On Monday, staff writer Benjamin Weiser told us about a Life magazine interview with Bernard Welch.

Welch is accused of burglarizing hundreds of local homes and killing Dr. Michael Halberstam.

Life quoted Welch as complaining that his pesonal world has been destroyed by his imprisonment. "I had everything going for me," Welch is quoted as saying, "and he had everything going for him. But now he's dead and I'm in prison. They say I destroyed his life, but he's destroyed mine."

I have spent much of the past 24 hours ponder this comment and trying to understand it, but I have had no success.

I cannot comprehend how Welch can compare himself to Halberstam, or his plight to Halberstam's. I do not understand how he can appear to be so lacking in remorse or even in an awareness of his own misconduct.

Welch clearly does not consider himself a bad person. "I wasn't ripping off people," he told the Life interviewer. "I was ripping off insurance companies."

How does one respond to such twisted reasoning? We have just been through 444 days of trying to make sense of Iranian attitudes and thought processes, and this may have given us some measure of capability for understanding people who are on an entirely different wavelength. But Welch's brain operates in a portion of the spectrum that is wholly unknown to me, and I spent much of Monday trying to "get inside his head," as the expression goes these days.

After failing to arrive at anything that even resembled a reasonable explanation, I gave up the project and went back to finishing the morning paper. I knew that staff writer Kerry Dougherty had put in a day as an unidentified substitute teacher, and I was sure she'd file an interesting story about her experience, so I began with her report of what had happened.

I was dismayed to discover that again I was reading about attitudes I didn't understand. In my day, young people knew they were in school to learn. dThey knew why it was important to learn. And they knew that one of the things they were expected to learn was discipline. But the young people Kerry Dougherty tried to teach were like Bernard Welch, on a different wavelength. They were defiant, insolent, undisciplined and lacking in either a sense of purpose or an awareness of the importance of learning to think and assimilate knowledge.

After Kerry's story had marinated in my mind for a while, I found myself wondering: Is there a connection between the incomprehensible attitudes of high school students and the incomprehensible attitude of a grown man who wants sympathy because his victim's death caused trouble for him? I could quickly reject the notion that an unruly juvenile will necessarily become an antisocial adult. But it was not so easy to reject the suspicion that a more subtle link may exist between conduct during formative years and adult life styles.

Perhaps if we really understood juvenile attitudes toward the rules of social conduct that the adult community deems proper, we would have a better chance to understand adult nonconformists, and to deal with them effectively. Up to now we have done little more than make rules, hire policemen to enforce the rules, hire judges to prescribe punishment for those who disobey, and hire jailers (or executioners) to carry out the punishments. We have not been conspicuously successful as reformers. UN UNFINISHED TASK

By the end of this week, January will be finished and so will Scott Chase's campaign to raise money for Children's Hospital.

If you have been newly summoned to Washington to help President Reagan run the country, perhaps you have not learned about our Children's Hospital. For well over a century it has been faithful to its charter to serve children of every race and creed, whether or not their parents can afford to pay the bill. No child is ever turned away for lack of money.

There is only one way that a hospital with a built-in deficit can continue to subsidize health care for poor children, and that is if people like you and me chip in at the end of each year and wipe out its deficit. So before this week is out, won't you please do your part? Make your check to Children's Hospital and mail it to Scott Chase, care of The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Your contribution will be tax deductible. Thank you.