One of the principal lessons that should be taught in courses dealing with politics and public policy is the persistence of uncertainty.People who insist on telling us what will be, or what will not be, have a lot to learn.Many who claim to be predicting are telling us what they want to happen, or--alternatively--telling us that their enemies currently in power are bound to make things worse.The reality is that there are many things capable of influencing who wins an election, which party or sub-party faction will have the upper hand in the legislature, what will be the result of a law, regulation, key personnel appointment, or budget allocation.The 2016 presidential race seemed rather certain some time ago. It'd be Hillary against Jeb. Now Donald is a major player, but still a long way from the nomination. Hillary is slipping. Her e-mail problem may have legs. Polls show that lots of people have doubts about her and about Donald. Jeb is somewhere down in a crowded list of Republicans. It looks like the Governor of Wisconsin, who had a bit of time in the limelight, can go back to worrying about the price of milk.Another flap that became last week's news was the animosity between Barack and Bibi, heated up by Iran and that speech in Congress. The latest news is that they'll be meeting in November, and most likely talking about American money and equipment to help Israel with Iran and the terrorists it supports. The President and Congressional Democrats are also talking about sanctions against Iran linked to its support of terror rather than its nuclear program.We read that different groups of American Jews are furious at one another over their support or opposition to the Iran deal and Bibi's speech..That may only say that political activists are more likely to be excitable than senior politicians, thinking that any flap between their partisan heroes is serious enmity that they must personalize.National leaders depersonalize a lot for the sake of interests they see themselves as having to serve. One week's crisis may go away in the presence of underlying concerns, or the details of this week's crisis.Iran was last month.Now it's a wave of refugees.The initial welcoming by politicians posing as humanitarians has turned into a renewal of border controls and the turning back of those not wanted, something that Western Europeans had abandoned years ago under the heading of open borders.Every government has an annual tussle, and often more than once a year about the budget. It is the key element in the formulation and implementation of public policy. Presumably, you get what you pay for. But not always. Money may be key, but there are numerous other factors that affect what we get from government. Laws and regulations (which change more frequently than laws) determine who gets what. Individual bureaucrats have some degree of discretion, and we know that they may discriminate on the basis of a client's ethnicity, race, address, demeanor, age, sex, or sexual preference. Some government agencies are "savers," in the hands of officials who seek to parcel out their services miserly. Others are in the hands of excess spenders, who pride themselves in reaching zero, and having to demand more funds in order to finish the year. Events in the economy, natural disasters, and international crises come without warning, and press senior officials to find money for what has become important.Political fashions change. The status of ethnic minorities, women, the handicapped, gays, lesbians, transgenders may rise or fall in response to campaigns in the media, the passion of a leading politician, or an especially vicious attack on an individual.Political actors are not passive. There's always a lot on the agenda. We know that the most pressing influence on what government does is what it did last year. Things don't change all that much, and usually a bit at a time, i.e., incrementally. And the greatest general influence on the overall level of public services is the level of a nation's economy. No surprise that the residents of rich countries get more than those of poor countries.This is the general picture. Someone wanting to know what is likely to happen should realize that there are occasional surprises. Policy changes in ways that bear no resemblance to what had been, or the availability of resources.What's not wise is demonstrating certainty about what'll happen with respect to particular issues. Will Europe will fold or hold firm with respect to the flood of migrants? Which of several dozen militias in Syria will emerge with substantial territory and how long it will hold what it captures? Which of Mahmoud Abbas' frequent threats will actually be implemented, and what, if that happens, will be the result? How long will the American Jewish left remain upset with Israel? And will it make any difference on anything other than the temperament of those Jews who express themselves?Our latest headlines deal with an increase in stone throwing on the Temple Mount. It's pretty much an established routine, which occurs on the holidays when Jews flock to the Western Wall and some seek to walk around on top where the Temples stood, despite our neighbors insisting that there were no Temples.It's a time for Arab youth, and now increasingly Arab women, to demonstrate by stones and yelling, which brings forth the police, barricading of the activists in the al Aqsa Mosque, which is a place for gathering stones as well as prayer and incitement by religious leaders.We're hearing the heads of the Palestine Authority and the Jordanian government, including a statement by the King himself, asserting his role as guardian of Muslim holy places in Jerusalem (something disputed by Palestinians). Both Mahmoud and Abdullah are condemning what they call Israeli provocation, and threaten unspecified serious consequences if the provocations continue.The realities are that neither the Palestine Authority nor the Jordanian monarchy would be likely to have survived, or to continue to survive amidst Muslim chaos without the backing of Israel. However, politics being what they are, Israelis must listen to occasional chastisement from our neighbors, seeing them as coded messages hoping to prevent any further escalation so that we can all live in what approaches peace.Subtleties are everywhere in politics, and here they exist on the borders of what may develop to be serious warfare. It takes some skill to understand what is being said and done, along with a hope that others are keeping to their side of unwritten agreements that things not go too far.An incident on the Temple Mount in 2000 contributed to the onset of the second intifada, when more than a thousand Israelis and more than four thousand Palestinians died. In such a setting, predictions are especially risky, both in the intellectual sense that they are likely to be wrong, and in the costs of resources and lives if they encourage escalation.