Popular conservative commentator Michael Knowles says the Supreme Court upholding President Donald Trump‘s ban on transgender people serving in the military is a smart move … ’cause he thinks it’s a serious disease that affects their combat readiness.

We spoke with Knowles — a longtime podcast host at Ben Shapiro‘s Daily Wire — came by “TMZ Live” Wednesday to discuss the court’s ruling this week … explaining he’s all for it because mental health issues in the trans community prevent them from being effective soldiers.

Knowles references studies showing higher rates of chronic disease among members of the trans community … and adds Americans voted for Trump fully knowing this was something he was going to do, thereby cosigning it.

Our own Harvey Levin pushes back … asking what it has to do with their ability to fire a weapon — and, Michael says they’re much less physically fit, even former Olympic athlete Caitlyn Jenner.

As for whether this ruling means all gay people might be banned from the military in the future … Michael says there’s no way — ’cause many gay individuals have already served in the military for decades.

However, he’s also standing by “Don’t Ask, Don’t Tell” here … arguing it’s effective, while Harvey fires back.

Knowles repeatedly calls being transgender a “serious mental illness” … it’s worth noting that gender dysphoria — which, according to the American Psychiatric Association, is “psychological distress that results from an incongruence between one’s sex assigned at birth and one’s gender identity” — is included in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

However, gender non-conformity is not listed in the manual … and, the authors went out of their way to state, “gender non-conformity is not in itself a mental disorder.” All of this is in an attempt to diagnose a real issue instead of pathologizing identity.

Michael, Harvey and Charles also get into an interesting conversation about what perception really means … watch the clip all the way through to hear it.

There’s a ton of debate around trans issues everywhere — from bathrooms, to youth sports, and now the military … and, we’re sure it will continue for years to come.