Let us tarry a while over the point which unites the three groups, which is common to the three mechanisms of tongue slips. Fortunately, that is unmistakable. In the first two groups the interfering tendency is recognized by the speaker; in the first there is the additional fact that it showed itself immediately before the slip. In both cases, however, it was suppressed. The speaker had made up his mind not to convert the interfering tendency into speech and then the slip of the tongue occurred; that is to say, the suppressed tendency obtains expression against the speaker's will, in that it changes the expression of the intention which he permits, mixes itself with it or actually puts itself in its place. This is, then, the mechanism of the tongue slip.
From my point of view, I can also best harmonize the processes of the third group with the mechanism here described. I need only assume that these three groups are differentiated by the different degrees of effectiveness attending the suppression of an intention. In the first group, the intention is present and makes itself perceptible before the utterance of the speaker; not until then does it suffer the suppression for which it indemnifies itself in the slip. In the second group the suppression extends farther. The intention is no longer perceptible before the subject speaks. It is remarkable that the interfering intention is in no way deterred by this from taking part in the causation of the slip. Through this fact, however, the explanation of the procedure in the third group is simplified for us. I shall be so bold as to assume that in the error a tendency can manifest itself which has been suppressed for even a longer time, perhaps a very long time, which does not become perceptible and which, therefore, cannot be directly denied by the speaker. But leave the problem of the third group; from the observation of the other cases, you most draw the conclusion that the suppression of the existing intention to say something is the indispensable condition of the occurrence of a slip.
We may now claim that we have made further progress in understanding errors. We know not only that they are psychic acts, in which we can recognize meaning and purpose, and that they arise through the mutual interference of two different intentions, but, in addition, we know that one of these intentions must have undergone a certain suppression in order to be able to manifest itself through interference with the other. The interfering intention must itself first be interfered with before it can become interfering. Naturally, a complete explanation of the phenomena which we call errors is not attained to by this. We immediately see further questions arising, and suspect in general that there will be more occasions for new questions as we progress further. We might, for example, ask why the matter does not proceed much more simply. If there is an existing purpose to suppress a certain tendency instead of giving it expression, then this suppression should be so successful that nothing at all of the latter comes to light; or it could even fail, so that the suppressed tendency attains to full expression. But errors are compromise formations. They mean some success and some failure for each of the two purposes. The endangered intention is neither completely suppressed nor does it, without regard to individual cases, come through wholly intact. We can imagine that special conditions must be existent for the occurrence of such interference or compromise formations, but then we cannot even conjecture what sort they may be. Nor do I believe that we can uncover these unknown circumstances through further penetration into the study of errors. Rather will it be necessary thoroughly to examine other obscure fields of psychic life. Only the analogies which we there encounter can give us the courage to draw those assumptions which are requisite to a more fundamental elucidation of errors. And one thing more. Even working with small signs, as we have constantly been in the habit of doing in this province, brings its dangers with it. There is a mental disease, combined paranoia, in which the utilization of such small signs is practiced without restriction and I naturally would not wish to give it as my opinion that these conclusions, built up on this basis, are correct throughout. We can be protected from such dangers only by the broad basis of our observations, by the repetition of similar impressions from the most varied fields of psychic life.
We will therefore leave the analysis of errors here. But may I remind you of one thing more: keep in mind, as a prototype, the manner in which we have treated these phenomena. You can see from these examples what the purposes of our psychology are. We do not wish merely to describe the phenomena and to classify them, but to comprehend them as signs of a play of forces in the psychic, as expressions of tendencies striving to an end, tendencies which work together or against one another. We seek a dynamic conception of psychic phenomena. The perceived phenomena must, in our conception, give way to those strivings whose existence is only assumed.