This is particularly difficult for drugs that affect the brain, like MDMA for PTSD in veterans. What do you use as the control group for that, when patients and clinicians can tell that who got the real thing and who did not. I call this the bridge problem. In order to do science, you have to have a control group, but if I built a bridge across a ravine, we don't have to have cars drive off a cliff and fall into the ravine in order to scientifically prove that the bridge works and exists. We engineered a bridge and put it there and obviously if there was no bridge cars would just fall into the ravine so we don't need to test that the bridge exists. We design the bridge, we rate it up to a certain capacity, we don't test it until it fails, we simply prohibit really heavy trucks from driving on smaller bridges that can't take their weight.

We can't do any of that for drugs that affect emotions and consciousness because we're barely in the stone age of our understanding of the brain and the technology we have to affect it.