Mutation In Evolution

I had always thought mutations could be a result of other factors rather than just an accident. My interest in this subject is as a layman. 

Most articles I read seemed to indicate that mutations were completely by chance. I seem to remember this from a book I read earlier "Mutations happen by accident. The subsequent natural selection does not." 

Now here are some quotes:

"It is important to realize that mutations do not occur in response to the environment. They simply happen." 
From http://www.talkorigins.org/faqs/mutations.html

"The emerging molecular mechanisms of stress-induced mutagenesis vary but share telling common components that underscore two common themes. The first is the regulation of mutagenesis in time by cellular stress responses, which promote random mutations specifically when cells are poorly adapted to their environments, i.e., when they are stressed." From
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3319127/

"The effect of radiation on the mutation rate in flies had two implications...Muller's experiments demonstrated that heredity could be manipulated quite easily" 

While Siddhartha Mukherjee's book "The Gene" page 119, talks about how a specific intensity of X Ray introduced mutations in flies. In this example, I wondered, playing the devil's advocate, whether it's not possible that the mutations were still an accident but  that natural selection resulted in the survival of the mutated flies. In the absence of the Xray, there was no such mutation. Hence Xray did cause the mutation.
Is this experiment, conducted around 1930, not proof that mutation can be designed to happen, rather that environment plays a part in mutation?

https://www.seedquest.com/keyword/seedbiotechnologies/primers/varietydevelopment/inducedmutation.htm - This link also talks about how mutation can be induced.

Specific mutations that have been consistently reproduced in organisms under controlled conditions, as in a lab, prove that mutations are not just an accident.

It is possible that several kinds of mutation can happen in an experiment of which only a few pass the natural selection test. To determine the list of all mutations that happen one has to pause or block natural selection from happening. If natural selection cannot be paused then the entire test shows the result of mutation and of natural selection together. 

Lab experiments show the final result of induced mutation and natural selection acting on top of it. Hence the chronological sequence is: 
Lab condition causes mutations on which natural selection works which results in the survival of some mutants and perhaps destruction of other mutants.

In this context, I have quotes from a nice book "Primate Change" by

In "Primate Change" book by Cregan-Reid

• "In most other primates, the foot has a different set of functions and consequently a different design."

My comment:The "design" in evolution doesn't work backwards from a purpose unlike engineering design. Mutation causes a different design and it's my belief that the animal learns to use the new design as best as it can. Design (of our body) doesn't have purpose in mind. Hence I am uncomfortable with the word "consequently" in the quote. When I contacted the author about this, he replied that he meant "Design" to imply something like Shape and not Intention / Purpose.

• "As the guts in these hominins shrank (suggesting an improvement in the quality of their food), it meant that other organs could receive more evolutionary attention in future generations."

My comment:Is the total Evolutionary Attention a constant? Again, are we supposing a design in Evolution, a prioritization and planning?

Interesting articles on the subject of whether evolution is predictable:

• https://www.scientificamerican.com/article/predictable-evolution-trumps-randomness-of-mutations/
• http://science.sciencemag.org/content/323/5915/746
• https://www.mpg.de/10636321/is-evolution-predictable

Additional Reading

https://vbala99.blogspot.com/2019/01/extinction-and-allele.html