So does this mean that psychology determines history? No, not at all. The “psychological interpretation” of history, Peikoff insists, is a plausible but mistaken theory. What is wrong with it? Let us examine the reasons Peikoff gives for rejecting the psychological interpretation:
The first thing to ask is: what is the source of psychological factors? Where do they come from? What is their cause? … Let me give you the answer… All the psychological factors … reduce to one element, however complex the terminology. They reduce to emotions… And the source of emotions is: ideas…
This is the basic answer to the psychological interpretation of history. That theory comes down to the view that emotions are the key factor in history. But emotions on a scale that shapes a culture are a consequence of philosophy.
In other words, the Objectivist philosophy of history is the application of Rand’s theory of emotions to history. If Rand’s theory of emotions is wrong, then her theory of history must be wrong as well. So this leads to the obvious question: Is Rand’s theory of emotions right? Well, it just so happens that ARCHNBlog has already answered this question. That post concluded as follows:
[The Objectivist] view of emotions … has been refuted by research done in cognitive science, neuroscience, and evolutionary psychology. These sciences have discovered that animals (including human beings) have "primary emotions," which are "innate" and "preorganized" and which depend on limbic system circuitry in the brain. They have discovered that emotions are critical in thinking, so that the notion that "man can live exclusively by reason," when accompanied by the additional notion that "emotions are not tools of cognition," misrepresents what actually happens in cognition. Human beings are not blank slates. Their emotions are not programmed into their “subconscious” by their conscious minds. That view is no more credible than would be an astrological view of emotions. On naturalistic assumptions, emotions are and must be the product of evolution. They are tools of survival, forged in the evolutionary furnace.