Mrthdrb

This is why. Last time there were border posts, the IRA blew them up.

Today (10 April 2019) is the 21st anniversary of the Good Friday Agreement.

This is more of an addition to phoog's answer, but I think it's an important enough point to emphasize separately, as it seems a common source of confusion. Phoog said:

The question of immigration controls between the UK and other EU countries is entirely independent of the UK's membership in the EU.

The keyword here is "controls". Because stopping legal immigration from the EU is one of the main reasons people voted Brexit. In other words, the worry was not mainly about illegal immigration sneaking in as much the legal one that gets (legally) through the existing controls at UK's borders. So "taking back control" of the border in the UK Brexit debate does not have the same meaning as in the US debate on the illegal immigration through/from Mexico.

Granted, during the Brexit referendum, the specter of Syrian refugees was raised. But these would have also been probably legal as asylum seekers unless (or rather until) rejected as such, which in the case of Syrians was unlikely given the civil war.

in the hypothesis of a hard Brexit, isn't a soft Irish border a potential backdoor for illegal immigration to the UK?

Yes. And if anything, this might prompt the UK to set up some hard borders on its side of the border, much like the EU is discussing border checks on its side for livestock and food, to make sure that no chlorinated chicken from the US or similarly unwanted products (food or otherwise) enter the EU market.

If not what is wrong in the above reasoning?

Ireland, like the UK, isn't part of the Schengen zone.

Also, there technically are border controls (as in passport checks) today at ports (air and sea) between Great Britain (as in the island) and Ireland (as in the island), and between the British Isles (as in the UK and Ireland) and the Schengen zone.

Assuming that this reasoning is correct, why influential hard-Brexiteers don't campaign for a hard Irish border in order to actually control immigration?

Because Brexit itself is a hard enough sell as things are. Putting up a hard border forward to boot means throwing the Good Friday agreement -- a peace deal -- out the window. It's not a good idea to be campaigning on that.

this answer claims that (some?) hard-Brexiteers hope that Ireland would follow the UK and leave the EU as well, and that would solve the problem. This options seems very unlikely given that Ireland's economy relies on being part of the EU (let alone the growing anglophobia in Ireland), but is there any evidence to back this claim?

No, except perhaps in ERG and DUP wet dreams.

The hard Brexiteers don't really care about immigration. Immigration was just a tool they used to get what they really want: economic freedom to exploit the UK. Things like employment rights and financial regulations that derive from the EU limit get in the way of them making money.

The immigration angle was just something they used to get enough people to vote for brexit. Now it's a useful excuse for not honouring the pre-referendum proposals to stay in the Single Market and Customs Union.

Brexiteers require a deal to be formulated that will gain enough support placating the DUP is an important part of this as they are unlikely to receive much support form Labour or the remain supporters in parliament needed to get a majority. It's worth remembering the hard brexiteers primarily want brexit they are simply OK or happy with the UK leaving on harsher terms as long as brexit is delivered.

The issue of the Irish border is perhaps one of the most important issues for any brexit deal as it it isn't a question about some benefit that might be received at some point in the future but something that handled poorly could lead to civil disturbances in Ireland that might even result in incidents in other areas of the UK and potentially island ceding from the UK, this would be a major issue for the government and the conservative party (if they were seen as responsible)

The issues with the Irish border are also a concern for the ROI who would be unlikely to agree to a deal with the UK that doesn't resolve the border concerns in a way that would allow some movement between ROI and Northern Island.

As well as the option of having a soft border into the UK through Northern Ireland there are a number of other options such as having some form of a border in the Irish sea between the Northern Island the rest of the UK. Which can be resolved at some later point (after all brexit is a long game that no-one really expects to benefit from any time soon) and this can be changed later when the support of the DUP is not so important and as an internal matter that doesn't require the EU to be involved . Equally a soft border is an issue for the EU as well and thus brexiteers would take make the argument that as a matter of mutual concern than some kind of resolution would be possible.

First question: in the hypothesis of a hard Brexit, isn't a soft Irish border a potential backdoor for illegal immigration to the UK? If not what is wrong in the above reasoning?

As you say a hard border is a concert for immigration but there options available down the line that might help reduce the impact of such a border on the rest of the UK.

Second question: assuming that this reasoning is correct, why influential hard-Brexiteers don't campaign for a hard Irish border in order to actually control immigration?

Brexiteers are more concerned with achieving brexit than this specific issue especially as there are options that could protect the rest of the UK from the immigration whilst still avoiding civil unrest. They also require support form the DUP for whatever deal can be made.

for hard Brexiteers, taking back control of the UK borders to limit immigration is a major outcome of Brexit

For some of them, maybe. But certainly not all; many of them are globalist libertarians with no desire whatsoever to reduce immigration.

A few points:

• 
  "Global Britain" and "go global" were key Leave slogans.


• Only one-third of Leave voters cited immigration as their main motive in Lord Ashcroft's exit poll.


• Many key Leave supporters are pro-immigration:
  
  
  • cabinet member and one-time PM contender Michael Gove speaks approvingly of Britain's "liberal approach" to immigration
  
  
  • other previous PM candidate Boris Johnson has called for an "open approach", "clashed" with Remainer Theresa May due to his defence of immigrant rights, and called on the government to make a "liberal" case for immigration.
  
