  Rather than holding that probability is a measure of degree of confidence or belief, then, Peirce adopted an objectivist notion of probability that he explicitly likened to the doctrine of John Venn. Indeed, he even held that probability is actually a notion with clear empirical content and that there are clear empirical procedures for ascertaining that content.  First, he held, that that to which a probability is assigned, insofar as the notion of probability is used scientifically, is not a proposition or an event or a state; nor is it a type of event or state.  Rather, what is assigned a probability is an argument, an argument having premisses (Peirce insisted on this spelling rather than the spelling “premises.”) and a conclusion. Peirce’s view in this regard is virtually indistinguishable from the view of Kolmogoroff that all probabilities are conditional probabilities. Second, Peirce held that, in order to ascertain the probability of a particular argument, the observer notes all occasions on which all of its premisses are true, case by case, just as they come under observation. For each of these occasions the observer notes whether the conclusion is true or not. The observer keeps a running tally, the ongoing ratio whose numerator is the number of occasions so far observed on which the conclusion as well as the premisses are true and whose denominator is the number of occasions so far observed on which the premisses are true irrespective of whether or not the conclusion is also true. At each observation the observer computes this ratio, which obviously encompasses all the observer’s past observations of occasions on which the premisses are true. The probability of the argument in question is defined by Peirce to be the limit of the crucial ratio as the number of observations tends to grow infinitely large (if this limit exists).