[Rejecting P1] For psychology's purposes, there are valid measures in place for studying the mind.
[Rejecting P2] Replications don't always work out, but when they don't, it indicates a poor effect of the experiment, which is a valid result.
[Rejecting P3] Psychology is defined by Merriam-Webster as "the science of mind and behavior."
[Rejecting P4] There are many sciences in which the findings are inconclusive. This does not invalidate psychology's status as a science.