I understand that Syme was vaporised because he overthought the concept of the newspeak, but would he have regretted being an avid follower of Big Brother and destroyer of language?
Was Syme really such an avid follower?
I'm going to challenge the premise of your question here, because my interpretation of the character is different. We know that (according to Winston's assessment) Syme will ultimately be considered a threat by the Party because he's too intelligent, but why would that be a threat if said intelligence really is directed 100% in the interests of the Party? If harnessed properly, intelligence is an asset - indeed, a vital asset - to anyone who seeks power and control. Presumably the Thought Police have intelligence (in more ways than one); so does Big Brother himself, if he exists, and many of the Inner Party.
There was something subtly wrong with Syme. There was something that he lacked: discretion, aloofness, a sort of saving stupidity. [...] Syme would be vaporized. Winston would be vaporized. O’Brien would be vaporized. Parsons, on the other hand, would never be vaporized. The eyeless creature with the quacking voice would never be vaporized. The little beetle-like men who scuttle so nimbly through the labyrinthine corridors of Ministries they, too, would never be vaporized.
-- this and all quotes below from Part I, Chapter 5
According to Winston (who is, to be sure, not necessarily a reliable narrator), those who show least intelligence are those least likely to be vaporised. It's the dumb, unthinking 'sheeple' who will be allowed to continue their lives, and those who think too much will disappear.
Now let's look at what we see of Syme:
In an intellectual way, Syme was venomously orthodox. He would talk with a disagreeable gloating satisfaction of helicopter raids on enemy villages, and trials and confessions of thought-criminals, the executions in the cellars of the Ministry of Love. Talking to him was largely a matter of getting him away from such subjects and entangling him, if possible, in the technicalities of Newspeak, on which he was authoritative and interesting.
‘It’s a beautiful thing, the destruction of words. [...] Don’t you see the beauty of that, Winston? It was B.B.'s idea originally, of course,’ he added as an afterthought.
It appeared that there had even been demonstrations to thank Big Brother for raising the chocolate ration to twenty grammes a week. And only yesterday, he reflected, it had been announced that the ration was to be REDUCED to twenty grammes a week. Was it possible that they could swallow that, after only twenty-four hours? Yes, they swallowed it. Parsons swallowed it easily, with the stupidity of an animal. The eyeless creature at the other table swallowed it fanatically, passionately, with a furious desire to track down, denounce, and vaporize anyone who should suggest that last week the ration had been thirty grammes. Syme, too — in some more complex way, involving doublethink, Syme swallowed it.
Syme does act as society expects him to, but it could be more dutiful than really natural. His love for Newspeak and the destruction of language is genuine, but it's only "as an afterthought" that he mentions the great and glorious Big Brother as the instigator of this idea. If he were truly natural in his fervent support of the Party, wouldn't he have mentioned B.B. earlier? His gloating about the execution of traitors could also be just a necessity rather than reflecting his real feelings: he knows he's expected to show satisfaction, so he shows it very well. And when he sees blatant lies on the telescreen, he requires doublethink and not just dumb stupidity to swallow them.
Don’t you see that the whole aim of Newspeak is to narrow the range of thought? In the end we shall make thoughtcrime literally impossible, because there will be no words in which to express it.
Chaucer, Shakespeare, Milton, Byron — they’ll exist only in Newspeak versions, not merely changed into something different, but actually changed into something contradictory of what they used to be. Even the literature of the Party will change. Even the slogans will change. How could you have a slogan like “freedom is slavery” when the concept of freedom has been abolished? The whole climate of thought will be different. In fact there will be no thought, as we understand it now. Orthodoxy means not thinking — not needing to think. Orthodoxy is unconsciousness.
DUCKSPEAK, to quack like a duck. It is one of those interesting words that have two contradictory meanings. Applied to an opponent, it is abuse, applied to someone you agree with, it is praise.
Syme sees too lucidly what's going on in society. The danger of intelligence in the lower orders is always that it might be too perceptive of the oppression around them and the true nature of the system. It's acceptable for higher-ups like O'Brien to see the world for what it really is, and to use that knowledge for things like psychological torture. But someone at Syme's level who possesses such clarity of thought, and chatters about it over lunch, is dangerous. If too many people realise the true direction of the world they live in, they might do something to stop it. True power lies not only in strength but also in ignorance. (Indeed, perhaps I've inadvertently stumbled upon the true meaning of the slogan "Ignorance is Strength": the ignorance of the lower orders is the strength of their masters.)
Indeed, the above points are aptly summarised in the paragraphs where Winston decides that Syme will surely be vaporised:
You could not say that he was unorthodox. He believed in the principles of Ingsoc, he venerated Big Brother, he rejoiced over victories, he hated heretics, not merely with sincerity but with a sort of restless zeal, an up-to-dateness of information, which the ordinary Party member did not approach. Yet a faint air of disreputability always clung to him. He said things that would have been better unsaid, he had read too many books, he frequented the Chestnut Tree Cafe, haunt of painters and musicians.
Again: Syme is a zealous member of society, but zeal is easy to portray, easier in fact the more extreme it is. The lady doth protest too much? He's intelligent and educated enough to fake it.
One of these days, thought Winston with sudden deep conviction, Syme will be vaporized. He is too intelligent. He sees too clearly and speaks too plainly. The Party does not like such people. One day he will disappear. It is written in his face.
Again: Syme has too much lucidity of vision, and he's not afraid to say it how it really is. And that's always a problem, when power relies on keeping the lower orders too ignorant to rise up.
So, what might he have been thinking when he was captured?
Now we're delving more into the realms of speculation, since Syme is a minor character and we don't see into his head well enough to really know exactly how he'd react. But it's worth remembering the concept of doublethink, which someone like Syme would surely have mastered. Even if he secretly hated Big Brother and the Party system, that would only be one part of him; in order to be such a rabid follower, he would have had to internalise it at least to some extent. So he could have been feeling any number of things upon his capture, and very possibly (doublethink!) more than one of these:
- pleasure that the Thought Police were working so well in weeding out undesirables;
- surprise that a loyal citizen such as himself would be taken;
- resignation to his imminent torture and death;
- fear of his imminent torture and death;
- annoyance that he hadn't done better at being a good citizen;
What I don't think he would feel is regret about taking part in the destruction of language. This is an activity he seems to love for its own sake, even apart from its role in the society. He can talk avidly about his work with Newspeak, and only mention as an afterthought that it was Big Brother's idea. He seems to take an artistic pride in this job which is separate from his love or hatred of the Party system. There's no need for doublethink there.
It's not entirely certain that Syme was vaporised. We know only that he is no longer around for Winston to talk with.
If Syme were still useful in his work, or in something related, the Party simply could have reassigned him to another bureau and then made it look like he had been removed from all records to which Winston had access. With Syme gone Winston was more dependent on O'Brien for his inquiries about Ingsoc, Newspeak, etc., and it is likely that the thinkpols assigned to monitoring Winston knew this.