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Richard A. Gabriel [...] argues that, while Alexander was clearly a successful soldier-adventurer, the evidence of real greatness is simply not there. The author presents Alexander as a misfit within his own warrior society, attempting to overcompensate. Thoroughly insecure and unstable, he was given to episodes of uncontrollable rage and committed brutal atrocities that would today have him vilified as a monstrous psychopath. The author believes some of his worst excesses may have been due to what we now call Post Traumatic Stress Disorder, of which he displays many of the classic symptoms, brought on by extended exposure to violence and danger. Above all the author thinks that Alexander's military ability has been flattered by history. Alexander was tactically competent but contributed nothing truly original, while his strategy was often flawed and distorted by his obsession with personal glory. This radical reappraisal is certain to provoke debate.
Well, if your only intention is to provoke debate, I don't think you'll be a very respected scholar.

Alexander III was indeed a bit of a misfit, to use Gabriel's terminology, but it predominantly worked to his benefit. His eccentricities were generally things like his kind treatment of women in his capture, his close relationship with his soldiers even at the height of his power (something unusual amongst his contemporaries), his love of literature (such as the oft-repeated anecdote that he slept with his annotated copy of the Iliad beneath his pillow), and his predilection towards men (he had only three wives, a low number compared to his father etc., all married for political reasons rather than outright attraction, and spent most of his time away from them, only producing one heir before his death).

The statement "he was given to episodes of uncontrollable rage and committed brutal atrocities that would today have him vilified as a monstrous psychopath" is certainly a ridiculous one, given that Alexander did not exist today, so it is ultimately pointless to suppose how he would have been armchair-diagnosed in the modern day. He lived in a very different time, and as tempting as it can be to judge him by modern standards, that is something that should be left to laypersons, not academics who by all means ought to have an understanding of the dangers of presentism. He was certainly "vilified as a monstrous psychopath" in his own time, most notably by his enemies. The diagnosis of PTSD, while not unreasonable, is also pointless: PTSD does not turn people into "monstrous psychopaths," nor are "monstrous psychopaths" merely misunderstood victims of PTSD. Some of his "worst offences" include his attack upon the city of Tyre, through which he transformed the island into a peninsula and slaughtered the vast majority of the city's male occupants (some 8 thousand according to Arrian) and sold the women and children into slavery without exception (some 30 thousand by the same source). Claiming this was caused by PTSD rather than the perhaps less charitable but more historically supported explanation—Alexander was angered that he hadn't been able to take the city, and exacted his revenge on its population—paints an unpleasant portrait not only of Alexander's actions but also of everyone suffering from PTSD, most of whom have never done something analogous to Alexander's treatment of Tyre.
[...] Alexander's military ability has been flattered by history.
Fair enough, perhaps.
Alexander was tactically competent but contributed nothing truly original,
This is demonstrably false. Regardless of how you feel about him, the fact remains that he conquered the largest empire of his time, and remained undefeated in battle. I would argue that at least the former counts as "truly original."
while his strategy was often flawed and distorted by his obsession with personal glory.
This is reasonable enough, although it's difficult to ascertain how flawed his strategy was because, as I mentioned, he was undefeated in battle. (Of course, he fought for under 20 years, from his appointment as his father's general at the age of 16 to his death at the age of 32, so it's impossible to tell if he would have been less prone to victories had he lived longer.)

Listen. There is a lot to criticise about Alexander III, and I myself have done the majority of it. By modern standards, yes, he would be considered a genocidal lunatic, but he did not exist in the realm of modern standards; by his contemporary standards, the ones which actually matter, he was a brilliant military general and respected ruler. He earned the appellation "the Great" (Ἀλέξανδρος ὁ Μέγας) in his own time; it was not bestowed upon him in modernity.