Much of modern medicine involves covering up symptoms with drugs proven to do this, without understanding the underlying cause of the symptom.
What, really? There certainly is a lot of that approach around, but it's not what I think of when I think of modern medicine, as opposed to more traditional forms. Can you give examples?
Most of the ones I can think of are things that have fallen to the modern turn to evidence-based practice. The poster-child one in my head is the story of H. pylori and how a better understanding of the causes of gastritis and gastric ulcers has led to better treatments than the old symptom-relieving approaches. (And I'll tell you what, although Zantac/Ranitidine is only a symptomatic reliever, it was designed to do that job based on a thorough understanding of how that symptom comes about, and it's bloody good at it, as anyone who's had it for bad heartburn or reflux can attest.)
When I think of modern medicine, I think of things like Rituximab, which is a monoclonal antibody designed with a very sophisticated understanding of how the body's immune system works - it targets B cells specifically, and has revolutionised drug treatment for diseases like non-Hodgkin's lymphomas where you want to get rid of B cells. So much so that for some of those lymphomas, we don't have very robust 5 year survival data, because the improvement over traditional chemotherapy alone is so large that the old survival data is no use (we know people will live much longer than that), and Rituximab hasn't been widely used for long enough to get new data. In the last 25 years our understanding of cancer has gone from "it's mutations in the genes, probably these ones" to vast databases of which specific mutations at which specific locations on which specific genes are associated with which specific cancer symptoms, and how those are correlated with prognosis and treatment. And as a result cancer survival rates have improved markedly. We don't have "A Cure For Cancer", and we now know we never will, any more than we can have "A Cure For Infection", but we do have a good enough understanding of how it happens to get much better at reducing its impact.
Even modern medical disasters like Vioxx are hardly a result of a lack of understanding the underlying cause, but more us learning more about other complexities of human biology. Admittedly we don't yet fully understand how pain works, but we do know enough to know that targeting COX-2 exclusively (rather than COX-1 as well, which looks after your gut lining) would be safer for your gut. This is understanding down at the molecular level. It turns out in large scale studies that they are safer for your gut, but of course they're not very safe for your heart, so we've stopped using them. And actually doing the full-scale research on modern rationally-designed drugs like Vioxx suggests that similar old drugs (that we never bothered to test) have the same effect on hearts.
You're right, we do understand the pathophysiology of many diseases, and those are the ones that have been mostly eradicated. The major chronic diseases that remain are very poorly understood such as type II diabetes, cancer, cardiovascular disease, and alzheimer's.
I spend a lot of time reading about 'alternative' ideas about these diseases, and many seem promising, but aren't taken seriously by the mainstream. It's definitely possible that they're ignored for a good reason, but I haven't been able to find the reasons yet. This is the biggest problem I've ...
Suppose you distrusted everything you had ever read about science. How much of modern scientific knowledge could you verify for yourself, using only your own senses and the sort of equipment you could easily obtain? How about if you accept third-party evidence when many thousands of people can easily check the facts?
My purpose with the question isn't to cast radical doubt on science; rather, it's an entertaining game of trying to understand how we know what we know. Thinking through these sorts of questions also helped me notice interesting things in the history of science that I hadn't previously focused on. It might also be of interest from a science education perspective.
Some things are much easier to check than they used to be. As late as the 19th century, there were people who were publicly skeptical about the curvature of the earth. Skeptics and scientists did careful measurements (notably the Bedford Level Experiment) to observe the earth's curvature. Today, you can verify it by phoning a friend a few time zones away and noticing that the sun reaches the zenith at steadily later times as you move west. This only makes sense if the earth is curved.
Some things are still hard to check. I don't know an easy way to show that the Earth orbits the Sun. The direct way to show it would be to measure stellar parallax. But even the closest stars have a parallax of less than an arcsecond. My understanding is that very few amateurs are able to take measurements with that level of precision.
Some things are surprisingly easy. There are lots of easily accessible demonstrations of quantum phenomena. For example, a ten dollar spectroscope will show you that an incandescent light bulb has a continuous spectrum, and that LEDs and fluorescent bulbs don't. Bright-line spectra are very much a quantum mechanical phenomenon -- it's a sign that the atoms in the light source have fixed energy transition levels. Spectroscopy was one of the key early lines of evidence for quantum mechanics, and it blows my mind that it's something you can just see whenever you want, with a negligible equipment cost.
Pretty much all of modern chemistry and solid state physics rests on a quantum foundation, and you can test a great deal of chemistry pretty easily. If you are in doubt that water is a bonded compound of two gasses, you can do the electrolysis very easily yourself. You can observe the periodicity of chemical elements yourself if you buy alkali metals (don't try this one at home!). If you are willing to accept slightly indirect evidence, the entire semiconductor industry is about precisely controlling the conductivity of impure silicon, and this would make no sense if quantum mechanics weren't a reliable guide to electron energy levels in the solid state.
I don't feel quite as qualified to play this game for biology. I imagine that antibiotic resistance is a well-enough documented case of evolution through natural selection to serve at least as a proof of concept. DNA sequence comparisons across species are emphatic evidence of taxonomic trees, if you trust the scientists not to be part of a vast conspiracy.
It feels almost impossible that it's easier to see quantum mechanical effects than it is to see that the earth orbits the sun, but it does seem that way.
Some questions: