Remove the bad apples
Think of your pension pot like a basket of apples. A few bad ones can spoil the batch.
Companies that have a negative social outcome could be seen as bad apples. Granted they have traditionally made money for investors, but if you had the choice would you support them directly?
If you could custom build your own pension pot from scratch, would you support tobacco companies, weapons manufacturers, or the fossil fuel industry?
This is a fundamental question that ethical or socially responsible investing asks, that traditional strategies did not. Your pension savings are primarily about providing a standard of living in future, but increasingly people are asking about the methods used to achieve this goal.
Removing the bad apples
Each ethical fund will have its own criteria of assessment and they do vary from one fund to another. Many of them largely agree on what removing the "bad apples" entails. If you have a particular desire to exclude a particular industry or company, you can dig deeper to find out what position a fund has taken on that element.
It can be a very personal thing, and there is no one size fits all approach. With a small amount of research and some independent professional help you can find a solution to suit your pension goals that does not conflict with your own personal ethics.