of actually specifying these properties. In fact, this is the form in which, for example, Carnap used explicitly to put the question of protocol statements, while later declaring it to be a question which is to be settled by an arbitrary decision. 

On the other hand, we find many expositions which seem to presuppose that by "protocol statements" only those assertions are to be understood that also temporally precede the other assertions of science. And is this not correct? One must bear in mind that it is a matter of the ultimate basis of knowledge of reality, and that it is not sufficient for this to treat statements as, so to speak, "ideal constructions" (as one used to say in Platonic fashion), but rather that one must concern oneself with real occurrences, with events that take place in time, in which the making of judgments consists, hence with psychic acts of "thought," or physical acts of "speaking" or "writing." Since psychic acts of judgment seem suitable for establishing inter-subjectively valid knowledge only when translated into verbal or written expressions (that is, into a physical system of symbols) "protocol statements" come to be regarded as certain spoken, written or printed sentences, i.e., certain symbol?complexes of sounds or printer's ink, which when translated from the common abbreviations into full-fledged speech, would mean something like: "Mr. N. N. at such and such a time observed so and so at such and such a place." (This view was adopted particularly by O. Neurath). As a matter of fact, when we retrace the path by which we actually arrive at all our knowledge, we doubtless always come up against this same source: printed sentences in books, words out of the mouth of a teacher, our own observations (in the latter case we are ourselves N. N.). 

On this view protocol statements would be real happenings in the world and would temporally precede the other real processes in which the "construction of science," or indeed the production of an individual's knowledge consists. 

I do not know to what extent the distinction made here between the logical and temporal priority of protocol statements corresponds to differences in the views actually held by certain authors -- but that is not important. For we are not concerned to determine who expressed the correct view, but what the correct view is. And for this our distinction between the two points of view will serve well enough. 

As a matter of fact, these two views are compatible