At the presidential debate, Trump argues that his administration effectively tackled drug addiction and kept numbers low until the COVID-19 pandemic and Biden's presidency, which he claims led to a massive increase in drug trafficking due to Biden's alleged weakness on border security and his reversal of Trump's policies. While Trump correctly points out the severity of the drug crisis and the importance of border security in addressing it, he relies on some questionable causal reasoning, and fails to provide a clear, substantive plan to help Americans currently struggling with addiction.

1. red herring with ad hominem • This statement diverts from the original question about the opioid crisis and addiction treatment by shifting the topic to the U.S. deficit and trade with China.

...we now have the largest deficit in the history of our country under this guy, we have the largest deficit with China.... ​He gets paid by China. He's a Manchurian Candidate. He gets money from China. So I think he's afraid to deal with him or something.

As part of the red herring, Trump labels Biden a "Manchurian Candidate" (a covert Chinese operative) and claims he is paid by China, aiming to discredit him without engaging in substantive debate.

2. post hoc ergo propter hoc • Trump suggests Biden's presidency is the direct cause of increased drug trafficking and overdose numbers without proving a causal relationship.

...we were getting very low numbers. Very, very low numbers.

Then he came along. The numbers - have you seen the numbers now? ...the number of drugs coming across our border now is the largest we've ever had by far.

This appears to be the "post hoc ergo propter hoc" (after this, therefore because of this) fallacy. This fallacy occurs when someone concludes that because event Y followed event X, event Y must have been caused by event X, without sufficient evidence to support the causal link.

In this case, Trump is suggesting that the increase in drug numbers crossing the border is a direct result of Biden's presidency ("Then he came along. The numbers - have you seen the numbers now?"). He implies that the low numbers during his own presidency were due to his policies and that the high numbers under Biden are a consequence of Biden's actions.

However, Trump does not provide any concrete evidence to support this causal link. There could be various factors contributing to the change in drug trafficking numbers, such as changes in drug production in other countries, shifts in demand, or evolving tactics by drug cartels. Simply pointing to a temporal sequence (low numbers under Trump, high numbers under Biden) does not prove that Biden's presidency is the cause of the increase.