An interesting problem for a scientist is how to discover something? The mediocre, of course, never even try to solve this while it is probably only a small percentage that gets there. Basically, it is done by observing clues then using logic to interpret them. The method is called induction, and it can lead to erroneous conclusions. Aristotle worked put how to do it, and then dropped the ball at least twice in his two biggest blunders when he forgot to follow his own advice. (In fairness, he probably made his blunders before he worked put his methodology, and lost interest in correcting them. The Physica was one of his earliest works.)
The clues come from nature, and picking them up relies on keeping eyes open and more importantly, the mind open. The first step is to seek patterns in what you observe, and try to correlate your observations. The key here is Aristotle’s comment that the whole is more than the sum of the parts. That looks like New Age nonsense, but look at it from the mathematics of set theory. A set is simply a collection of data, usually expressed as numbers, but not anything should go into it. As an example, I could list all green things I can see, but that would be pointless. I could list all plants, and now I am making progress into botany. The point is, the set comprises all the elements inside it, together with the rule that conveys set membership. It is the rule that we seek if we wish to make a discovery and in effect we have to guess it by examining the data. This process is called induction, and if we get some true statements, we can move on to deduction.
There are, of course, problems. Thus we could say:
All plants have chlorophyll
Chlorophyll is green
Therefore all plants are green.
That is untrue. The chlorophyll will be green, but the plant may have additional dyes/pigments. An obvious case is red seaweed. The problem here is the lazy “therefore”. Usually it is somewhat more difficult, especially in medicine.
Which, naturally in these times, it brings me to COVID-19. What we find is very young people, especially girls, are more or less untroubled. The old have a lot more trouble, and, it turns out more so old men. Now part of the trouble will be that the old have weaker immune systems, and often other weaknesses in their bodies. Unlike wine, age does not improve the body. That is probably a confusing observation, because it leads nowhere and is somewhat obvious.
Anyway, we have a new observation: if we restrict ourselves to severe cases in hospitals, there is a serious excess of bald men. Now, a correlation is not causative, and trying to work out the cause can be fraught with difficulty. In this case, we can immediately dismiss the idea that hair has anything to do with it. However, baldness is also correlated with higher levels of androgens, which are male sex hormones. It was also found that the severe cases in males also usually had high levels of androgens. By itself, we can show this is not a cause either.
So, this leads to a deeper investigation, and it is found that the virus uses an enzyme called TMPRSS2 to cleave the Sars-Cov-2 spike protein, and this permits the cleaved spike to attack the ACE2 receptors on the patient’s cells, and thus permit the viral RNA to enter the cell and begin replicating. What the androgens do is to activate a gene in the virus that expresses TMPRSS2, so what the androgens do is to increase the amount of enzyme necessary to attack a cell. This suggests as a treatment something that will inhibit the viral gene so no TMPRSS2 is expressed. We await developments. (Suppressing androgens in men is not a good idea – they start to grow breasts. However, it also suggests that ACE inhibitors, used to reduce hypertension, might offer some assistance.) Now, the value of a theory can be shown by whether it helps explains something else. In this case, it argues that since pre-puberty children should be more resistant, and girls keep this benefit longer. That is found. It does not prove we are correct, but it is comforting. That is an example of induced science. Induction does not necessarily produce the truth, and conclusions can be wrong. We find out by pursuing the consequences, and either finding we have discovered something, or go back to the drawing board.