High ProbabilityFuture predictions always involve some degree of uncertainty. If you look down at your shoe and it is untied, you may believe with some certainty that you will be able to reach down and tie it. However, some rare event might disrupt your plans such as an earthquake. As such, when people speak of certain probabilities they usually mean a high probability such as 99.999%.
Almost SurelyIn probability theory, a probability of 100% is referred to as "almost surely." This is a recognition of the fact that things are always at least a little uncertain. For example, if you flip a coin, the result will almost surely be one of the following: heads, tails, a coin that lands on its side.
Almost NeverAlmost never is the opposite of almost surely in probability theory. It refers to a 0% chance of an outcome. For example, in a poker game without wildcards there is almost never a five of a kind hand.
Objective TruthAn objective truth is something that is almost surely true based on rigorous and objective evidence. For example, it is an objective truth that the Earth is roughly spherical, or more accurately the Earth is an oblate spheroid.
Pragmatic TruthPragmatic truth is taking everything you know to be true about something and not going any further. If you know that Germany is a country, then you are certain that Germany is a country and nothing more. You may have heard that it is a big country but you don't consider this true unless you are certain.
Certain BeliefIt is relatively common for an individual to view a belief as certain. This doesn't mean that others can't hold contrary beliefs that they also judge as certain. For example, a father may be certain that his daughter did not cheat on an exam based on faith in her character. The principle of the school may be equally certain in his belief that the daughter did cheat based on trust in the testimony of another student.
InfallibilityInfallibility is the belief that something or someone can't be wrong. For example, an art student who believes that a particular artwork is certainly priceless because it is acclaimed by a respected institution.
NotesThe exact nature of certainty is an active area of philosophical debate. For example, it could be argued, from a purely logical point of view, that certainty requires infinite precision such that it isn't technically possible to be certain of anything.
A class of knowledge and prediction that have no chance of error.