Left would have a look at before it would discard the proposal.