  
  • yet another PM contender, Daniel Hannan, the Secretary-General of the biggest EU-skeptical EU conservative party, is a pro-immigration liberal who has written multiple articles denouncing Remainer claims that Brexit was motivated by a desire to restrict immigration. (One example.)
  
  

The narrative that the Brexit vote was motivated by a desire to reduce immigration is common on the pro-Remain Left, but for actual pro-Leave politicians it's often either a secondary objective or something they actively oppose. There's no need to explain why these people are taking positions that go against their values, because they don't go against their values in the first place.

First question: in the hypothesis of a hard Brexit, isn't a soft Irish
border a potential backdoor for illegal immigration to the UK? If not
what is wrong in the above reasoning?

Second question: assuming that this reasoning is correct, why
influential hard-Brexiteers don't campaign for a hard Irish border in
order to actually control immigration?

When you stop all traffic at a hard border to check for papers, you slow down commerce. In the age of just-in-time delivery to factories, hour-long waiting periods on the border hurt the economy. The Irish and Northern-Irish had an open border for over 20 years, and they pretty much like that open border.

So, apart from issues regarding terror, the Troubles and the Good Friday Agreement, a hard Irish-Northern Ireland border would hurt the economy.

My guess is, if you find some hard-Brexiteer who makes the case for a hard border in order to tackle immigration, it's unlikely that this one would be from Northern Ireland.

If the UK, at some point in time, finds that the soft border with Ireland creates an immigration loophole, they can always create checks for the connections between the islands of Ireland and Britain, i.e. check everthing that crosses the Irish Channel (flights and ferries). Right now, this is considered as breaking up the UK by many Brexiteers, thus such an additional channel border likely won't make it into any official Brexit plans. Yet, politicians can be quite pragmatic.

in the hypothesis of a hard Brexit, isn't a soft Irish border a
potential backdoor for illegal immigration to the UK?

Technically yes, but in reality no. Remember that the UK and the Republic of Ireland will remain in the same immigration zone after Brexit (Common Travel Area, or CTA). In the case of illegal immigration, that immigration will remain illegal after a Hard Brexit. The vast majority of illegal immigration is made up of people trying to cross the channel illegally, either by sneaking into vehicles that are crossing the channel legally, or (more recently) by using dinghies and hoping for the best. Leaving the EU won't change geography, it won't change the CTA, it won't change the fact that vehicles will legally cross the channel, and crucially it doesn't change the desperation of those who are trying to cross. Because the UK already has an opt out I don't see how leaving the EU will increase the thoroughness of the checks performed on incoming lorries*, it is a question of time/space/resources that determines how many vehicles are checked.

Therefore those who seek to enter the UK illegally after a Hard Brexit will still choose to cross from Calais to Dover/Folkestone rather than by first of all going on a much longer ferry crossing to the Republic of Ireland and then exploiting the soft border. It's the fact that the Republic of Ireland is still in the CTA and geography that makes the difference.

Second question: assuming that this reasoning is correct, why don't influential hard Brexiteers campaign for a hard Irish border in order to actually control immigration?

Because they know that a hard border will kill the Northern Irish economy, which in turn will affect the votes for the DUP (and their supporters in the ERG). In a worst-case scenario the economic impact could even make a Border Poll** inevitable, followed by Northern Ireland rejoining the EU by becoming part of the Republic of Ireland. While this would solve the problem of the Irish Border and the Backstop, etc, it is an anathema for many of those who support a Hard Brexit because they are also staunch unionists.

*It may even decrease it. If all vehicles have to be checked due to WTO obligations, they will have less time to check any particular vehicle.

**A Border Poll is the specific name given to a referendum on the future of Northern Ireland within the UK or as a part of the Republic of Ireland. The Good Friday Agreement obliges the UK government to hold a Border Poll in certain circumstances. There is evidence that the Brexit 'journey' has increased support for a Border Poll.

Hard Brexiteers' supporters aren't as concerned with migration from Ireland as they are with (illegal) migration from mainland Europe (and in turn from the Middle East).

Second question: assuming that this reasoning is correct, why don't influential hard Brexiteers campaign for a hard Irish border in order to actually control immigration?

Because the Brexiteers aren't particularly afraid of Irish people. Most other answers correctly point out technicalities regarding the border and immigration is mentioned by almost all of them. What they have not yet pointed out is what immigration they are afraid of / worried about.

Indeed, if we look at research, we find the following, from the abstract of a paper titled Is racial prejudice declining in Britain?:

Little evidence is found for the third hypothesis: British reactions towards black and Asian minorities are broadly similar suggesting racial differences may still be the main factor prompting white hostility to British minorities.

Now, as you might guess, Ireland isn't associated with non-white races at all. France on the other hand, is. For this I will provide two pieces of evidence: firstly Nigel Farage's image on a truck associating nonwhite refugees with the EU in his Brexit campaign (first picture) and secondly the Calais jungle (second picture, showing how it's been reported). Indeed, British seem to be more concerned about the Calais jungle than the French (even though Calais is in France), please consider the third picture showing the result from a YouGov poll.

_{(Image: Philip Toscano/PA)}

_{(Image: northumbrianreflections)}